- Email: [email protected]
Stability and thermal conductivity of CuO nanowire for catalytic applications
Journal of Environmental Chemical Engineering 7 (2019) 103255
Contents lists available at ScienceDirect
Journal of Environmental Chemical Engineering journal homepage: www.elsevier.com/locate/jece
Stability and thermal conductivity of CuO nanowire for catalytic applications
T
⁎
Noluthando Kanaa,b, K. Kaviyarasua,b, , T. Khamlichea,b, C. Maria Magdalanec,d, M. Maazaa,b a
UNESO-UNISA Africa Chair in Nanosciences/Nanotechnology Laboratories, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria, South Africa b Nanosciences African Network (NANOAFNET), Materials Research Department (MRD), iThemba LABS-National Research Foundation (NRF), P O Box 722, Somerset West, Western Cape Province, South Africa c Department of Chemistry, St. Xavier’s College (Autonomous), Tirunelveli, 627002, India d LIFE, Department of Chemistry, Loyola College (Autonomous), Chennai, 600034, India
A R T I C LE I N FO
A B S T R A C T
Keywords: CuO nanowire Structural parameters Thermal conductivity enhancement Catalytic applications Electron microscopy
Copper oxide (CuO) nanowire is an interesting material because of the versatile application of photocatalytic phase transition were investigated by the presence of Rhodamine-B (RhB) dye under sunlight irradiation. In this view, CuO nanowire is critical to elucidate the growth mechanism of grain morphology which is specifically rise to the driving force accountable for the progression of 2D nanostructures. Among, the role of the ligands, were determined the chemical mechanism of CTAB including decomposition rate, adsorption constancy and nuclei formation etc. We have confirmed the non-linear trends of the thermal conductivity were enhanced between 25 to 45 °C, which attributes the various factors of the size and shape of the nanoparticles. On the other hand, the Raman studies were exhibited the strong peaks at 246 cm−1, 307 cm−1 and 596 cm−1 where the points at 1517 cm−1 and 1565 cm−1 are signifies to assign the monoclinic orientation of Eg and A1g modes vibration. The photocatalyst were distinguished from the solution mixture by centrifugation to identify its stability and reusability nature at the end of the photocatalytic process. At each end of every cycle, the catalyst was removed from the solution mixture by simple filtration, washed thoroughly with pure ethanol and dried at 120 °C the dried sample used for new cycles. Thus, the driving trials suggest that the practically applicable to explore the nanostructures system for environmental applications such as active sludge, waste water remediation.
1. Introduction We account here on the primary focus of the growth morphology of high-yield, vertical CuO nanowires were produced by hydrothermal technique and the length of the CuO nanowires could be changed from several to tens of nanometres by regulating the oxidation temperature and time respectively [1]. In this view, fully-fledged CuO nanowires were persevering to be single-crystalline with different axial crystallographic orientations [2]. Remarkably, we have been efforts to synthesize CuO nanowire with considerable success, but we are largely limited to morphological structures ranges from 10 to 5 nm size compared to great deal with biological molecules for example enzymes, receptors among others and so on [3]. In addition, due to the structural stability of Cu ions which can be interact with bioluminescence molecules and it has suitable in diagnosis for cancer treatment [4,5]. Depending on the medical condition, of these CuO nanowire are very firm and their activity is extensively when linked with an α-endosulfan ⁎
molecules, it seems like, CuO nanowires were grown different directions, however copper ions accumulating together to solve the difficulties of poor ionic conduction and the deficient volume retention which existing in nanoparticles not like bulk counterpart [6]. Moreover, Synthesis of CuO nanowires is very less expensive when compared to gold and silver nanoparticles whish possess excellent antimicrobial agent because of their unusual crystal orientation, but now-a-days recent researchers have focused on green routes for the synthesis and production of nanoparticles extensively [7]. Green synthesis is one of the simplest and easiest methods for synthesis of these nanoparticles are very stable, and their activity is longer when compared with organic anti-microbial agents also [25]. The advantage of producing like these CuO nanowires it is easy, fast, cost effective and flexible. The physicochemical properties of 1D nanoparticles, such as size, agglomeration status in liquid and surface charge, play an important role in the ultimate interactions of the CuO nanowires with target cells [26]. The key finding of this work, CuO nanowire/nanoparticles have been employed
Corresponding author. E-mail address: [email protected] (K. Kaviyarasu).
https://doi.org/10.1016/j.jece.2019.103255 Received 3 May 2019; Received in revised form 15 June 2019; Accepted 29 June 2019 Available online 02 July 2019 2213-3437/ © 2019 Elsevier Ltd. All rights reserved.
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
as a vigorous photocatalysts due to its strong chemical stability, abundance and non-toxicity [8]. Sonia et al., revealed that the interaction of hydrocarbons in to CO2 and H2O for catalytic oxidation effective of methylene blue (MB) in waste water treatment [9]. In our research group, we have been reported functionally, we are recommending as the inexpensive method to remove from dye-bearing waste waters for catalytic approach based on organic degradation dyes. Presently, varieties of method were employed for the removal of dyes from contaminated water bodies like active slug, reverse osmosis and electro-chemical oxidation [10]. But scientists and researchers focused CuO nanowire which has excellent property to absorb the dyes from the polluted environment because of the stability against temperature [11]. However, copper oxide nanoparticles act as a good photocatalyst, specifically, CuO nanowires find a special place in photocatalysis under sunlight irradiation. Kasinathan et al., also reported that the effectively discussed by the mechanism of heterogeneous photocatalysis in the presence of TiO2 nanoparticles [12]. In more detail, to understand the systematic revisions are essential to understand the mechanism of behaviour possessions of CuO nanowires were synthesized by hydrothermal method, consequently, it is worthy of future investigation to promote the CuO nanowire were used in different multifunctional production for practical application in terms of health and safety. In this article, we confirm the catalytic stability were carried out to detect the presence of RhB dye the current intensity also observed in visible light, the catalytic behaviour of the CuO nanorods is directly confirms its present report.
Fig. 1. XRD pattern of CuO nanowires.
photoelectron spectrometer (Thermo-VG Scientific, USA) with AlKα (1486.6 eV) as the X-ray source. 3. Results and discussion 3.1. X-ray powder diffraction studies Physical characterization of the prepared CuO nanowire sample using a X-ray diffractometer and CuKα radiation (λ =1.5418 Å) at room temperature. Intensity of the diffracted X-ray beam is recorded as a function of the angle 2θ. The X-ray diffraction pattern (XRD) of CuO nanowires (NWs) as shown in Fig. 1. The samples, there are only twophase groups [Atacamite (Cu2(OH)3Cl)] and [Nantokite (CuCl)], Atacamite is only a copper halide mineral: which is associate with copper (II) chloride hydroxide with formula Cu₂Cl(OH)₃ and no other complex phase were distinguished with in XRD detection limit the challenges of the phase ratios can be reflected from the intensity of thin film and nanopowder vice versa peaks. A very small difference between the miller incides values Orthorhombic (Atacamite) of a = 6.8920; b = 9.0800; c = 6.0550 and Face-centered cubic of (Nantokite) phase which a = 5.4160 respectively prevents us for farsighted shifts conforming to the peaks of Orthorhombic phase group is directed with [JCPDS file no. 00-023-0948]. Moreover, the diffractogram of CuO nanowire is highly comparable to that of copper oxide nanoparticles signifying a well match of crystallographic orientation between thin film and the nanopowder phase reactions, are the lattice mismatching of CuO nanowires have nearly no dissimilarity after compositing [27]. Obviously, the oriented peaks positions are largely extended and the regular crystalline size of CuO nanowire were intended by Scherrer’s equation to be 21 nm and 23 nm. Meanwhile, the sharp peaks (100) & (111) which implies the good crystallinity to confirm that CuO nanowire were effectively performed. Overall, the copper nanowire lengths can be measured by the processing limits such as calcination time and precursor feeding ratios only the difference among thin film deposition and chemical method being the glucose ligands was intriguing [30]. Therefore, we have been experiential that the nanograins raised preferentially in the different columnar axis, the precursor was switched cetyltrimethylammonium bromide (CTAB). Similarly, the preferential growth strain in the columnar edge occurred so dominantly, and the CuO nanowires changed as the portent was switched-over chloride to oxide states [31]. Though, it may be fortuitous the glucose ligands related to the columnar growth and the anionic intensity ligands can be both the columnar and lateral growth as we have discussed in HRTEM the precursor firmness is a vital issue for the directional growth of the grain’s mechanism [28]. Furthermore, CuO nanowire is necessary to elucidate that the growth mechanism of the grain morphology which is specifically rise to the driving force accountable for the progression of nanostructures. The
2. Experimental procedure 2.1. Materials & methods All chemical reagents (analytical grade) were used as received (EMerck 99.99%) without further purification. In this experiment work, to prepare mixed Copper Chloride Hydroxide Hydrate, 0.1Mol % of [Cu7Cl4(OH)10·H2O] and 0.1Mol % of glucose [C6H12O6] were prepared with de-ionized water and 0.5 Mol % cetyltrimethylammonium bromide [CTAB] were prepared separately and then, the latter solution was added gradually in drop wise procedure into the glucose-copper chloride salt solution with vigorous stirring. The colour of the combinations gradually altered from bluish to black green, suggesting the formation of CuO. The resultant solution mixture was loaded into 100 ml Teflon-lined autoclave, which was then filled with distilled water upto 80% of the total volume. The autoclave was sealed and maintained at 170 °C for 9 h. After the reaction was completed, the autoclave was cooled to room temperature, and the resulting solid products were filtered off, washed several times with absolute ethanol and distilled water and then dried at 70 °C for 7 h respectively. 2.2. Sample characterization The X-ray powder diffraction (XRD) experiments were measured on a RigaKu D/max-RB diffractometer with Ni-filtered graphite monochromatized Cukα radiation (λ =1.54056 Å) under 40 kV, 30 mA and scanning between 10° to 90° (2θ). High-resolution transmission electron microscopy (HRTEM) measurements were made on a HITACHI H-8100 electron microscopy (Hitachi, Tokyo, Japan) with an accelerating voltage of 200 kV. The sample for HRTEM characterization was prepared by placing a drop of colloidal solution on carbon-coated copper grid and dried at room temperature. The elemental composition was determined using the selected area electron diffraction (SAED) (IH-300X) analysis was performed at several points in the HRTEM system respectively. A Renishaw micro-Raman spectrometer RM 2000 with IR (632.8 nm) and UV (325 nm) excitation lasers was employed to measure the non-resonant and resonant Raman spectra of CuO nanowire correspondingly. The XPS spectrum was recorded on a ESCALAB 250 2
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
where Knf and Kb are the thermal conductivities at a specified temperature of the suspension and the base fluid [21]. Some studies have demonstrated that the temperature has a great effect on the enhancement of the thermal conductivity for nanofluids. Xie et al. reported that the thermal conductivity enhancement ratios of Cu nanofluids are enhanced considerably when the temperature increases [22]. Fig. 2, shows the relative enhancement of Cu NWRs/H2O at different temperature ranging from 25 °C to 45 °C. At 25 °C, the thermal conductivity enhancement of H2O based Cu nanofluid is less than 10%. When the temperature is increased to 45 °C, the enhancement reaches as large as 40.5%. Brownian motion of the NPs has been proposed as the dominant factor for this phenomenon [23,24] 3.3. Raman spectral analysis The Raman scattering profiles which give further evidence that monoclinic phase is the foremost crystalline edifice in all three marks. Clearly, the Raman scattering exhibited two strong peaks at 246 cm−1, 307 cm−1 and 596 cm−1 where the points at 1517 cm−1 and 1565 cm−1 are signifies to assign the monoclinic orientation of Eg and A1g modes vibration. In the present report we examine, for the first time, the Raman spectra of CuO nanowire as a function of shifting level at three different excitations energies as in Fig. 3 which shows at least the four Raman signatures belongs at 1565 cm−1, 1517 cm−1, 596 cm−1, 307 cm−1 and 246 cm−1 were predicted the first Raman peaks become stronger and sharper, which shows a slightly blue shift and second one being weakest mode of red shift and broadening of Raman shifts increasing with decrease in grain size with vary comparison of vibrational modes of CuO single nanowire the peak position at 246 cm−1 is assigned to be A1g mode and the peak at 307 cm−1 and 596 cm−1 to the Bg vibrational modes of the consequence decides with the literature value of Cu-O matrix [18]. Therefore, the Raman spectra exhibited the difficulties in Fig. 3 it is seen that the O1s XPS is asymmetric, which suggesting that the least two oxygen species are closely extant in the nearby region by the peak about 530 eV is due to oxygen in the CuO crystal lattice which is equivalent to Cu-O bonds, anywhere the peak at 532 eV is due to the chemisorbed oxygen shaped by surface hydroxyl groups which agrees the OeH bonds so far, no report has been concerning that the atomic configuration of Cu and O were rational of Cu:O is closely 1:1 corresponding the XPS results almost showed that the sample is calm of CuO nanowires [19] the Raman peaks develop stronger and sharper, shift somewhat to higher frequencies for example, the peak at 246 cm−1 shifts to 307 cm−1 and 596 cm−1 respectively, which representative that some modification has taken place in the sample, in promise with the XRD results deliberated earlier.
Fig. 2. The measured thermal conductivities of H2O and water-based suspensions containing Cu NWRs at different temperature.
role of the ligands demands to investigate the chemical reactions of CTAB including decomposition rate, adsorption constancy and nuclei formation [29]. In summary, the precursor produced free-standing copper nanowires on surfaces at temperatures below 190 °C without recourse to templates or catalysts.
3.2. Thermal conductivity analysis Thermal conductivity enhancement: with respect to temperature, the measured thermal conductivities of H2O and water-based suspensions containing Cu nanowires (Cu NWRs) with respect to temperature are plotted in Fig. 2. The measured thermal conductivity experienced a gradual growth with temperature rising and reached the highest value at 45 °C. The non-linear trend of thermal conductivity enhancement versus temperature between 25 °C and 45 °C has been often reported, which attributed to various factors including the size, shape, loading of inclusions and the nanoparticle clustering’s. This would change with the variation of temperature, thus there seems to exist an optimum temperature at which the enhancement ratio is maximum. The relative enhancement (η) in percentage of thermal conductivity of Cu NWRs/ H2O nanofluids was calculated by equation (1) and plotted as a function of temperature in Fig. 3, where each data point represents the average enhancement over the range of 25 °C–45 °C. η(%) = 100 x (Knf - Kb)⁄Knf
(1)
3.4. Textural measurements In HRTEM pattern we prescribed more precisely, were annealed at 300 °C for 3 h, typical rod-like morphology of high resolution TEM images of CuO nanowire as shown in Fig. 4(a–l) shows that the result consists of a great quantity of cluster-like nanocrystals were grown at narrow size distribution. When an adding of 0.5 Mol % CTAB and calcination time is 7 h, aggregation of CuO nanocrystals arises which can be clearly distinguished from each other images. When the calcination behaviour has prolonged for 9 h, the morphology turns out to be more regular pattern, and the nanocrystals were exhibited an appropriate morphology Fig. 4(a–d), with the formation existence dispersive. When the calcination time were extended upto 7 to 9 h, the Fig. 4(b–e) that the nanowires are overburnt with an irregular patter formation. Gathering of spherical particles occurs laterally with the formation of monoclinic orientation behaviour; though, the nanocrystals are hard to determine [32]. It may have ensued, because the extended calcination time instigated a collapse of the morphology index. The average particle size of pure Cu sample as shown in Fig. 4(e–g) were measured in
Fig. 3. Raman spectrum of CuO nanowires. 3
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
Fig. 4. TEM images, SAED patterns, HRTEM image, and EDS line-scan profile of the CuO nanowires.
nanowires. In case as shown in Fig. 4(e), which shows very clearly identified the atomic attentiveness proportion between Cu:O was nearby 1:1 stoichiometric fraction, which confirms the nanowire is additionally, to be monitored by the particles size of CuO nanowire is obtainable of the presence of rather or even small percentage of absence is additional stabilizing reagents [34]. In our knowledge, the surface modification of CuO nanoparticles which have entirely bounded with Cu ions as one we can assume the prospect of coordinating Cu and O sites with different nature of ligands like (-Cu) or (−COOH) that can be used for photocatalytic behaviour to enhance the total amount of -O ions which is 4.8 wt% that corresponds to 5.2 wt% of Cu atoms, so the monocrystalline structure which explains the layer-over-layer matrix as in Fig. 4(a&j), Finally, the XRD and SAED profile shows in Fig. 4(i) to confirm the Cu is monocrystalline (111) growth direction which implies the SAED pattern rings were calculated and confirmed as in Fig. 4(l). To end, the XRD, Raman and TEM identification results have confirmed the Ce-O nanowire formation in Cu with O as catalysts at a room temperature [35].
the range of 20 nm - 5 nm though the CuO nanoparticle size in Fig. 4(i) was found in the range of 5 nm - 2 nm. The lattice fringes of Fig. 4(j–l) direct that the CuO nanowire are in good crystalline nature. Mostly, TEM results good in agreement with the XRD data, however, the HRTEM image represents that an individual CuO nanocrystals which is directed, as good crystallinity and rich lattice fringes which is seeming that have regular spherical shapes-rod like nanowire route it consists of 5-2 nm which are agglomerated, cool to form porous asymmetrical networks, though the synthesized nanoparticles consist of monodisperse nanoparticles, as detected in the HRTEM images respectively. In addition, TEM micrographs and selected area electron diffraction (SAED) patterns of the CuO nanocrystals which shown in the Fig. 4(i–k). Diffraction peaks were identically, diffused which signifying the surface is relatively polycrystalline nature [20]. Hence the dispersed pores size, and the mean pore diameter reached from the N2 adsorptiondesorption analysis would epitomise the values of entire structure of samples. The identically matched EDS line-scan profile patterns can be experiential from the HRTEM images that the CuO nanowires have desired range thicknesses around 10 to 30 nm with the horizontal and plan surface studies have a corresponding SAED patterns which clearly specifies, that all the crystalline nanowires with a monoclinic structure with an arbitrary axial crystallographic positionings as shown in Fig. 4(l). Moreover, noticeable whizzing actions were identified in the SAED pattern, which representing the existence of nearly planar imperfections in these CuO nanowires [33]. As can be seen in Fig. 4(d) the measured lattice arrangements of 0.232 and 0.254 nm are reliable with the interplanar spacing values of (111) and (100) planes of pure monoclinic nanocrystal. In this regard, TEM/EDS study which reveals CuO nanowires were produced completely with the even distributions of Cu and O atoms throughout the
3.5. Photocatalytic performance studies CuO is a proficient eco- friendly catalyst, extensively used in the photocatalytic processes which dependence on the particle size and on their shape. Decomposition of synthetic industrial pollutant such as Rhodamine-B (RhB) dye was investigated by the presence of copper oxide nanowires in aqueous dye solution under sunlight. Typically, in this experimental procedure, 50 mg catalyst was dispersed in 100 ml of 20 ppm aqueous RhB solution at preferred neutral pH and irradiated with sunlight. The powder samples were well dispersed in dye solution by constant stirring, followed by the addition of 5 ml of H2O2 (20 wt %), 4
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
which was used as reaction initiator. H2O2 was additional to enhance the formation of more OH% radicals during photodegradation, ensuing the fast decolouration of dye. The catalyst/RhB solution was kept in the dark region for few hours to attain more adsorption-desorption equilibrium constant of account will loss the dye due to during the surface modification [36]. In the dark condition, RhB molecules were dispersed on the catalyst in the mixture solution. The UV–vis absorption spectrum of the CuO/RhB dispersed solution in the dark after 30 min proves that there is no change in the wavelength at 554 nm, which represents that the RhB model pollutant was not degraded in the dark condition [37]. The catalytic-loaded RhB solution were irradiated under sunlight source at 30 min intervals at air environment was eradicated in the maximum mixture solution to sustain the catalyst well dispersed in the mixture solution. At the certain time intervals, we reveal the 2 ml of photo-reacted centrifuged dye solution from the sunlight illuminated dye solution was with-drawn, were studied by the footage of deviations in the absorption UV band spectrum. The characteristic absorption peak of RhB at 554 nm was selected to monitor the photoinduced degradation and the peak intensity was analysed over a period of 150 min. The disintegration of dye was showed by colour mechanism due to pink in the direction of colourless of the solution [38]. The colour changes of the dye solutions become less concentrated as well as with the intensity of absorption band spectrum will decreasing gradually with increasing the equivalent of irradiation time, hope that indicating the strong oxidation peaks of dye has been arisen in the existence of CuO nanoparticles under sunlight irradiation. At regular intervals, the photo assisted degradation of dye reaction was also carried out in different conditions such as in presence of H2O2, only catalyst and blank [39]. All these explanations which showed that CuO nanowires revealed the excellent performance of RhB degradation dye, the total amount of data have been obtained through the catalytic experiments were taken to calculate the degradation efficiency. The photocatalytic activity of CuO nanowires was estimated by the Ct/C0 ratio vs time Fig. 5(a) for the 0.05 g catalyst /100 ml RhB solution [40]. The higher photocatalytic activity of CuO nanowire can be explained based on the
Fig. 6. Representation of proposed mechanism of degradation of RhB.
different particles shape, the modification on the surface and the particles size. Fig. 5(b) represents the time dependent degradation curves of 20 ppm dye molecule in the presence of photocatalyst / H2O2 is nearly ˜ 95% degrade within 150 min. On the other hand, dye solution with catalyst showed comparatively lesser photocatalytic activity (˜70% degradation in the same time). The blank test without catalytic dye under sunlight irradiation time for 3 h was 1.54% and the percentage of photodegradation dye presence of H2O2 is 3.40%, respectively. As well in Fig. 5(c–d) is the plot of (C/C0) vs time. From our experiment, it is noticeable one to identify the concentration of degradation while increasing with the irradiation time and in the presence of hydrogen peroxide, which means to understand, the UV–vis spectra of RhB dye were demonstrated the photocatalytic progress with entails not only for bleaching of solutions in RhB, it is decomposed, because of the intensity of bandwidth spectrum were assigned the formation of
Fig. 5. (a–d): The experimental data of all the samples can be fitted in a straight line which implies that the dye degradation. The plot of C/C0 (and ln(C/C0)) versus time (t) for degradation of RhB dye using only H2O2 action. 5
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
leads to the generation of HO%radical, finally decompose the dye molecules [47].
aromatic rings in the electronic spectra during the time was decreased as shown in Fig. 6. We note that, the oxidation products of CO2, NO3−, SO42-, H+ and H2O were increasing based on the acidity of the solution. So that, the excellent photocatalytic behaviour of the CuO nanowire is very much attributed to the high specific surface separation involved during the reduction of electron-hole recombination pair of ions, which happen due to the morphology of nanowire-shape textures [41]. So that the, a large specific surface volume ratio is beneficial for absorbing electrons and increasing the unsaturated surface coordination angles to improve the photocatalytic behaviour. In the aspect of absorption, the absorbent capacity of CuO nanowire was obviously stronger [42].
CuO+hv → CuO (e−
CB)
+ (h+
VB)
+ H2O → OH
+
CuO (h
VB)
+
CuO (e−
CB)
+ O2→CuO +.-O2
CuO (h
VB)
%
+
−
OH → %OH
RhB+hν (Sunlight) → RhB* RhB* + CuO →RhB%+ + CuO (e–) RhB + (ROS) (O2%– + h+ + HO%) → mineralized products→CO2 + NO2 + H2O
3.6. Reusability of the catalyst The photocatalyst was distinguished from the solution mixture by centrifugation to identify its stability and reusability nature at the end of the photocatalytic process. At each end of the cycle, the catalyst was removed from the solution mixture by simple filtration, washed thoroughly with pure ethanol and dried at 120 °C the dried sample used for new cycles [43]. Decomposition of dye was repeated for 4 cycles, in each reaction process almost 95% of RhB were degraded within 150 min of sunlight irradiation, which indicates that there is no loss of activity of catalyst. So that the results of all the four-cycle were carried out with catalyst are shown in Fig. 7, from these four cycles represents that there is no loss in photocatalytic nature of the same sample with the fresh dye solution. Thus, the driving trials suggest that the practically applicable to explore the nanostructures system for environmental applications such as active sludge, waste water remediation [44]. Decomposition of synthetic organic RhB dye using CuO nanowire semiconductor on illumination of sunlight initially leads to excitation of the semiconductor. On irradiation of sunlight, higher energy level electrons in the conduction band and holes in the valence band are generated [45]. This photogenerated excitons move to the catalyst surface leads to the chemical reaction. Furthermore, the dyes act as a sensitizer of sunlight goes to excited state and eject excited electrons to semiconductors to become a cationic/anion dye free radical followed by self-degradation or degradation by the reactive oxidation species [46]. A crucial mechanism of photocatalytic reaction is depending on the production of electron-hole pairs. These free electrons and holes alter the surrounding oxygen or water molecule into free ·OH radicals. The highly reactive superoxide radical, transferred across significantly. The photo generated holes (h+) in the valence band react with either H2O or −OH to produce the HO· through the following reactions, While the electrons (e−) in the conduction band react with the adsorbed O2 on the CuO nanowire surface to generate according to the following steps, it
Photocatalytic activity was higher for nanowire due to the obtainability of active surface sites are homogeneity in different adsorption which is characteristically different while the specific surface area is increased, due to the exchange interaction between catalyst and dye molecule were associated can be well-known adsorbent occurred. Likewise, it permits to more surface ions to interact activities among the reactive sites, which belongs to the movement of advanced chemical proficiency to the incident photons. So that the similar effects can be beneficial to establishing the large quantity of active sites for the real interface between catalyst and the dye molecule. However, the UV–vis absorption spectrum, which describes the CuO nanowire are a higher volume absorbance spectrum which deals to confirm the prominent role of interaction between CuO and dye [48]. Foremost, above the results to coordinate which enhance the active surface area which is existing of the catalytic activity is distinguished significantly which enhance the dimension of the matrix has been deducted. Moreover, because of the irrespective nanostructures would be defined a quantum confinement of optically excited carrier’s electrons. So that the QC effect which plays an important role of photo-induced charge degradation effect of organic dyes which may be due to occur the active contribution of quantum confined excitons [49]. Moreover, the quantum confined excitons or optically excited carrier’s ions are not restricted to move over the photocatalysts of CuO nanowire [13,14]. As a result, decreasing crystallite size can also increasing the oxidation potential thereby photoconductivity of the resulted material is enhanced by the narrow bandgap of the CuO nanowires, among the recombination effects of photogenerated electron/ holes lifetime of photogenerated electrons is also prolonged, so that the rod exhibits which higher photocatalytic activity to confirm the our photocatalysis results, among all the reports, not only relates to the surface adsorption ability, but also related to the oxygen defects on the surface area [15–17]. We are noted, that the observed nanowires which enriched the higher catalytic activity to comparing the other neighbouring morphologies [50]. So that the, larger surface volume ratios, are more adsorption rate, which belongings the great charge separation between the electrons/holes in CuO nanowires to established more nanowires are favourable to support above the analysis chart would conclude the stability of active surface area, so that the, catalytic mechanism we expected to confirm the quantum confinement of photoinduced carriers with different morphology, therefore, the photocatalytic activity can be reported in the possibility of ions mechanism which intermediate by-products of RhB were N,N-diethylrhodamine, Nethylrhodamine, 3-hydroxybenzoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid and adipic acid as shown in Fig. 8. Based on these intermediate compounds, to estimate the catalytic degradation pathway of RhB dye were proposed to determine our own views, via two competitive processes; which is (i) N-demethylation and destruction of the conjugated structure and conclude the study that chromophore cleavage, ring opening, and mineralization were the main photocatalytic degradation pathways of RhB dye. (ii) The dye was converted to smaller organic species and ultimately mineralized
Fig. 7. Decomposition of dye was repeated for 4 cycles represents that there is no loss in photocatalytic nature of the same sample with the fresh dye solution. 6
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
Fig. 8. Schematic mechanism of photocatalytic nature of the same sample with the fresh dye solution.
together with other organic groups to inorganic bi-products (e.g., CO2 and water). [10]
4. Conclusion [11]
In summary, all the studies, were shown the copper oxide nanowires which displays a higher volume surface redox activity either or nor the parent single oxides were prepared by the hydrothermal method. So that the degree of compositional heterogeneity pattern of specimen was surface enrichment with Cu ions is ascribable to promote the different relative reports to discuss the precipitation of -O and -Cu atoms. In addition, the CuO nanowire is the surfactant of nature were used to play an important role of reducing agent against the transition phase index from our XRD, HRTEM and micro-Raman results were reported systematically.
[12]
[13]
[14]
[15]
References [16] [1] H.D. Hill, C.A. Mirkin, The bio-barcode assay for the edetection of protein and nucleic acid targets uding DTT-induced ligand exchange, Nat. Protoc. 1 (1) (2006) 324–336. [2] H.D. Hill, R.A. Vega, Nonenzymatic detection of bacterial genomic DNA using the bio bar code assay, Anal. Chem. 79 (23) (2007) 9218–9223. [3] I. Faheem, S. Sammia, A.K. Shakeel, Green synthesis of copper oxide nanoparticles using Abutilon indicum leaf extract: antimicrobial, antioxidant and photocatalytic dye degradation activities, Trop. J. Pharm. Res. 16 (2016) 743–753. [4] S. Yallappa, J. Manjanna, M.A. Sindhe, Microwave assisted rapid synthesis and biological evaluation of stable copper nanoparticles using T. Arjuna bark extract, Spectrochim Acta Mol Biomol Spectrosc. 110 (2013) 108–115. [5] R. Seigneuric, L. Markey, D.S.A. Nuyten, From nanotechnology to nanomedicine: applications to cancer research, Curr. Mol. Med. 10 (2010) 640–652. [6] H. Wang, Q. Pan, J. Zhao, G. Yin, P. Zuo, Fabrication of CuO film with network like architectures through solution-immersion and their application in lithium ion batteries, J. Power Sources 167 (2007) 206. [7] J. Lasek, Y. Yu, J.C.S. Wu, Removal of NOx by photocatalytic processes, J. Photochem. Photobiol. C: Photochem. Rev. 14 (2013) 29. [8] M. Zhu, G. Diao, High catalytic activity of CuO nanorods for oxidation of cyclohexane to 2-cyclohexene-1-one, Catal. Sci. Technol. 2 (2012) 82. [9] S. Sonia, S. Poongodi, P. Suresh Kumar, D. Mangalraj, N. Ponpandian,
[17]
[18] [19] [20]
[21]
[22] [23]
[24]
7
C. Viswanathan, Hydrothermal synthesis of highly stable CuO nanostructures for efficient photocatalytic degradation of organic dyes, Mater. Sci. Semicond. Process. 30 (2015) 585. S.H. Kim, A. Umar, R. Kumar, A.A. Ibrahim, G. Kumar, Facile synthesis and photocatalytic activity of cocoon shaped CuO nanostructures, Mater. Lett. 156 (2015) 138–141. A. Angel Ezhilarasi, J. Judith Vijaya, K. Kaviyarasu, M. Maaza, A. Ayeshamariam, L. John Kennedy, Green synthesis of NiO nanoparticles using Moringa oleifera extract and their biomedical applications: cytotoxicity effect of nanoparticles against HT-29 cancer cells, J. Photochem. Photobiol. B, Biol. 164 (2016) 352–360. K. Kasinathan, J. Kennedy, M. Elayaperumal, M. Henini, M. Malik, Photodegradation of organic pollutants RhB dye using UV simulated sunlight on ceria based TiO2 nanomaterials for antibacterial applications, Sci. Rep. 6 (2016) 38064. M. Kaur, K.P. Muthe, S.K. Despande, S. Choudhury, J.B. Singh, V. Neetika, S.K. Gupta, J.V. Yakhmi, Growth and branching of CuO nanowires by thermal oxidation, J. Cryst. Growth 289 (2006) 670–675. Yi-kun Su, S. Cheng-Min, H. Yang, Hu Li, G. Hong Ju, Controlled synthesis of highly ordered CuO nanowire arrays by template-based sol-gel route, Trans. Nonferrous Met. SOC. China 17 (2007) 783–786. C. Xu, Y. Lin, G. Xu, G. Wang, Preparation and characterization of CuO nanorods by thermal decomposition of CuC2O4 precursor, Mater. Res. Bull. 7 (2002) 2365–2372. J. Moulder, W. Sticke, P. Sobol, K. Bomben, Handbook of X-ray photoelectron spectroscopy, in: J. Chastain (Ed.), Standard ESCA Spectra of the Elements and Line Energy Information, Perkin Elmer Corporation: Physical Electronics Division, USA, 1992. C.D. Wagner, W.M. Riggs, L.E. Davis, J.F. Moulder, G.E. Muilenberg, Handbook of X-ray Photoelectron Spectroscopy Perkin-Elmer Corp. Physical Electronics Division, Eden Prairie, Minnesota, USA, 1979, p. 190. J.C. Irwin, J. Chrzanowski, T. Wei, Raman scattering investigation of Cu18O, Phys. C 166 (1990) 456. J.F. Xu, W. Ji, X. Shen, S.H. Tang, Preparation and characterization of CuO nanocrystals, J. Solid State Chem. 147 (1999) 516–519. C. Shao Liang, C. Ming Feng, Fabrication, characterization, and kinetic study of vertical single-crystalline CuO nanowires on Si substrates, Nanoscale Res. Lett. 7 (1) (2012) 119. Touria Khamliche, Saleh Khamlich, Terry B. Doyle, Daniel Makinde, Malik Maaza, Thermal conductivity enhancement of nano-silver particles dispersed ethylene glycol based nanofluids, Mater. Res. Exp. 05 (2018) 035020. Huaqing Xie, Wei Yu, Yang Li, Lifei Chen Discussion on the thermal conductivity enhancement of nanofluids, Nanoscale Res. Lett. 6 (2011) 124. R. Prasher, P. Bhattacharya, P.E. Phelan, Brownian motion-based convective-conductive model for the effective thermal conductivity of nanofluids ASME, J. Heat Transfer 128 (2005) 588–595. R. Shukla, V.K. Kand Dhir, Effect of brownian motion on thermal conductivity of
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
nanofluids ASME J, Heat Transfer. 130 (2008) 042406. [25] T. Itoh, K. Kojima, H. Shimomoto, E. Ihara, Control of lengths and densities of surface-attached chains on polymer particles prepared by dispersion polymerization using macromonomer stabilizer, Polymer 158 (2018) 158–165. [26] M.M. Sabzehmeidani, H. Karimi, M. Ghaedi, Sonophotocatalytic treatment of rhodamine B using visible-light-driven CeO2/Ag2CrO4 composite in a batch mode based on ribbon-like CeO2 nanofibers via electrospinning, Environ. Sci. Pollut. Res. Int. 26 (8) (2019) 8050–8068. [27] K. Kaviyarasu, P.A. Devarajan, A convenient route to synthesize hexagonal pillar shaped ZnO nanoneedles via CTAB surfactant, Adv. Mat. Lett. 4 (7) (2013) 582–585. [28] S.K. Jesudoss, J. Judith Vijaya, P. Iyyappa Rajan, K. Kaviyarasu, M. Sivachidambaram, L. John Kennedy, Hamad A. Al-Lohedan, R. Jothiramalingam, Murugan A. Munusamy, High performance multifunctional green Co3O4 spinel nanoparticles: photodegradation of textile dye effluents, catalytic hydrogenation of nitro-aromatics and antibacterial studies, Photochem. Photobiol. Sci. 16 (5) (2017) 766–778. [29] K. Kaviyarasu, A. Raja, P.A. Devarajan, Structural elucidation and spectral characterizations of Co3O4 nanoflakes, Spectrochim. Acta A. Mol. Biomol. Spectrosc. 114 (2013) 586–591. [30] P. Iyyappa Rajan, J. Judith Vijaya, S.K. Jesudoss, K. Kaviyarasu, L. John Kennedy, R. Jothiramalingam, Hamad A. Al-Lohedan, Mansoor-Ali Vaali-Mohammed, Greenfuel-mediated synthesis of self-assembled NiO nano-sticks for dual applications—photocatalytic activity on Rose Bengal dye and antimicrobial action on bacterial strains, Mater. Res. Express 4 (8) (2017) 085030. [31] Sowmya Sri Rathnakumar, Kana Noluthando, Arockia Jayalatha Kulandaiswamy, John Bosco Balaguru Rayappan, Kaviyarasu Kasinathan, John Kennedy, Malik Maaza, Stalling behaviour of chloride ions: a non-enzymatic electrochemical detection of α-Endosulfan using CuO interface, Sens. Actuators B Chem. 293 (2019) 100–106. [32] D. Saravanakkumar, S. Sivaranjani, K. Kaviyarasu, A. Ayeshamariam, B. Ravikumar, S. Pandiarajan, C. Veeralakshmi, M. Jayachandran, M. Maaza, Synthesis and characterization of ZnO-CuO nanocomposites powder by modified perfume spray pyrolysis method and its antimicrobial investigation, J. Semicond. 39 (3) (2018) 033001. [33] C. Maria Magdalane, K. Kaviyarasu, J. Judith Vijaya, B. Siddhardha, B. Jeyaraj, J. Kennedy, M. Maaza, Evaluation on the heterostructured CeO2/Y2O3 binary metal oxide nanocomposites for UV/Vis light induced photocatalytic degradation of Rhodamine - B dye for textile engineering application, J. Alloys. Compd. 727 (2017) 1324–1337. [34] C.M. Magdalane, K. Kaviyarasu, J.J. Vijaya, B. Siddhardha, B. Jeyaraj, Facile synthesis of heterostructured cerium oxide/yttrium oxide nanocomposite in UV light induced photocatalytic degradation and catalytic reduction: synergistic effect of antimicrobial studies, J. Photochem. Photobiol. B, Biol. 173 (2017) 23–34. [35] K. Anand, K. Kaviyarasu, Sudhakar Muniyasamy, Selvaraj Mohana Roopan, R.M. Gengan, A.A. Chuturgoon, Bio-Synthesis of Silver Nanoparticles Using Agroforestry Residue and Their Catalytic Degradation for Sustainable Waste Management, J. Clust. Sci. 28 (2017) 2279–2291. [36] K. Kasinathan, J. Kennedy, M. Elayaperumal, M. Henini, M. Malik, Photodegradation of organic pollutants RhB dye using UV simulated sunlight on ceria based TiO2 nanomaterials for antibacterial applications, Sci. Rep. 6 (2016) 38064. [37] K. Kaviyarasu, A. Ayeshamariam, E. Manikandan, J. Kennedy, R. Ladchumananandasivam, Uilame Umbelino Gomes, M. Jayachandran, M. Maaza,
[38]
[39]
[40]
[41]
[42]
[43]
[44]
[45]
[46]
[47]
[48]
[49]
[50]
8
Solution processing of CuSe quantum dots: photocatalytic activity under RhB for UV and visible-light solar irradiation, Mater. Sci. Eng. B 210 (2016) 1–9. K. Kaviyarasu, E. Manikandan, J. Kennedy, M. Jayachandran, R. Ladchumananandasiivam, U. Umbelino De Gomes, M. Maaza, Synthesis and characterization studies of NiO nanorods for enhancing solar cell efficiency using photon upconversion materials, Ceram. Int. 42 (7) (2016) 8385–8394. K. Kaviyarasu, C. Maria Magdalane, E. Manikandan, M. Jayachandran, R. Ladchumananandasivam, S. Neelamani, M. Maaza, Well-aligned graphene oxide nanosheets decorated with zinc oxide nanocrystals for high performance photocatalytic application, Int. J. Nanosci. 14 (03) (2015) 1550007. K. Kaviyarasu, C.M. Magdalane, K. Anand, E. Manikandan, M. Maaza, Synthesis and characterization studies of MgO:CuO nanocrystals by wet-chemical method, Spectrochim. Acta A. Mol. Biomol. Spectrosc. 142 (2015) 405–409. K. Kaviyarasu, E. Manikandan, J. Kennedy, M. Maaza, A comparative study on the morphological features of highly ordered MgO: AgO nanocube arrays prepared via a hydrothermal method, RSC Adv. 5 (100) (2015) 82421–82428. K. Kaviyarasu, C. Maria Magdalane, K. Kanimozhi, J. Kennedy, B. Siddhardha, E. Subba Reddy, Naresh Kumar Rotte, Chandra Shekhar Sharma, F.T. Thema, Douglas Letsholathebe, Genene Tessema Mola, M. Maaza, Elucidation of photocatalysis, photoluminescence and antibacterial studies of ZnO thin films by spin coating method, J. Photochem. Photobiol. B, Biol. 173 (2017) 466–475. C. Maria Magdalane, K. Kaviyarasu, J. Judith Vijaya, B. Siddhardha, B. Jeyaraj, Photocatalytic activity of binary metal oxide nanocomposites of CeO2/CdO nanospheres: investigation of optical and antimicrobial activity, J. Photochem. Photobiol. B, Biol. 163 (2016) 77–86. K. Kaviyarasu, L. Kotsedi, A. Simo, X. Fuku, G.T. Mola, J. Kennedy, M. Maaza, Photocatalytic activity of ZrO2 doped lead dioxide nanocomposites: investigation of structural and optical microscopy of RhB organic dye, Appl. Surf. Sci. 421 (2017) 234–239. C. Maria Magdalane, K. Kaviyarasu, J. Judith Vijaya, C. Jayakumar, M. Maaza, B. Jeyaraj, Photocatalytic degradation effect of malachite green and catalytic hydrogenation by UV–illuminated CeO2/CdO multilayered nanoplatelet arrays: investigation of antifungal and antimicrobial activities, J. Photochem. Photobiol. B, Biol. 169 (2017) 110–123. X. Fuku, K. Kaviyarasu, N. Matinise, M. Maaza, Punicalagin green functionalized Cu/Cu2O/ZnO/CuO nanocomposite for potential electrochemical transducer and catalyst, Nanoscale Res. Lett. 11 (1) (2016) 386. S.K. Jesudoss, J. Judith Vijaya, L. John Kennedy, P. Iyyappa Rajan, Hamad A. AlLohedan, R. Jothi Ramalingam, K. Kaviyarasu, M. Bououdina, Studies on the efficient dual performance of Mn1–xNixFe2O4 spinel nanoparticles in photodegradation and antibacterial activity, J. Photochem. Photobiol. B, Biol. 165 (2016) 121–132. X. Fuku, N. Matinise, M. Masikini, K. Kasinathan, M. Maaza, An electrochemically active green synthesized polycrystalline NiO/MgO catalyst: use in photo-catalytic applications, Mater. Res. Bull. 97 (2018) 457–465. A. Raja, S. Ashokkumar, R. Pavithra Marthandam, J. Jayachandiran, Chandra Prasad Khatiwada, K. Kaviyarasu, R. Ganapathi Raman, M. Swaminathan, Ecofriendly preparation of zinc oxide nanoparticles using Tabernaemontana divaricata and its photocatalytic and antimicrobial activity, J. Photochem. Photobiol. B, Biol. 181 (2018) 53–58. Y.S. Reddy, C.M. Magdalane, K. Kaviyarasu, G.T. Mola, J. Kennedy, M. Maaza, Equilibrium and kinetic studies of the adsorption of acid blue 9 and Safranin O from aqueous solutions by MgO decked FLG coated Fuller’s earth, J. Phys. Chem. Solids 123 (2018) 43–51.
Contents lists available at ScienceDirect
Journal of Environmental Chemical Engineering journal homepage: www.elsevier.com/locate/jece
Stability and thermal conductivity of CuO nanowire for catalytic applications
T
⁎
Noluthando Kanaa,b, K. Kaviyarasua,b, , T. Khamlichea,b, C. Maria Magdalanec,d, M. Maazaa,b a
UNESO-UNISA Africa Chair in Nanosciences/Nanotechnology Laboratories, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria, South Africa b Nanosciences African Network (NANOAFNET), Materials Research Department (MRD), iThemba LABS-National Research Foundation (NRF), P O Box 722, Somerset West, Western Cape Province, South Africa c Department of Chemistry, St. Xavier’s College (Autonomous), Tirunelveli, 627002, India d LIFE, Department of Chemistry, Loyola College (Autonomous), Chennai, 600034, India
A R T I C LE I N FO
A B S T R A C T
Keywords: CuO nanowire Structural parameters Thermal conductivity enhancement Catalytic applications Electron microscopy
Copper oxide (CuO) nanowire is an interesting material because of the versatile application of photocatalytic phase transition were investigated by the presence of Rhodamine-B (RhB) dye under sunlight irradiation. In this view, CuO nanowire is critical to elucidate the growth mechanism of grain morphology which is specifically rise to the driving force accountable for the progression of 2D nanostructures. Among, the role of the ligands, were determined the chemical mechanism of CTAB including decomposition rate, adsorption constancy and nuclei formation etc. We have confirmed the non-linear trends of the thermal conductivity were enhanced between 25 to 45 °C, which attributes the various factors of the size and shape of the nanoparticles. On the other hand, the Raman studies were exhibited the strong peaks at 246 cm−1, 307 cm−1 and 596 cm−1 where the points at 1517 cm−1 and 1565 cm−1 are signifies to assign the monoclinic orientation of Eg and A1g modes vibration. The photocatalyst were distinguished from the solution mixture by centrifugation to identify its stability and reusability nature at the end of the photocatalytic process. At each end of every cycle, the catalyst was removed from the solution mixture by simple filtration, washed thoroughly with pure ethanol and dried at 120 °C the dried sample used for new cycles. Thus, the driving trials suggest that the practically applicable to explore the nanostructures system for environmental applications such as active sludge, waste water remediation.
1. Introduction We account here on the primary focus of the growth morphology of high-yield, vertical CuO nanowires were produced by hydrothermal technique and the length of the CuO nanowires could be changed from several to tens of nanometres by regulating the oxidation temperature and time respectively [1]. In this view, fully-fledged CuO nanowires were persevering to be single-crystalline with different axial crystallographic orientations [2]. Remarkably, we have been efforts to synthesize CuO nanowire with considerable success, but we are largely limited to morphological structures ranges from 10 to 5 nm size compared to great deal with biological molecules for example enzymes, receptors among others and so on [3]. In addition, due to the structural stability of Cu ions which can be interact with bioluminescence molecules and it has suitable in diagnosis for cancer treatment [4,5]. Depending on the medical condition, of these CuO nanowire are very firm and their activity is extensively when linked with an α-endosulfan ⁎
molecules, it seems like, CuO nanowires were grown different directions, however copper ions accumulating together to solve the difficulties of poor ionic conduction and the deficient volume retention which existing in nanoparticles not like bulk counterpart [6]. Moreover, Synthesis of CuO nanowires is very less expensive when compared to gold and silver nanoparticles whish possess excellent antimicrobial agent because of their unusual crystal orientation, but now-a-days recent researchers have focused on green routes for the synthesis and production of nanoparticles extensively [7]. Green synthesis is one of the simplest and easiest methods for synthesis of these nanoparticles are very stable, and their activity is longer when compared with organic anti-microbial agents also [25]. The advantage of producing like these CuO nanowires it is easy, fast, cost effective and flexible. The physicochemical properties of 1D nanoparticles, such as size, agglomeration status in liquid and surface charge, play an important role in the ultimate interactions of the CuO nanowires with target cells [26]. The key finding of this work, CuO nanowire/nanoparticles have been employed
Corresponding author. E-mail address: [email protected] (K. Kaviyarasu).
https://doi.org/10.1016/j.jece.2019.103255 Received 3 May 2019; Received in revised form 15 June 2019; Accepted 29 June 2019 Available online 02 July 2019 2213-3437/ © 2019 Elsevier Ltd. All rights reserved.
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
as a vigorous photocatalysts due to its strong chemical stability, abundance and non-toxicity [8]. Sonia et al., revealed that the interaction of hydrocarbons in to CO2 and H2O for catalytic oxidation effective of methylene blue (MB) in waste water treatment [9]. In our research group, we have been reported functionally, we are recommending as the inexpensive method to remove from dye-bearing waste waters for catalytic approach based on organic degradation dyes. Presently, varieties of method were employed for the removal of dyes from contaminated water bodies like active slug, reverse osmosis and electro-chemical oxidation [10]. But scientists and researchers focused CuO nanowire which has excellent property to absorb the dyes from the polluted environment because of the stability against temperature [11]. However, copper oxide nanoparticles act as a good photocatalyst, specifically, CuO nanowires find a special place in photocatalysis under sunlight irradiation. Kasinathan et al., also reported that the effectively discussed by the mechanism of heterogeneous photocatalysis in the presence of TiO2 nanoparticles [12]. In more detail, to understand the systematic revisions are essential to understand the mechanism of behaviour possessions of CuO nanowires were synthesized by hydrothermal method, consequently, it is worthy of future investigation to promote the CuO nanowire were used in different multifunctional production for practical application in terms of health and safety. In this article, we confirm the catalytic stability were carried out to detect the presence of RhB dye the current intensity also observed in visible light, the catalytic behaviour of the CuO nanorods is directly confirms its present report.
Fig. 1. XRD pattern of CuO nanowires.
photoelectron spectrometer (Thermo-VG Scientific, USA) with AlKα (1486.6 eV) as the X-ray source. 3. Results and discussion 3.1. X-ray powder diffraction studies Physical characterization of the prepared CuO nanowire sample using a X-ray diffractometer and CuKα radiation (λ =1.5418 Å) at room temperature. Intensity of the diffracted X-ray beam is recorded as a function of the angle 2θ. The X-ray diffraction pattern (XRD) of CuO nanowires (NWs) as shown in Fig. 1. The samples, there are only twophase groups [Atacamite (Cu2(OH)3Cl)] and [Nantokite (CuCl)], Atacamite is only a copper halide mineral: which is associate with copper (II) chloride hydroxide with formula Cu₂Cl(OH)₃ and no other complex phase were distinguished with in XRD detection limit the challenges of the phase ratios can be reflected from the intensity of thin film and nanopowder vice versa peaks. A very small difference between the miller incides values Orthorhombic (Atacamite) of a = 6.8920; b = 9.0800; c = 6.0550 and Face-centered cubic of (Nantokite) phase which a = 5.4160 respectively prevents us for farsighted shifts conforming to the peaks of Orthorhombic phase group is directed with [JCPDS file no. 00-023-0948]. Moreover, the diffractogram of CuO nanowire is highly comparable to that of copper oxide nanoparticles signifying a well match of crystallographic orientation between thin film and the nanopowder phase reactions, are the lattice mismatching of CuO nanowires have nearly no dissimilarity after compositing [27]. Obviously, the oriented peaks positions are largely extended and the regular crystalline size of CuO nanowire were intended by Scherrer’s equation to be 21 nm and 23 nm. Meanwhile, the sharp peaks (100) & (111) which implies the good crystallinity to confirm that CuO nanowire were effectively performed. Overall, the copper nanowire lengths can be measured by the processing limits such as calcination time and precursor feeding ratios only the difference among thin film deposition and chemical method being the glucose ligands was intriguing [30]. Therefore, we have been experiential that the nanograins raised preferentially in the different columnar axis, the precursor was switched cetyltrimethylammonium bromide (CTAB). Similarly, the preferential growth strain in the columnar edge occurred so dominantly, and the CuO nanowires changed as the portent was switched-over chloride to oxide states [31]. Though, it may be fortuitous the glucose ligands related to the columnar growth and the anionic intensity ligands can be both the columnar and lateral growth as we have discussed in HRTEM the precursor firmness is a vital issue for the directional growth of the grain’s mechanism [28]. Furthermore, CuO nanowire is necessary to elucidate that the growth mechanism of the grain morphology which is specifically rise to the driving force accountable for the progression of nanostructures. The
2. Experimental procedure 2.1. Materials & methods All chemical reagents (analytical grade) were used as received (EMerck 99.99%) without further purification. In this experiment work, to prepare mixed Copper Chloride Hydroxide Hydrate, 0.1Mol % of [Cu7Cl4(OH)10·H2O] and 0.1Mol % of glucose [C6H12O6] were prepared with de-ionized water and 0.5 Mol % cetyltrimethylammonium bromide [CTAB] were prepared separately and then, the latter solution was added gradually in drop wise procedure into the glucose-copper chloride salt solution with vigorous stirring. The colour of the combinations gradually altered from bluish to black green, suggesting the formation of CuO. The resultant solution mixture was loaded into 100 ml Teflon-lined autoclave, which was then filled with distilled water upto 80% of the total volume. The autoclave was sealed and maintained at 170 °C for 9 h. After the reaction was completed, the autoclave was cooled to room temperature, and the resulting solid products were filtered off, washed several times with absolute ethanol and distilled water and then dried at 70 °C for 7 h respectively. 2.2. Sample characterization The X-ray powder diffraction (XRD) experiments were measured on a RigaKu D/max-RB diffractometer with Ni-filtered graphite monochromatized Cukα radiation (λ =1.54056 Å) under 40 kV, 30 mA and scanning between 10° to 90° (2θ). High-resolution transmission electron microscopy (HRTEM) measurements were made on a HITACHI H-8100 electron microscopy (Hitachi, Tokyo, Japan) with an accelerating voltage of 200 kV. The sample for HRTEM characterization was prepared by placing a drop of colloidal solution on carbon-coated copper grid and dried at room temperature. The elemental composition was determined using the selected area electron diffraction (SAED) (IH-300X) analysis was performed at several points in the HRTEM system respectively. A Renishaw micro-Raman spectrometer RM 2000 with IR (632.8 nm) and UV (325 nm) excitation lasers was employed to measure the non-resonant and resonant Raman spectra of CuO nanowire correspondingly. The XPS spectrum was recorded on a ESCALAB 250 2
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
where Knf and Kb are the thermal conductivities at a specified temperature of the suspension and the base fluid [21]. Some studies have demonstrated that the temperature has a great effect on the enhancement of the thermal conductivity for nanofluids. Xie et al. reported that the thermal conductivity enhancement ratios of Cu nanofluids are enhanced considerably when the temperature increases [22]. Fig. 2, shows the relative enhancement of Cu NWRs/H2O at different temperature ranging from 25 °C to 45 °C. At 25 °C, the thermal conductivity enhancement of H2O based Cu nanofluid is less than 10%. When the temperature is increased to 45 °C, the enhancement reaches as large as 40.5%. Brownian motion of the NPs has been proposed as the dominant factor for this phenomenon [23,24] 3.3. Raman spectral analysis The Raman scattering profiles which give further evidence that monoclinic phase is the foremost crystalline edifice in all three marks. Clearly, the Raman scattering exhibited two strong peaks at 246 cm−1, 307 cm−1 and 596 cm−1 where the points at 1517 cm−1 and 1565 cm−1 are signifies to assign the monoclinic orientation of Eg and A1g modes vibration. In the present report we examine, for the first time, the Raman spectra of CuO nanowire as a function of shifting level at three different excitations energies as in Fig. 3 which shows at least the four Raman signatures belongs at 1565 cm−1, 1517 cm−1, 596 cm−1, 307 cm−1 and 246 cm−1 were predicted the first Raman peaks become stronger and sharper, which shows a slightly blue shift and second one being weakest mode of red shift and broadening of Raman shifts increasing with decrease in grain size with vary comparison of vibrational modes of CuO single nanowire the peak position at 246 cm−1 is assigned to be A1g mode and the peak at 307 cm−1 and 596 cm−1 to the Bg vibrational modes of the consequence decides with the literature value of Cu-O matrix [18]. Therefore, the Raman spectra exhibited the difficulties in Fig. 3 it is seen that the O1s XPS is asymmetric, which suggesting that the least two oxygen species are closely extant in the nearby region by the peak about 530 eV is due to oxygen in the CuO crystal lattice which is equivalent to Cu-O bonds, anywhere the peak at 532 eV is due to the chemisorbed oxygen shaped by surface hydroxyl groups which agrees the OeH bonds so far, no report has been concerning that the atomic configuration of Cu and O were rational of Cu:O is closely 1:1 corresponding the XPS results almost showed that the sample is calm of CuO nanowires [19] the Raman peaks develop stronger and sharper, shift somewhat to higher frequencies for example, the peak at 246 cm−1 shifts to 307 cm−1 and 596 cm−1 respectively, which representative that some modification has taken place in the sample, in promise with the XRD results deliberated earlier.
Fig. 2. The measured thermal conductivities of H2O and water-based suspensions containing Cu NWRs at different temperature.
role of the ligands demands to investigate the chemical reactions of CTAB including decomposition rate, adsorption constancy and nuclei formation [29]. In summary, the precursor produced free-standing copper nanowires on surfaces at temperatures below 190 °C without recourse to templates or catalysts.
3.2. Thermal conductivity analysis Thermal conductivity enhancement: with respect to temperature, the measured thermal conductivities of H2O and water-based suspensions containing Cu nanowires (Cu NWRs) with respect to temperature are plotted in Fig. 2. The measured thermal conductivity experienced a gradual growth with temperature rising and reached the highest value at 45 °C. The non-linear trend of thermal conductivity enhancement versus temperature between 25 °C and 45 °C has been often reported, which attributed to various factors including the size, shape, loading of inclusions and the nanoparticle clustering’s. This would change with the variation of temperature, thus there seems to exist an optimum temperature at which the enhancement ratio is maximum. The relative enhancement (η) in percentage of thermal conductivity of Cu NWRs/ H2O nanofluids was calculated by equation (1) and plotted as a function of temperature in Fig. 3, where each data point represents the average enhancement over the range of 25 °C–45 °C. η(%) = 100 x (Knf - Kb)⁄Knf
(1)
3.4. Textural measurements In HRTEM pattern we prescribed more precisely, were annealed at 300 °C for 3 h, typical rod-like morphology of high resolution TEM images of CuO nanowire as shown in Fig. 4(a–l) shows that the result consists of a great quantity of cluster-like nanocrystals were grown at narrow size distribution. When an adding of 0.5 Mol % CTAB and calcination time is 7 h, aggregation of CuO nanocrystals arises which can be clearly distinguished from each other images. When the calcination behaviour has prolonged for 9 h, the morphology turns out to be more regular pattern, and the nanocrystals were exhibited an appropriate morphology Fig. 4(a–d), with the formation existence dispersive. When the calcination time were extended upto 7 to 9 h, the Fig. 4(b–e) that the nanowires are overburnt with an irregular patter formation. Gathering of spherical particles occurs laterally with the formation of monoclinic orientation behaviour; though, the nanocrystals are hard to determine [32]. It may have ensued, because the extended calcination time instigated a collapse of the morphology index. The average particle size of pure Cu sample as shown in Fig. 4(e–g) were measured in
Fig. 3. Raman spectrum of CuO nanowires. 3
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
Fig. 4. TEM images, SAED patterns, HRTEM image, and EDS line-scan profile of the CuO nanowires.
nanowires. In case as shown in Fig. 4(e), which shows very clearly identified the atomic attentiveness proportion between Cu:O was nearby 1:1 stoichiometric fraction, which confirms the nanowire is additionally, to be monitored by the particles size of CuO nanowire is obtainable of the presence of rather or even small percentage of absence is additional stabilizing reagents [34]. In our knowledge, the surface modification of CuO nanoparticles which have entirely bounded with Cu ions as one we can assume the prospect of coordinating Cu and O sites with different nature of ligands like (-Cu) or (−COOH) that can be used for photocatalytic behaviour to enhance the total amount of -O ions which is 4.8 wt% that corresponds to 5.2 wt% of Cu atoms, so the monocrystalline structure which explains the layer-over-layer matrix as in Fig. 4(a&j), Finally, the XRD and SAED profile shows in Fig. 4(i) to confirm the Cu is monocrystalline (111) growth direction which implies the SAED pattern rings were calculated and confirmed as in Fig. 4(l). To end, the XRD, Raman and TEM identification results have confirmed the Ce-O nanowire formation in Cu with O as catalysts at a room temperature [35].
the range of 20 nm - 5 nm though the CuO nanoparticle size in Fig. 4(i) was found in the range of 5 nm - 2 nm. The lattice fringes of Fig. 4(j–l) direct that the CuO nanowire are in good crystalline nature. Mostly, TEM results good in agreement with the XRD data, however, the HRTEM image represents that an individual CuO nanocrystals which is directed, as good crystallinity and rich lattice fringes which is seeming that have regular spherical shapes-rod like nanowire route it consists of 5-2 nm which are agglomerated, cool to form porous asymmetrical networks, though the synthesized nanoparticles consist of monodisperse nanoparticles, as detected in the HRTEM images respectively. In addition, TEM micrographs and selected area electron diffraction (SAED) patterns of the CuO nanocrystals which shown in the Fig. 4(i–k). Diffraction peaks were identically, diffused which signifying the surface is relatively polycrystalline nature [20]. Hence the dispersed pores size, and the mean pore diameter reached from the N2 adsorptiondesorption analysis would epitomise the values of entire structure of samples. The identically matched EDS line-scan profile patterns can be experiential from the HRTEM images that the CuO nanowires have desired range thicknesses around 10 to 30 nm with the horizontal and plan surface studies have a corresponding SAED patterns which clearly specifies, that all the crystalline nanowires with a monoclinic structure with an arbitrary axial crystallographic positionings as shown in Fig. 4(l). Moreover, noticeable whizzing actions were identified in the SAED pattern, which representing the existence of nearly planar imperfections in these CuO nanowires [33]. As can be seen in Fig. 4(d) the measured lattice arrangements of 0.232 and 0.254 nm are reliable with the interplanar spacing values of (111) and (100) planes of pure monoclinic nanocrystal. In this regard, TEM/EDS study which reveals CuO nanowires were produced completely with the even distributions of Cu and O atoms throughout the
3.5. Photocatalytic performance studies CuO is a proficient eco- friendly catalyst, extensively used in the photocatalytic processes which dependence on the particle size and on their shape. Decomposition of synthetic industrial pollutant such as Rhodamine-B (RhB) dye was investigated by the presence of copper oxide nanowires in aqueous dye solution under sunlight. Typically, in this experimental procedure, 50 mg catalyst was dispersed in 100 ml of 20 ppm aqueous RhB solution at preferred neutral pH and irradiated with sunlight. The powder samples were well dispersed in dye solution by constant stirring, followed by the addition of 5 ml of H2O2 (20 wt %), 4
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
which was used as reaction initiator. H2O2 was additional to enhance the formation of more OH% radicals during photodegradation, ensuing the fast decolouration of dye. The catalyst/RhB solution was kept in the dark region for few hours to attain more adsorption-desorption equilibrium constant of account will loss the dye due to during the surface modification [36]. In the dark condition, RhB molecules were dispersed on the catalyst in the mixture solution. The UV–vis absorption spectrum of the CuO/RhB dispersed solution in the dark after 30 min proves that there is no change in the wavelength at 554 nm, which represents that the RhB model pollutant was not degraded in the dark condition [37]. The catalytic-loaded RhB solution were irradiated under sunlight source at 30 min intervals at air environment was eradicated in the maximum mixture solution to sustain the catalyst well dispersed in the mixture solution. At the certain time intervals, we reveal the 2 ml of photo-reacted centrifuged dye solution from the sunlight illuminated dye solution was with-drawn, were studied by the footage of deviations in the absorption UV band spectrum. The characteristic absorption peak of RhB at 554 nm was selected to monitor the photoinduced degradation and the peak intensity was analysed over a period of 150 min. The disintegration of dye was showed by colour mechanism due to pink in the direction of colourless of the solution [38]. The colour changes of the dye solutions become less concentrated as well as with the intensity of absorption band spectrum will decreasing gradually with increasing the equivalent of irradiation time, hope that indicating the strong oxidation peaks of dye has been arisen in the existence of CuO nanoparticles under sunlight irradiation. At regular intervals, the photo assisted degradation of dye reaction was also carried out in different conditions such as in presence of H2O2, only catalyst and blank [39]. All these explanations which showed that CuO nanowires revealed the excellent performance of RhB degradation dye, the total amount of data have been obtained through the catalytic experiments were taken to calculate the degradation efficiency. The photocatalytic activity of CuO nanowires was estimated by the Ct/C0 ratio vs time Fig. 5(a) for the 0.05 g catalyst /100 ml RhB solution [40]. The higher photocatalytic activity of CuO nanowire can be explained based on the
Fig. 6. Representation of proposed mechanism of degradation of RhB.
different particles shape, the modification on the surface and the particles size. Fig. 5(b) represents the time dependent degradation curves of 20 ppm dye molecule in the presence of photocatalyst / H2O2 is nearly ˜ 95% degrade within 150 min. On the other hand, dye solution with catalyst showed comparatively lesser photocatalytic activity (˜70% degradation in the same time). The blank test without catalytic dye under sunlight irradiation time for 3 h was 1.54% and the percentage of photodegradation dye presence of H2O2 is 3.40%, respectively. As well in Fig. 5(c–d) is the plot of (C/C0) vs time. From our experiment, it is noticeable one to identify the concentration of degradation while increasing with the irradiation time and in the presence of hydrogen peroxide, which means to understand, the UV–vis spectra of RhB dye were demonstrated the photocatalytic progress with entails not only for bleaching of solutions in RhB, it is decomposed, because of the intensity of bandwidth spectrum were assigned the formation of
Fig. 5. (a–d): The experimental data of all the samples can be fitted in a straight line which implies that the dye degradation. The plot of C/C0 (and ln(C/C0)) versus time (t) for degradation of RhB dye using only H2O2 action. 5
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
leads to the generation of HO%radical, finally decompose the dye molecules [47].
aromatic rings in the electronic spectra during the time was decreased as shown in Fig. 6. We note that, the oxidation products of CO2, NO3−, SO42-, H+ and H2O were increasing based on the acidity of the solution. So that, the excellent photocatalytic behaviour of the CuO nanowire is very much attributed to the high specific surface separation involved during the reduction of electron-hole recombination pair of ions, which happen due to the morphology of nanowire-shape textures [41]. So that the, a large specific surface volume ratio is beneficial for absorbing electrons and increasing the unsaturated surface coordination angles to improve the photocatalytic behaviour. In the aspect of absorption, the absorbent capacity of CuO nanowire was obviously stronger [42].
CuO+hv → CuO (e−
CB)
+ (h+
VB)
+ H2O → OH
+
CuO (h
VB)
+
CuO (e−
CB)
+ O2→CuO +.-O2
CuO (h
VB)
%
+
−
OH → %OH
RhB+hν (Sunlight) → RhB* RhB* + CuO →RhB%+ + CuO (e–) RhB + (ROS) (O2%– + h+ + HO%) → mineralized products→CO2 + NO2 + H2O
3.6. Reusability of the catalyst The photocatalyst was distinguished from the solution mixture by centrifugation to identify its stability and reusability nature at the end of the photocatalytic process. At each end of the cycle, the catalyst was removed from the solution mixture by simple filtration, washed thoroughly with pure ethanol and dried at 120 °C the dried sample used for new cycles [43]. Decomposition of dye was repeated for 4 cycles, in each reaction process almost 95% of RhB were degraded within 150 min of sunlight irradiation, which indicates that there is no loss of activity of catalyst. So that the results of all the four-cycle were carried out with catalyst are shown in Fig. 7, from these four cycles represents that there is no loss in photocatalytic nature of the same sample with the fresh dye solution. Thus, the driving trials suggest that the practically applicable to explore the nanostructures system for environmental applications such as active sludge, waste water remediation [44]. Decomposition of synthetic organic RhB dye using CuO nanowire semiconductor on illumination of sunlight initially leads to excitation of the semiconductor. On irradiation of sunlight, higher energy level electrons in the conduction band and holes in the valence band are generated [45]. This photogenerated excitons move to the catalyst surface leads to the chemical reaction. Furthermore, the dyes act as a sensitizer of sunlight goes to excited state and eject excited electrons to semiconductors to become a cationic/anion dye free radical followed by self-degradation or degradation by the reactive oxidation species [46]. A crucial mechanism of photocatalytic reaction is depending on the production of electron-hole pairs. These free electrons and holes alter the surrounding oxygen or water molecule into free ·OH radicals. The highly reactive superoxide radical, transferred across significantly. The photo generated holes (h+) in the valence band react with either H2O or −OH to produce the HO· through the following reactions, While the electrons (e−) in the conduction band react with the adsorbed O2 on the CuO nanowire surface to generate according to the following steps, it
Photocatalytic activity was higher for nanowire due to the obtainability of active surface sites are homogeneity in different adsorption which is characteristically different while the specific surface area is increased, due to the exchange interaction between catalyst and dye molecule were associated can be well-known adsorbent occurred. Likewise, it permits to more surface ions to interact activities among the reactive sites, which belongs to the movement of advanced chemical proficiency to the incident photons. So that the similar effects can be beneficial to establishing the large quantity of active sites for the real interface between catalyst and the dye molecule. However, the UV–vis absorption spectrum, which describes the CuO nanowire are a higher volume absorbance spectrum which deals to confirm the prominent role of interaction between CuO and dye [48]. Foremost, above the results to coordinate which enhance the active surface area which is existing of the catalytic activity is distinguished significantly which enhance the dimension of the matrix has been deducted. Moreover, because of the irrespective nanostructures would be defined a quantum confinement of optically excited carrier’s electrons. So that the QC effect which plays an important role of photo-induced charge degradation effect of organic dyes which may be due to occur the active contribution of quantum confined excitons [49]. Moreover, the quantum confined excitons or optically excited carrier’s ions are not restricted to move over the photocatalysts of CuO nanowire [13,14]. As a result, decreasing crystallite size can also increasing the oxidation potential thereby photoconductivity of the resulted material is enhanced by the narrow bandgap of the CuO nanowires, among the recombination effects of photogenerated electron/ holes lifetime of photogenerated electrons is also prolonged, so that the rod exhibits which higher photocatalytic activity to confirm the our photocatalysis results, among all the reports, not only relates to the surface adsorption ability, but also related to the oxygen defects on the surface area [15–17]. We are noted, that the observed nanowires which enriched the higher catalytic activity to comparing the other neighbouring morphologies [50]. So that the, larger surface volume ratios, are more adsorption rate, which belongings the great charge separation between the electrons/holes in CuO nanowires to established more nanowires are favourable to support above the analysis chart would conclude the stability of active surface area, so that the, catalytic mechanism we expected to confirm the quantum confinement of photoinduced carriers with different morphology, therefore, the photocatalytic activity can be reported in the possibility of ions mechanism which intermediate by-products of RhB were N,N-diethylrhodamine, Nethylrhodamine, 3-hydroxybenzoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid and adipic acid as shown in Fig. 8. Based on these intermediate compounds, to estimate the catalytic degradation pathway of RhB dye were proposed to determine our own views, via two competitive processes; which is (i) N-demethylation and destruction of the conjugated structure and conclude the study that chromophore cleavage, ring opening, and mineralization were the main photocatalytic degradation pathways of RhB dye. (ii) The dye was converted to smaller organic species and ultimately mineralized
Fig. 7. Decomposition of dye was repeated for 4 cycles represents that there is no loss in photocatalytic nature of the same sample with the fresh dye solution. 6
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
Fig. 8. Schematic mechanism of photocatalytic nature of the same sample with the fresh dye solution.
together with other organic groups to inorganic bi-products (e.g., CO2 and water). [10]
4. Conclusion [11]
In summary, all the studies, were shown the copper oxide nanowires which displays a higher volume surface redox activity either or nor the parent single oxides were prepared by the hydrothermal method. So that the degree of compositional heterogeneity pattern of specimen was surface enrichment with Cu ions is ascribable to promote the different relative reports to discuss the precipitation of -O and -Cu atoms. In addition, the CuO nanowire is the surfactant of nature were used to play an important role of reducing agent against the transition phase index from our XRD, HRTEM and micro-Raman results were reported systematically.
[12]
[13]
[14]
[15]
References [16] [1] H.D. Hill, C.A. Mirkin, The bio-barcode assay for the edetection of protein and nucleic acid targets uding DTT-induced ligand exchange, Nat. Protoc. 1 (1) (2006) 324–336. [2] H.D. Hill, R.A. Vega, Nonenzymatic detection of bacterial genomic DNA using the bio bar code assay, Anal. Chem. 79 (23) (2007) 9218–9223. [3] I. Faheem, S. Sammia, A.K. Shakeel, Green synthesis of copper oxide nanoparticles using Abutilon indicum leaf extract: antimicrobial, antioxidant and photocatalytic dye degradation activities, Trop. J. Pharm. Res. 16 (2016) 743–753. [4] S. Yallappa, J. Manjanna, M.A. Sindhe, Microwave assisted rapid synthesis and biological evaluation of stable copper nanoparticles using T. Arjuna bark extract, Spectrochim Acta Mol Biomol Spectrosc. 110 (2013) 108–115. [5] R. Seigneuric, L. Markey, D.S.A. Nuyten, From nanotechnology to nanomedicine: applications to cancer research, Curr. Mol. Med. 10 (2010) 640–652. [6] H. Wang, Q. Pan, J. Zhao, G. Yin, P. Zuo, Fabrication of CuO film with network like architectures through solution-immersion and their application in lithium ion batteries, J. Power Sources 167 (2007) 206. [7] J. Lasek, Y. Yu, J.C.S. Wu, Removal of NOx by photocatalytic processes, J. Photochem. Photobiol. C: Photochem. Rev. 14 (2013) 29. [8] M. Zhu, G. Diao, High catalytic activity of CuO nanorods for oxidation of cyclohexane to 2-cyclohexene-1-one, Catal. Sci. Technol. 2 (2012) 82. [9] S. Sonia, S. Poongodi, P. Suresh Kumar, D. Mangalraj, N. Ponpandian,
[17]
[18] [19] [20]
[21]
[22] [23]
[24]
7
C. Viswanathan, Hydrothermal synthesis of highly stable CuO nanostructures for efficient photocatalytic degradation of organic dyes, Mater. Sci. Semicond. Process. 30 (2015) 585. S.H. Kim, A. Umar, R. Kumar, A.A. Ibrahim, G. Kumar, Facile synthesis and photocatalytic activity of cocoon shaped CuO nanostructures, Mater. Lett. 156 (2015) 138–141. A. Angel Ezhilarasi, J. Judith Vijaya, K. Kaviyarasu, M. Maaza, A. Ayeshamariam, L. John Kennedy, Green synthesis of NiO nanoparticles using Moringa oleifera extract and their biomedical applications: cytotoxicity effect of nanoparticles against HT-29 cancer cells, J. Photochem. Photobiol. B, Biol. 164 (2016) 352–360. K. Kasinathan, J. Kennedy, M. Elayaperumal, M. Henini, M. Malik, Photodegradation of organic pollutants RhB dye using UV simulated sunlight on ceria based TiO2 nanomaterials for antibacterial applications, Sci. Rep. 6 (2016) 38064. M. Kaur, K.P. Muthe, S.K. Despande, S. Choudhury, J.B. Singh, V. Neetika, S.K. Gupta, J.V. Yakhmi, Growth and branching of CuO nanowires by thermal oxidation, J. Cryst. Growth 289 (2006) 670–675. Yi-kun Su, S. Cheng-Min, H. Yang, Hu Li, G. Hong Ju, Controlled synthesis of highly ordered CuO nanowire arrays by template-based sol-gel route, Trans. Nonferrous Met. SOC. China 17 (2007) 783–786. C. Xu, Y. Lin, G. Xu, G. Wang, Preparation and characterization of CuO nanorods by thermal decomposition of CuC2O4 precursor, Mater. Res. Bull. 7 (2002) 2365–2372. J. Moulder, W. Sticke, P. Sobol, K. Bomben, Handbook of X-ray photoelectron spectroscopy, in: J. Chastain (Ed.), Standard ESCA Spectra of the Elements and Line Energy Information, Perkin Elmer Corporation: Physical Electronics Division, USA, 1992. C.D. Wagner, W.M. Riggs, L.E. Davis, J.F. Moulder, G.E. Muilenberg, Handbook of X-ray Photoelectron Spectroscopy Perkin-Elmer Corp. Physical Electronics Division, Eden Prairie, Minnesota, USA, 1979, p. 190. J.C. Irwin, J. Chrzanowski, T. Wei, Raman scattering investigation of Cu18O, Phys. C 166 (1990) 456. J.F. Xu, W. Ji, X. Shen, S.H. Tang, Preparation and characterization of CuO nanocrystals, J. Solid State Chem. 147 (1999) 516–519. C. Shao Liang, C. Ming Feng, Fabrication, characterization, and kinetic study of vertical single-crystalline CuO nanowires on Si substrates, Nanoscale Res. Lett. 7 (1) (2012) 119. Touria Khamliche, Saleh Khamlich, Terry B. Doyle, Daniel Makinde, Malik Maaza, Thermal conductivity enhancement of nano-silver particles dispersed ethylene glycol based nanofluids, Mater. Res. Exp. 05 (2018) 035020. Huaqing Xie, Wei Yu, Yang Li, Lifei Chen Discussion on the thermal conductivity enhancement of nanofluids, Nanoscale Res. Lett. 6 (2011) 124. R. Prasher, P. Bhattacharya, P.E. Phelan, Brownian motion-based convective-conductive model for the effective thermal conductivity of nanofluids ASME, J. Heat Transfer 128 (2005) 588–595. R. Shukla, V.K. Kand Dhir, Effect of brownian motion on thermal conductivity of
Journal of Environmental Chemical Engineering 7 (2019) 103255
N. Kana, et al.
nanofluids ASME J, Heat Transfer. 130 (2008) 042406. [25] T. Itoh, K. Kojima, H. Shimomoto, E. Ihara, Control of lengths and densities of surface-attached chains on polymer particles prepared by dispersion polymerization using macromonomer stabilizer, Polymer 158 (2018) 158–165. [26] M.M. Sabzehmeidani, H. Karimi, M. Ghaedi, Sonophotocatalytic treatment of rhodamine B using visible-light-driven CeO2/Ag2CrO4 composite in a batch mode based on ribbon-like CeO2 nanofibers via electrospinning, Environ. Sci. Pollut. Res. Int. 26 (8) (2019) 8050–8068. [27] K. Kaviyarasu, P.A. Devarajan, A convenient route to synthesize hexagonal pillar shaped ZnO nanoneedles via CTAB surfactant, Adv. Mat. Lett. 4 (7) (2013) 582–585. [28] S.K. Jesudoss, J. Judith Vijaya, P. Iyyappa Rajan, K. Kaviyarasu, M. Sivachidambaram, L. John Kennedy, Hamad A. Al-Lohedan, R. Jothiramalingam, Murugan A. Munusamy, High performance multifunctional green Co3O4 spinel nanoparticles: photodegradation of textile dye effluents, catalytic hydrogenation of nitro-aromatics and antibacterial studies, Photochem. Photobiol. Sci. 16 (5) (2017) 766–778. [29] K. Kaviyarasu, A. Raja, P.A. Devarajan, Structural elucidation and spectral characterizations of Co3O4 nanoflakes, Spectrochim. Acta A. Mol. Biomol. Spectrosc. 114 (2013) 586–591. [30] P. Iyyappa Rajan, J. Judith Vijaya, S.K. Jesudoss, K. Kaviyarasu, L. John Kennedy, R. Jothiramalingam, Hamad A. Al-Lohedan, Mansoor-Ali Vaali-Mohammed, Greenfuel-mediated synthesis of self-assembled NiO nano-sticks for dual applications—photocatalytic activity on Rose Bengal dye and antimicrobial action on bacterial strains, Mater. Res. Express 4 (8) (2017) 085030. [31] Sowmya Sri Rathnakumar, Kana Noluthando, Arockia Jayalatha Kulandaiswamy, John Bosco Balaguru Rayappan, Kaviyarasu Kasinathan, John Kennedy, Malik Maaza, Stalling behaviour of chloride ions: a non-enzymatic electrochemical detection of α-Endosulfan using CuO interface, Sens. Actuators B Chem. 293 (2019) 100–106. [32] D. Saravanakkumar, S. Sivaranjani, K. Kaviyarasu, A. Ayeshamariam, B. Ravikumar, S. Pandiarajan, C. Veeralakshmi, M. Jayachandran, M. Maaza, Synthesis and characterization of ZnO-CuO nanocomposites powder by modified perfume spray pyrolysis method and its antimicrobial investigation, J. Semicond. 39 (3) (2018) 033001. [33] C. Maria Magdalane, K. Kaviyarasu, J. Judith Vijaya, B. Siddhardha, B. Jeyaraj, J. Kennedy, M. Maaza, Evaluation on the heterostructured CeO2/Y2O3 binary metal oxide nanocomposites for UV/Vis light induced photocatalytic degradation of Rhodamine - B dye for textile engineering application, J. Alloys. Compd. 727 (2017) 1324–1337. [34] C.M. Magdalane, K. Kaviyarasu, J.J. Vijaya, B. Siddhardha, B. Jeyaraj, Facile synthesis of heterostructured cerium oxide/yttrium oxide nanocomposite in UV light induced photocatalytic degradation and catalytic reduction: synergistic effect of antimicrobial studies, J. Photochem. Photobiol. B, Biol. 173 (2017) 23–34. [35] K. Anand, K. Kaviyarasu, Sudhakar Muniyasamy, Selvaraj Mohana Roopan, R.M. Gengan, A.A. Chuturgoon, Bio-Synthesis of Silver Nanoparticles Using Agroforestry Residue and Their Catalytic Degradation for Sustainable Waste Management, J. Clust. Sci. 28 (2017) 2279–2291. [36] K. Kasinathan, J. Kennedy, M. Elayaperumal, M. Henini, M. Malik, Photodegradation of organic pollutants RhB dye using UV simulated sunlight on ceria based TiO2 nanomaterials for antibacterial applications, Sci. Rep. 6 (2016) 38064. [37] K. Kaviyarasu, A. Ayeshamariam, E. Manikandan, J. Kennedy, R. Ladchumananandasivam, Uilame Umbelino Gomes, M. Jayachandran, M. Maaza,
[38]
[39]
[40]
[41]
[42]
[43]
[44]
[45]
[46]
[47]
[48]
[49]
[50]
8
Solution processing of CuSe quantum dots: photocatalytic activity under RhB for UV and visible-light solar irradiation, Mater. Sci. Eng. B 210 (2016) 1–9. K. Kaviyarasu, E. Manikandan, J. Kennedy, M. Jayachandran, R. Ladchumananandasiivam, U. Umbelino De Gomes, M. Maaza, Synthesis and characterization studies of NiO nanorods for enhancing solar cell efficiency using photon upconversion materials, Ceram. Int. 42 (7) (2016) 8385–8394. K. Kaviyarasu, C. Maria Magdalane, E. Manikandan, M. Jayachandran, R. Ladchumananandasivam, S. Neelamani, M. Maaza, Well-aligned graphene oxide nanosheets decorated with zinc oxide nanocrystals for high performance photocatalytic application, Int. J. Nanosci. 14 (03) (2015) 1550007. K. Kaviyarasu, C.M. Magdalane, K. Anand, E. Manikandan, M. Maaza, Synthesis and characterization studies of MgO:CuO nanocrystals by wet-chemical method, Spectrochim. Acta A. Mol. Biomol. Spectrosc. 142 (2015) 405–409. K. Kaviyarasu, E. Manikandan, J. Kennedy, M. Maaza, A comparative study on the morphological features of highly ordered MgO: AgO nanocube arrays prepared via a hydrothermal method, RSC Adv. 5 (100) (2015) 82421–82428. K. Kaviyarasu, C. Maria Magdalane, K. Kanimozhi, J. Kennedy, B. Siddhardha, E. Subba Reddy, Naresh Kumar Rotte, Chandra Shekhar Sharma, F.T. Thema, Douglas Letsholathebe, Genene Tessema Mola, M. Maaza, Elucidation of photocatalysis, photoluminescence and antibacterial studies of ZnO thin films by spin coating method, J. Photochem. Photobiol. B, Biol. 173 (2017) 466–475. C. Maria Magdalane, K. Kaviyarasu, J. Judith Vijaya, B. Siddhardha, B. Jeyaraj, Photocatalytic activity of binary metal oxide nanocomposites of CeO2/CdO nanospheres: investigation of optical and antimicrobial activity, J. Photochem. Photobiol. B, Biol. 163 (2016) 77–86. K. Kaviyarasu, L. Kotsedi, A. Simo, X. Fuku, G.T. Mola, J. Kennedy, M. Maaza, Photocatalytic activity of ZrO2 doped lead dioxide nanocomposites: investigation of structural and optical microscopy of RhB organic dye, Appl. Surf. Sci. 421 (2017) 234–239. C. Maria Magdalane, K. Kaviyarasu, J. Judith Vijaya, C. Jayakumar, M. Maaza, B. Jeyaraj, Photocatalytic degradation effect of malachite green and catalytic hydrogenation by UV–illuminated CeO2/CdO multilayered nanoplatelet arrays: investigation of antifungal and antimicrobial activities, J. Photochem. Photobiol. B, Biol. 169 (2017) 110–123. X. Fuku, K. Kaviyarasu, N. Matinise, M. Maaza, Punicalagin green functionalized Cu/Cu2O/ZnO/CuO nanocomposite for potential electrochemical transducer and catalyst, Nanoscale Res. Lett. 11 (1) (2016) 386. S.K. Jesudoss, J. Judith Vijaya, L. John Kennedy, P. Iyyappa Rajan, Hamad A. AlLohedan, R. Jothi Ramalingam, K. Kaviyarasu, M. Bououdina, Studies on the efficient dual performance of Mn1–xNixFe2O4 spinel nanoparticles in photodegradation and antibacterial activity, J. Photochem. Photobiol. B, Biol. 165 (2016) 121–132. X. Fuku, N. Matinise, M. Masikini, K. Kasinathan, M. Maaza, An electrochemically active green synthesized polycrystalline NiO/MgO catalyst: use in photo-catalytic applications, Mater. Res. Bull. 97 (2018) 457–465. A. Raja, S. Ashokkumar, R. Pavithra Marthandam, J. Jayachandiran, Chandra Prasad Khatiwada, K. Kaviyarasu, R. Ganapathi Raman, M. Swaminathan, Ecofriendly preparation of zinc oxide nanoparticles using Tabernaemontana divaricata and its photocatalytic and antimicrobial activity, J. Photochem. Photobiol. B, Biol. 181 (2018) 53–58. Y.S. Reddy, C.M. Magdalane, K. Kaviyarasu, G.T. Mola, J. Kennedy, M. Maaza, Equilibrium and kinetic studies of the adsorption of acid blue 9 and Safranin O from aqueous solutions by MgO decked FLG coated Fuller’s earth, J. Phys. Chem. Solids 123 (2018) 43–51.