Synthesis, characterization and photo-catalytic studies of mixed metal oxides of nano ZnO and SnOx

Materials Science in Semiconductor Processing 51 (2016) 25–32

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Synthesis, characterization and photo-catalytic studies of mixed metal oxides of nano ZnO and SnOx K. Jeyasubramanian a,n, G.S. Hikku a, M. Sivashakthi b a b

Centre for Nanoscience and Technology, Department of Mechanical Engineering, Mepco Schlenk Engineering College, Sivakasi, India Department of Physics, Idhaya College for Women, Sivagangai, India

art ic l e i nf o

a b s t r a c t

Article history: Received 22 January 2016 Received in revised form 31 March 2016 Accepted 28 April 2016

Novel mixed metal oxides of Zinc and Tin (MZOTO) were synthesized by a simple co-precipitation method. The effect of blending varying compositions of SnOx (x ¼1, 2) to ZnO has been evaluated, and it was found that the crystal structure, morphology, optical properties and photo-catalytic behavior were dependent on the percentage of SnOx. The obtained samples were characterized using XRD, EDAX, FESEM, UV–vis spectroscopy, Photoluminescence, etc. XRD data revealed that the ZnO and SnOx co-exist as mixture and their structures were found as hexagonal and cubic/orthorhombic respectively. FESEM image intricate about the morphology of the MZOTO prepared in 1:0.5 ratio providing nano flower structures that resemble like Chrysanthemum species. The band gaps of all the obtained MZOTOs were determined from UV–vis reflectance spectra using Kubelka-Munk relation. Photoluminescence emission studies revealed that the recombination of excited e  with the h þ of ZnO is greatly influenced by SnOx nanoparticles. Visible light photo-catalytic activities of MZOTOs were followed spectrophotometrically against the degradation of crystal violet solution. MZOTO2 obtained in the ratio of 1:0.5 shows better catalytic efficiency compared to other samples, degrading crystal violet completely within 40 min. The reusability and free radical trapping experiments were performed to study the performance and mechanism of MZOTO2 as the photo-catalyst. The photo catalytic efficiency of 1:0.5 MZOTO was higher due to the presence of flower-like structures that effectively captivated more photons from the sunlight. & 2016 Elsevier Ltd. All rights reserved.

Keywords: Mixed metal oxides Nano flower Band gap Photo-catalyst Photo-degradation Free radicals trapping experiment

1. Introduction All over the world, the current concern of debate is to degrade the industrial pollutants that are dumped into the fresh/sea water [1]. The industrial sewage comprises of toxic organic complexes which eventually causes many environmental issues [2,3]. Dye industry plays a major role in polluting the fresh water eco-system that discharges about 15% of dyes into the environment during synthesis and processing [4–6]. The conventional methods adopted to eradicate the organic pollutants from the polluted water are flocculation, absorption, reverse osmosis, biodegradation, etc. These methods either transfer the chemicals to solid state or produce large slurries which in turn cause secondary pollution. All such draw backs could be overcome by the photo-catalytic degradation technique that promotes eco-friendly tactics, where the organic pollutants are disintegrated into smaller non-toxic molecules by UV & visible light exposure in presence of suitable catalyst. Obviously, semiconductor nano particles are being considered n

Corresponding author. E-mail address: [email protected] (K. Jeyasubramanian).

http://dx.doi.org/10.1016/j.mssp.2016.04.017 1369-8001/& 2016 Elsevier Ltd. All rights reserved.

as an efficient candidate for the photo-catalytic degradation process since it possess high surface to volume ratio which greatly influences the number of active sites thereby accelerating degradation process [7]. Typical photo-catalysts extensively studied in the photo-degradation processes are zinc oxide, tin oxide, titanium oxide, etc. in its pure form [8–11]. Zinc oxide and Tin oxide are semiconductor metal oxide materials which have broad range of applications such as photo-degradation, optoelectronic devices, gas sensors, etc., due to their distinctive size and shape dependent characteristics [12]. Individually, the semiconducting particles like zinc oxide and tin oxide shows lower catalytic efficiency against the degradation of organic pollutants owing to the immediate recombination of electron–hole (e  /h þ ) pair generated under UV–vis light exposure [13–15]. Moreover, the photo-catalytic activity of semiconducting materials can be further enhanced by blending with suitable additives that give hetero-structured arrangement which can facilitate the electronic properties thereby delaying e  /h þ pair recombination process [16,17]. Apart from these, the physical and chemical properties of the mixed oxides vary from the individual components due to the existence of many phases [18]. Rather than

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using pure ZnO as photo-catalyst for degradation of organic pollutant, SnOx is chosen as an additive which may inhibits the instant recombination of e  /h þ pair during UV–vis light exposure. Such a delayed recombination of e  /h þ pair is vital for the decomposition of organic pollutants that will be achieved by mixing ZnO and SnOx in varying composition. This work details about the isolation of mixed metal oxides of zinc oxide with varying quantities of tin oxide (MZOTO) by chemical route and their structure, morphology, optical properties and photo catalytic activities has been studied extensively. Photocatalytic activities of mixed metal oxides have been found more efficient than pure ZnO for degrading crystal violet (CV) on exposing to sunlight.

2. Materials and methods 2.1. Synthesis of ZnO nanoparticles All the chemicals used in this work were of analytical grade, used without further purification. 0.05 M sodium hydroxide solution was added drop by drop to the 0.01 M zinc acetate solution with continuous stirring at room temperature. A white precipitate was visualized due to the formation of Zn(OH)2. The obtained precipitate was separated by filtration, washed with deionized water and dried at 120 °C for 5 h. The dried powder was calcinated at 700 °C for 1 h in a muffle furnace which yield ZnO nanoparticles and was stored in vacuum. 2.2. Synthesis of MZOTO mixed metal oxides 50 ml separate solutions comprising 0.0025, 0.005, 0.0075 and 0.01 M tin (II) chloride dissolved in distilled water were mixed individually with 50 ml 0.01 M zinc acetate solution at room temperature. To this, 50 ml solution containing 0.05 M NaOH was added drop wise with vigorous stirring. The resultant samples were named as MZOTO1, MZOTO2, MZOTO3 and MZOTO4 respectively, collectively referred as MZOTOs. The above mixture was stirred till a white precipitate was formed. The obtained precipitate was filtered and washed many times with deionized water followed by ethanol several times to remove the excessive ions. The precipitate was dried at 120 °C for 5 h, and it was calcinated at 700 °C in a muffle furnace for 1 h and was stored in vacuum. Flow chart describing the process involved in the isolation of mixed metal oxides is given in Fig. 1.

(for getting evenly distributed nano particles in the CV solution) and the mixture was exposed to sunlight. Periodically, once in 5 min the contents present in the reaction mixture exposed to sunlight were drawn and the change in absorbance of the solution was followed spectroscopically (Pekin Elmer, Lambda 25, USA) using UV–vis spectrometer at λmax ¼579 nm. Since CV shows its characteristic absorption at 579 nm, the spectrophotometry was followed at that specific wavelength.

3. Results and discussion 3.1. XRD characterization of MZOTOs The phase and structural investigation of MZOTOs were done from the powder XRD pattern recorded in the range of 2θ ¼10° to 80° using Siefert X-ray diffractometer. Different sets of diffraction peaks were visualized from the XRD pattern of MZOTOs. The diffraction peaks observed at 2θ ¼31.8°, 34.4°, 36.2°, 47.5°, 56.6°, 62.9°, 66.4°, 67.9°, and 69.06° corresponds to the hexagonal ZnO structure resembled the JCPDS file no. 89-1397 [19]. The diffraction peaks corresponding to 2θ ¼ 31.8°, 36.2°, 39.42° and 51.09° are attributed to the cubic structure of SnO2 matched with the JCPDS No. 33-1374 [20]. Besides, low intensity diffraction peaks found at 2θ ¼16.2°, 32.9°, 45.46° and 58.03° are attributable to SnO that exist along with SnO2 nano particles in trace amount having orthorhombic phase corresponding to the JCPDS No. 77-2296. The XRD patterns of all the mixed oxides are depicted in Fig. 2. The crystalline nature of ZnO nanoparticles can be inferred from the XRD pattern showing sharp peaks. While on increasing the molar concentration of SnOx, the diffraction peak becomes broadened and the peak sharpness gets reduced. Apart from the peak sharpness, another noteworthy feature was noticed while looking the XRD of MZOTOs from MZOTO1 to MZOTO4. The characteristic peaks of ZnO at 2θ ¼31.7° and 36.2° (from JCPDS file No. 89-1397) are very close to the major reflections of SnO2 found at 2θ ¼ 31.5° and 36.4° (from JCPDS file No. 33-1374) respectively. So, in the mixed state, the peaks are merged together and appeared as a single peak with higher intensity. Also, from the XRD data it is noticed that when the molar concentration of SnO2 increases, the preferential orientation peak at 2θ ¼31.8° increases gradually. The increase in composition of tin oxide also modifies the crystalline nature of MZOTOs into amorphous type, which is further visualized from FESEM images given in Section 3.2. 3.2. FESEM and EDAX analysis

2.3. Photo catalytic studies Photo catalytic degradation studies of CV was examined by mixing 0.1 g of MZOTO powder in 100 ml of water containing 1 mg of CV. The contents were then sonicated using SONICS, 750 W, USA

The morphology of ZnO and MZOTOs were analyzed from the FESEM micrograph obtained using Carl Zeiss, Neon 40, is represented in Fig. 3(a, c, e, g, i). From Fig. 3(a), the morphology of ZnO was visualized as near spherical shaped particles of size ranges from 150 to

Fig. 1. Flow chart for the synthesis of MZOTO mixed metal oxide.

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where F (R1) is usually termed as re-emission or K-M function. K is absorption co-efficient and S is the Scattering co-efficient. Typically, the band gap values were determined based on a plot drawn between (F(R) hν)2 vs hν. By extrapolating the linear portion of the curve to (F(R) hν)2 ¼ 0 gives the optical band gap value of the MZOTOs. Band gap evaluated for ZnO, MZOTO1, MZOTO2, MZOTO3, and MZOTO4 are 3.27 eV, 3.2 eV, 3.18 eV, 3.15 eV and 3.14 eV respectively. In fact, from the determined band gap values, it is clear that all the MZOTOs band gap values are faintly vary from pure ZnO. Such a reduction in band gap noticed in MZOTOs is ascribed to the band shrinkage effect due to the attachment of SnOx on the surface of ZnO nanoparticles. This fact shows the increase in electron cloud in the conduction band during irradiation. Further, the anchoring of SnOx nanoparticles at ZnO surface helps to enhance the visible light catalytic property to MZOTO structures [23]. The prepared MZOTOs are likely to display improved photocatalytic activity, since more electrons in the conduction band results in faster degradation of pollutants. Fig. 2. XRD patterns of MZOTOs.

3.4. Photoluminescence (PL) studies

200 nm. The crystalline nature of the ZnO was also evidenced from the XRD results. However, while adding SnOx into ZnO, the crystalline nature of ZnO declined gradually and turned into amorphous characteristics [Fig. 3(c, e, g, i)]. FESEM images of MZOTO samples further support the fact that the increase in composition of SnOx alters the crystallinity of ZnO into amorphous nature. The same fact was also supported by the XRD results. More interestingly, the sample MZOTO2 displays flower-like pattern with nano dimensions resembling that of Chrysanthemum species is shown in Fig. 3(e). These flower-like structures entangle more energy from the sunlight within its petals and enhance the photo catalytic reaction by exciting more electrons [21]. The elemental composition of ZnO and MZOTOs are supported by the data obtained from the EDAX analysis is shown in Fig. 3(b, d, f, h, j). Fig. 3(b) exhibits peaks attributable to Zn and O atoms further confirm the presence of ZnO. While the EDAX results originated from MZOTOs shown in Fig. 3(d, f, h, j) additionally exhibits peak corresponding to Sn atoms with simultaneous increase in oxygen atoms. All these facts support the fact that the as obtained powders are mixed metal oxides originating from both ZnO and SnOx. 3.3. Optical diffuse reflectance spectral analysis of ZnO and MZOTOs The reflectance spectra of MZOTOs recorded using UV–vis spectrophotometer, Shimadzu, UV-2450, Japan are shown in Fig. 4. ZnO and their mixed oxides exhibit a sharp absorption edge in the UV region. The absorption peak found in the reflectance spectra of ZnO and MZOTOs depend on the excitation energy of the valence electrons of ZnO and SnOx. While on adding nano SnOx to pure ZnO, the absorption edge slightly shifted towards higher wavelength i.e. lower energy. This change in absorption edge is attributable to the interaction of ZnO nanoparticles with nano SnOx. Therefore, with the addition of SnOx, the energy required to excite the valence electrons to conduction band is lower compared to ZnO alone and thus facilitating more excited electrons for the MZOTOs than pure ZnO enhancing the photocatalytic activity. The band gaps of as-obtained samples were calculated using the absorption edge values obtained from the reflectance spectra and interpreted using Kubelka-Munk formula [22]. The band gap energy is evaluated using the expression given below,

F (R ∞) =

(1 − R ∞)2 K = 2R ∞ S

where R∞ = Rsample /Rstandard

(1)

PL study is a useful tool to investigate the nature of photogenerated e  /h þ pairs in semiconducting materials. Since PL emission originates from the radiative recombination of excited electrons with the valence band holes. Sharp and strong intensity emission results from quicker recombination process whereas lower recombination process reflected with weaker PL intensities [24]. The PL spectra of ZnO and MZOTOs were recorded using Spectrofluorophotometer, Shimadzu, RF-5301pc, Japan, in the range of 300–900 nm with an excitation wavelength of 280 nm is shown in Fig. 5(a and b). The PL spectrum of the ZnO [Fig. 5(a)] shows peaks at 383 nm, 416 nm, 441 nm, 463 nm, 490 nm, 540 nm, 569 nm, and 800 nm. The peak at 383 nm in the UV region is attributed to the near band-edge emission. The blue emission found at 416 nm, 441 nm, and 463 nm are assigned to the phenomenon like defects in interstitials, vacancies, etc. [25–28]. The high intensity peak at 540 nm is ascribed to the recombination of photo generated holes with surface defects [29]. The peak at the red band (800 nm) is attributable to the electronic transition phenomenon facilitated by defects. PL spectra of the mixed metal oxides are shown in Fig. 5(b), which displays variation in their emission intensities with the increase in the percentage of SnOx. All mixed metal oxides exhibit the same peak position but slightly vary with emission intensities. Especially, the MZOTO2 exhibit a band corresponding to 490 nm with lesser intensity. This variation in intensity is attributable to the fact that the SnOx inhibits the recombination rate of e  /h þ pairs generated during exposure to photo-excitation. 3.5. Photo catalytic activity Crystal violet has been taken as the synthetic test pollutant to examine the photo-catalytic efficiency of prepared ZnO and the MZOTOs to be degraded under sunlight. While photons incident on the catalysts, photon absorption, charge carrier creation, surface energy trapping, etc. takes place instantaneously. Followed by these processes, active free radicals are generated that interacts with the carbonaceous network of dye molecules and mitigates completely [30]. By photo-irradiation, the valence band electrons exist on the catalysts get excited and generates e  /h þ pair. The holes in the valence band react with the hydroxyl group of the water molecules promotes the formation of hydroxyl radicals (OH) and the electrons in the conduction band interacts with the dissolved oxygen which in turn induces the formation of super oxide anions (O2  ). These hydroxyl radicals and super oxide anions O2  further reacts with the photo-excited CV and degrade it

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Fig. 3. FESEM images (a, c, e, g, i) and EDAX spectra (b, d, f, h, j) of ZnO, MZOTO1, MZOTO2, MZOTO3, and MZOTO4.

into smaller fragments. Such a photo-degradation process can be obviously takes place owing to the separation of e  /h þ pairs promoted by adding tin oxide as supplementary with zinc oxide. Experimentally, the photo-degradation process was followed by exposing CV solution in water medium in presence of mixed metal oxides of zinc oxide and tin oxide. In the beginning, the dye looks dark violet in color indicating higher concentration. As the degradation process occurs, the color of the dye fades to light

violet and finally becomes colorless which obviously confirms the decrease in concentration. In presence of MZOTOs, the CV solution undergoes effective decolourization owing to the superior photocatalytic activity that originates from the effective charge separation process influenced by SnOx and ZnO. The UV–visible absorption spectra of the CV at different time intervals of exposure to sunlight in the presence of photo-catalyst are given in Fig. 6(a). It is to be noted that the absorbance at λmax

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heterogeneous system. The photo degradation process exhibits first-order-kinetics at lower concentration, which is represented in simplified form as,

Fig. 4. Reflectance spectra of the ZnO and MZOTOs.

(579 nm) reduces with increase in exposure time indicating the reduction in dye concentration [31]. The intensity of the absorption band decreases rapidly on exposure to sun light irradiation and almost disappeared after 40 min of exposure along with MZOTO2 as photo catalyst, which was found to be quicker than pure ZnO and other MZOTO samples (180 min for pure ZnO, 160 min for MZOTO1, 75 min for MZOTO3 and 95 min for MZOTO4). The higher performances of MZOTOs than pure ZnO is due to the existence of both the spiky structures and the hetero-junctions. The extra-ordinary performance of the MZOTO2 is attributable to the nano-flower like hierarchy that effectively interacts with more photons while on exposure to sunlight by multiplereflection. Further, these facts are also substantiated from the photoluminescence emission studies conducted for MZOTOs. In particular, MZOTO2 revealed a low intensity peak at λ ¼490 nm in comparison with other samples. The lower recombination rate of e  /h þ pair admits the participation of excited electrons in the degradation process. Therefore, the electrons from the ZnO are in the excited state for a longer period and forms electron cloud in the conduction band resulting efficient photo catalytic behavior. Fig. 6(b) shows the optical density of CV at λmax ¼ 579 nm versus the time of exposure kept in sunlight. The plot evidently explains about the increase in exposure time reduces the optical density of CV. The plot clearly revealed about complete degradation of CV using MZOTO2 after exposing to sun light for 40 min. However, all other samples exhibits declined rate of degradation compared to MZOTO2. The Langmuir–Hinshelwood relation can be used to describe the steady state photo catalytic reaction of ZnO/SnOx

dC /dt =−KcC

(2)

⎛C ⎞ ln⎜ 0 ⎟ = Kct ⎝ Ct ⎠

(3)

where Kc is the rate constant of the degradation process, C0 is the initial concentration of the dye and Ct is the concentration of dye after exposing to sunlight at time t. To find the rate constant of the degradation process, a plot was drawn with ln(C0/Ct) vs the degradation time for all the samples [Fig. 6(c)]. The linear fit for each graph was drawn from the resultant equation, the slope gives the rate constant, Kc. Based on the first order kinetic equation, the evaluated rate constant values are tabulated in Table 1. The Kc values were assessed from the slope of the equation and the values are 0.00913, 0.01063, 0.10168, 0.02735, and 0.02373 min  1 for ZnO, MZOTO1, MZOTO2, MZOTO3, and MZOTO4 respectively. From the Kc values, it is understand that the MZOTO2 shows a higher rate of reaction compared to other samples resulting in exceptional photo catalytic degradation process. The estimated values of Kc and the corresponding complete degradation time for all the samples are depicted in Fig. 6(d). As the SnOx is added above the critical value, the spiky structures starts to fade and the hetero-junctions are reduced due to the free standing SnOx. These phenomenons reduce the efficiency of the catalyst to degrade CV. Therefore, the optimum amount of SnOx leads to the formation of nano flowers with enhanced photo catalytic efficiency is found to be 1:0.5 M of ZnO and SnOx designated as MZOTO2. 3.5.1. Free radicals trapping experiments Free radical trapping experiments were performed to gain some insight about the role of active species in the degradation of CV by MZOTO2. While adding isopropyl alcohol (quencher of hydroxyl radicals [32]) during photo-catalytic degradation of CV by MZOTO2, the degradation process was not inhibited. This indicates that the hydroxyl radical was not a primary reactive species responsible for the degradation of crystal violet. However, to investigate the role of active oxygen species, benzoquinone was added as an O2  scavenger [33]. The obtained results displays that there is a considerable change in the rate of reaction by inhibiting the degradation of CV and hence it is obvious that the O2  takes part in the photo-degradation of CV by MZOTO2. Also, to study the importance of h þ in the degradation process, di-sodium salt of

Fig. 5. (a) PL spectra of nano ZnO and (b) PL spectra of MZOTO mixed metal oxides.

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Fig. 6. (a) Photo-catalytic degradation of CV using MZOTO2 (b) absorption vs irradiation time graph for the photo degradation of CV using ZnO and MZOTOs (c) ln(C0/Ct) vs irradiation time for the photo degradation of CV using ZnO and MZOTOs (d) rate constant and degradation time as a function of SnOx.

Table 1 Linear kinetic equation, rate constant, and degradation time for different samples. Sample

First order kinetic equation

Kc (min  1) Complete degradation time (min)

ZnO

ln(C0/Ct) ¼ 0.00913x  0.0116 ln(C0/Ct) ¼ 0.01063x  0.00691 ln(C0/Ct) ¼ 0.10168x  0.42843 ln(C0/Ct) ¼ 0.02735x 0.02735 ln(C0/Ct) ¼ 0.02373x  0.04692

0.00913

180

0.01063

160

0.10168

40

0.02735

75

0.02373

95

MZOTO1 MZOTO2 MZOTO3 MZOTO4

Fig. 7. Comparison of photocatalytic degradation of crystal violet by MZOTO2 in presence of iso-propyl alcohol, benzoquinone and EDTA-2Na.

EDTA is added as a quencher [34] and observed that the degradation process was greatly inhibited. These facts [Fig. 7] indicates that the O2  and h þ are the primary active species that took part in the degradation of CV and not OH radicals. 3.5.2. Stability and reusability analysis For practical application of MZOTO2 to be used as a photocatalyst for the degradation of organic pollutants, the reusability/ stability of the material was analyzed [35,36]. It was checked by separating the MZOTO2 particles by centrifugation after each and every cycle, washed with distilled water and dried at 105 °C. Photo-catalytic ability of the recycled MZOTO2 was evaluated in the same manner detailed in Section 2.3. The aforementioned process was repeated for 5 cycles and the results show efficient mineralization of dye with only 3.2% decrease in the degradation efficiency [Fig. 8]. 3.5.3. Mechanism of crystal violet degradation by MZOTO2 The prime active species normally takes part in the photo-degradation of dye includes e  /h þ pair, hydroxyl radical OH, superoxide radical O2  , singlet oxygen species, etc. [37]. Among these reactive species, photon induced holes, OH and O2  are the prominent constituents that are responsible for the complete degradation of dye by photo-degradation [38]. However, the free radical trapping experiments shows that only O2  and photon induced holes have took part in the photo-degradation of CV by MZOTO2. The role of OH is negligible when compared to the reactivity of O2  . In addition, dye-sensitized degradation process also takes place while exposing to UV–vis light. On exposing the CV solution to sunlight, the electrons in the valence band of dye gets excited, moving towards the conduction band of ZnO. The electrons excited from the ground level of ZnO to the conduction band [Ec (ZnO) ¼ 

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Acknowledgement The authors are very grateful to the Management and the Principal of Mepco Schlenk Engineering College, Sivakasi, for their constant encouragement and support extended to perform this work. Mr. G. S. Hikku expresses his sincere gratitude to the Department of Space, Indian Space Research Organisation (ISRO), India (Grant no. ISRO/RES/3/656) for providing financial support.

Appendix A. Supplementary material Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.mssp.2016.04.017. Fig. 8. Recycling efficiency of MZOTO2 for degrading crystal violet.

References

Fig. 9. Photo degradation by possible charge separation processes.

4.155 eV] was not combined immediately with the hole, instead it relocates its position to the conduction band of SnO2 since it is having lower band energy [Ec (SnO2)¼  4.5 eV] and subsequently takes part in the photo-chemical reaction to produce reactive oxygen species. Therefore, the photo-catalytic and photo-sensitized process occurs concurrently and continuously which generate reactive species, in turn reduces/degrades the CV, which is graphically depicted in Fig. 9.

4. Conclusion ZnO nanoparticle and mixed MZOTOs with four different molar ratios were isolated employing simple precipitation technique. XRD result confirmed the presence of ZnO and SnOx nano crystallites in the mixed oxides state. The band gaps of all the samples were determined using Kubelka-Munk function from diffuse reflectance spectra. The photoluminescence studies confirmed the reduction in recombination rate of the MZOTOs. The photo-catalytic activity of ZnO was drastically increased with the increase in SnOx molar ratio. Especially, MZOTO2 degrades the CV in 40 min. Other than MZOTO2, all the samples took longer time of exposure for deactivating the organic pollutant. This reduction in degradation efficiency was attributable to the excess amount of SnOx, that suppressed the number of hetero-junctions and increased the free standing SnOx particles which possess poor photo catalytic activity. Based on these, we optimized the composition of mixed oxides in the ratio of 1:0.5 that deactivate the synthetic pollutant to a greater extent. This study offers some insight into the future development of technological applications related to the degradation of industrial dyes.

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