Shape control and selective decoration of Zn2SnO4 nanostructures on 1D nanowires: Boosting chemical–sensing performances

Sensors & Actuators: B. Chemical 290 (2019) 210–216

Contents lists available at ScienceDirect

Sensors and Actuators B: Chemical journal homepage: www.elsevier.com/locate/snb

Shape control and selective decoration of Zn2SnO4 nanostructures on 1D nanowires: Boosting chemical–sensing performances Tingting Zhou, Xiupeng Liu, Rui Zhang, Yubing Wang, Tong Zhang

T

⁎

State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, PR China

A R T I C LE I N FO

A B S T R A C T

Keywords: 1D nanostructure Zn2SnO4 subunits Controllable morphology Heterostructure Chemical sensors

One–dimensional (1D) heterostructures are promising for the fascinating physical/chemical properties. However, the selective deposition of innovative materials as efficient active sites on the backbone material is still challenging and meaningful. Herein, a universal strategy is presented to synthesize the novel 1D heterostructure, which is constituted of Mn3O4 nanowires (Mn3O4 NWs) and nano–sized Zn2SnO4 subunits with controllable morphologies including Zn2SnO4 nanorods (Zn2SnO4 NRs), Zn2SnO4 nanocubes (Zn2SnO4 NCs) and Zn2SnO4 nanooctahedrons (Zn2SnO4 NOs). The 1D Mn3O4/Zn2SnO4 heterostructure is proved to generate abundant surface adsorbed oxygen molecules to modulate the sensing activity in chemical sensors (CSs) for application in the acetone vapor detection. The developed gas sensor shows enhanced responses, ultrafast response time and great stability. The selective deposition method and interface engineering will open up an avenue to design the heterostructured nanomaterials for high–performance CSs and other potential applications.

1. Introduction The realization of high–performance sensing materials is of great significance and has been regarded as one of the great scientific challenges for recent years. Particularly, there is a growing demand for gas sensing devices that are high–sensitive, selective, low–cost and environmentally friendly in regard of monitoring air quality and human health [1–3]. To date, many binary metal oxide semiconductors (MOSs), such as ZnO, SnO2, Co3O4, CuO and Mn3O4, have been extensively reported as gas sensing layers [4–9]. However, the sensing ability of binary MOSs is always limited because of the simple component and intrinsic property [10]. Heterostructure constructing and interface engineering provide an effective way to overcome the bottleneck via the growth of a second material on the backbone and integrating the merits of various components into one entity [11]. In addition, ternary MOSs, which involve tunable chemical composition, synergistic effects and rich defects can be considered as potential materials to decorate binary MOSs. To accomplish this, the design and construction of heterostructured sensing materials is very important to improve the sensing performances. One–dimensional (1D) heterostructures with complex oxide interfaces offer new possibilities for the sensing layers of CSs. The sensing properties can be tailored by the structural units loaded on the backbone. Deng et al. has reported that TiO2 nanofibers functionalized with

⁎

catalytic CuO nanocubes showed a higher response to formaldehyde than the pure TiO2 nanofibers and CuO nanocubes [12]. Na et al. engineered the Mn3O4–decorated ZnO nanobelts, which proved that the response and selectivity could be enhanced by the configuration of p–n junction in heterostructures [13]. Despite the above advances, the fabrication of properly engineered 1D heterostructures with well–defined interfaces and morphologies is still challenging and highly desirable for the study and realization of gas sensing optimization. To the best of our understanding, to enhance gas sensing performances for 1D heterostructures by controlling the shape of Zn2SnO4 and creating more adsorbed oxygen molecules has never been investigated before. Thus, considering the modulation of compositions and structures, herein, Mn3O4 NWs functionalized with various Zn2SnO4 nanomaterials in the shape of rod/cube/octahedron–like were successfully fabricated under the hydrothermal condition. The gas sensors, which are made of the 1D heterostructured materials with different hetero interfaces showed the excellent acetone sensing performances. The response of Zn2SnO4 NOs loaded on Mn3O4 NWs–based sensor was significantly higher than that of the others (cube and rod–like Zn2SnO4).

Corresponding author. E-mail address: [email protected] (T. Zhang).

https://doi.org/10.1016/j.snb.2019.03.048 Received 3 November 2018; Received in revised form 21 January 2019; Accepted 9 March 2019 Available online 22 March 2019 0925-4005/ © 2019 Published by Elsevier B.V.

Sensors & Actuators: B. Chemical 290 (2019) 210–216

T. Zhou, et al.

Fig. 1. Illustration of the formation of Mn3O4 NWs, NW-NRs, NW-NCs and NW-NOs.

2. Experimental

mixture was transferred into a Teflon–lined autoclave (50 mL) and reacted at 180 °C for 9 h. The precipitate was centrifuged and collected with distilled water and ethanol three times. NW–NRs were obtained by annealing the precursor at 350 °C for 2 h.

2.1. Materials Polyvinylpyrrolidon (PVP), hexadecyl trimethyl ammonium bromide (CTAB), sodium stannate trihydrate (Na2SnO3•3H2O), tin chloride pentahydrate (SnCl4•5H2O), potassium permanganate (KMnO4), ammonia solution (NH3•H2O), sodiun hydroxide (NaOH), zinc acetate dihydrate (Zn(CH3COO)2•2H2O) and zinc sulfate heptahydrate (ZnSO4•7H2O) were all purchased from Shanghai Chemical Corp.

2.2.3. Synthesis of Mn3O4 NWs decorated with Zn2SnO4 NCs (NW–NCs) γ–MnOOH nanowires (0.08 g) were successively dispersed in H2O (5 mL) with ultrasonic treatment. After that, a mixed solvent consisting of Zn(CH3COO)2•2H2O (0.2 M, 1 mL) and Na2SnO3•3H2O (0.18 M, 1mL) was added into the above solution. Then, NH3•H2O (8 mL) was dropped slowly in the solution with continuously stirring. The obtained mixture was transferred into a Teflon–lined autoclave (50 mL) and reacted at 180 °C for 9 h. The precipitate was centrifuged and collected with distilled water and ethanol three times. NW–NCs were obtained by annealing the precursor at 350 °C for 2 h.

2.2. Synthesis process 2.2.1. Synthesis of Mn3O4 NWs Mn3O4 NWs were prepared by the hydrothermal method that our group reported before [14]. KMnO4 (0.19 g) and PVP (0.1 g) were well–dispersed in H2O (80 mL). After stirring for 20 min, the mixed solution was heated for 9 h at 180 °C under hydrothermal condition. The obtained samples (γ–MnOOH nanowires) were washed and harvested by centrifugation using ethanol and deionized water. Then, Mn3O4 NWs were prepared by annealing at 350 °C for 2 h in air.

2.2.4. Synthesis of Mn3O4 NWs decorated with Zn2SnO4 NOs (NW–NOs) γ–MnOOH nanowires (0.08 g) were successively dispersed in H2O (25 mL) with ultrasonic treatment. A mixed solvent (10 mL) consisting of ZnSO4•7H2O (0.2 mmol), SnCl4•5H2O (0.1 mmol), CTAB (0.02 g) and NaOH (1.5 mmoL) was added into the above solution with continuously stirring. The obtained mixture was transferred into a Teflon–lined autoclave (50 mL) and reacted at 200 °C for 24 h. The precipitate was centrifuged and collected with distilled water and ethanol three times. NW–NOs were obtained by annealing the precursor at 350 °C for 2 h.

2.2.2. Synthesis of Mn3O4 NWs decorated with Zn2SnO4 NRs (NW–NRs) γ–MnOOH nanowires (0.08 g) were successively dispersed in H2O (5 mL) with ultrasonic treatment. After that, a mixed solvent consisting of Zn(CH3COO)2•2H2O (0.2 M, 7 mL) and Na2SnO3•3H2O (0.18 M, 7 mL) was added into the above solution. Then, NH3•H2O (8 mL) was dropped slowly in the solution with continuously stirring. The obtained 211

Sensors & Actuators: B. Chemical 290 (2019) 210–216

T. Zhou, et al.

towards each other to form a branch–like structures (Fig. 3b). Fig. 3c shows a typical schematic diagram of NW–NRs. In order to investigate the Zn2SnO4/Mn3O4 heterostructure in more details, TEM was further employed and the images are shown in Fig. 3d. Fig. 3e–h presents EDX (energy-dispersive x-ray) element mapping images of Mn, Zn, Sn and O, indicating the uniform element distribution for NW–NRs. Fig. 3i–j presents the typical morphological characterizations of the heterostructure of NW–NCs. These cube–shaped Zn2SnO4 with an average diameter of 100 nm anchored randomly on the Mn3O4 backbone without serious agglomeration. The TEM image of an individual 1D structure is shown in Fig. 3l, which shows that secondary Zn2SnO4 has clear cube structure. The elemental mapping analysis of the Zn2SnO4/ Mn3O4 materials suggests the different dispersion and existence of Mn, Zn, Sn and O elements (Fig. 3m–p) in the entire heterostructure. Fig. 3q–r shows the SEM images of NW–NOs, which consist of Mn3O4 NWs assembled by Zn2SnO4 NOs. The TEM and elemental mapping results also demonstrate the close connection between Zn2SnO4 NOs and Mn3O4 NWs (Fig. 3s–x). The corresponding HRTEM (high resolution transmission electron microscope) images of Mn3O4 NWs and Zn2SnO4 of NW–NRs, NW–NCs and NW–NOs are shown in the Fig. 4, respectively. The interplanar distance of 0.23 nm was indexed to the (400) plane of Mn3O4 NWs (Fig. 4a). Fig. 4b shows the HRTEM images of Zn2SnO4 NRs in Mn3O4/ Zn2SnO4 heterostructure. The well–defined lattice fringes can be observed obviously with the interplanar distance of 0.26 nm, which can be indexed to the (311) crystalline plane of the Zn2SnO4 phase. However, there is no clear lattice fringe in Fig. 4c for Zn2SnO4 NCs, further indicating the cube–shaped Zn2SnO4 on the surface of Mn3O4 NWs is amorphous phases. The result is in a good agreement with the XRD analysis. The HRTEM image collected from the Zn2SnO4 NOs in Mn3O4/ Zn2SnO4 heterostructure exhibits the lattice spacing value of 0.31 nm, which is close to the distance of the (220) facet of Zn2SnO4 (Fig. 4d). The XPS spectrum of the heterostructure was carried out to investigate the chemical compositions and valence state, as shown in Fig. 4e–j. The Zn 2p spectrum (Fig. 4e) presents two peaks located at ≈1021.4 and ≈1044.5 eV, which correspond to Zn 2p3/2 and 2p1/2 levels, respectively [17,18]. In the Sn 3d spectrum (Fig. 4f), two peaks centered at ≈ 486.8 and ≈ 495.3 eV are attributed to Sn3d5/2 and Sn3d3/2 [9]. The Mn 2p spectra (Fig. 4g) exhibited two peaks at 641.9 and 653.7 eV associated with Mn 2p3/2 and Mn 2p1/2 [19,20]. Fig. 4h–j shows the O 1s peaks of NW–NRs, NW–NCs and NW–NOs, suggesting the significant differences of oxygen states in Mn3O4/Zn2SnO4 heterostructures. The O 1s peaks were resolved into three centered Gaussian components that can be seen at ≈ 530 eV (OL), ≈ 531 (OV), and ≈ 532 eV (OC), respectively. The OL component located at 530 eV can be attributed to the lattice oxygen. The peak OV with binding energies of 531 eV is associated with oxygen–deficiency. The OC component (532 eV) is usually ascribed to adsorbed oxygen species (O2−, O2−, O−) and hydroxyl (OH−) [21–23].

2.3. Characterization The phase structures of different calcined products were investigated by a X–ray diffraction (XRD, Rigaku D/Max–2550 diffractometer, Cu Kalpha radiation, λ =1.5403 Å). The field emission scanning electron microscope (FESEM, JEOL JSM–7500 F) and transmission electron microscopy (TEM, JEOL JEM–2100 F) were carried out to observe the microstructures and morphology of the samples. The chemical states were recorded by the X–ray photoelectron spectrograph (XPS, ESCALAB MKK II). Pore volumes and specific surface area of Mn3O4/Zn2SnO4 heterostructures were characterized by nitrogen adsorption/desorption isotherm measurement using a JW–BK132 F analyzer. The analysis of gas sensing performances was performed with a CGS–8 Series Intelligent Test Meter (China, ELITE TECH). 3. Results and discussion 3.1. Material synthesis and structural characterization The synthesis strategy for different samples and heterostructures is shown in Fig. 1. The shape of Zn2SnO4 nanomaterials depends on the various amount of raw materials and the addition of surfactant CTAB. In the hydrothermal process, a mass of nanocrystals could nucleate and then develop into a cubic morphology with high surface energies. When the concentration of raw materials was higher, the reactants dissolved and recrystallied fast during the crystal growth process and formed Zn2SnO4 with the rod shape [15]. Upon the introduction of surfactant CTAB, the surface energy could be tailored according to the capping of the nuclei’s surface, leading to the formation of Zn2SnO4 NOs [10]. In addition, all of the Zn2SnO4 samples could attach well on the surfaces of Mn3O4 because of the lattice matching. The XRD pattern in Fig. 2 shows the peaks of Mn3O4 NWs, NW–NCs, NW–NRs, and NW–NOs. The peaks of Mn3O4 NWs can be well assigned to JCPDS cards for Mn3O4 (18–0803). However, for NW–NCs, there are noticeable Mn3O4 peaks but no obvious Zn2SnO4 peaks in the pattern. From the magnified pattern in Fig. S1, one broad peak could be observed from 20–40°, which originated from the amorphous Zn2SnO4 phases and indicated the noncrystalline nature [16]. The peaks of NW–NRs and NW–NOs in Fig. 2 matched well with the JCPDS cards Mn3O4 (18–0803) and Zn2SnO4 (24–1470), also confirming the formation of Mn3O4/Zn2SnO4 heterostructures. The pristine Mn3O4 NWs are shown in Fig. S2, which have smooth surfaces without other nanostructures. After the deposition of Zn2SnO4, the Mn3O4 backbone surfaces were functionalized Zn2SnO4 NRs (Fig. 3a). These Zn2SnO4 NRs with a mean diameter of 20 nm cross

3.2. Fabrication and measurement of gas sensors The Mn3O4 NWs and different Mn3O4/Zn2SnO4 heterostructured materials were fabricated into gas sensor devices, which started with the preparation of the samples on a ceramic tube–electrode. The obtained sample powder (0.1 g) was ground and dispersed in deionized water (about 1/4 wt to the samples) to form uniform gray paste. Then, the paste acting as the sensitive layer (∼10 μm) was directly coated on the whole surface of the functional ceramic tube (diameter: 1.2 mm × length: 4.0 mm) with gold electrodes and platinum wires by a brush. A Ni–Cr alloy heating wire was used to control the operating temperature of the device and placed in the ceramic tube. The detailed schematic diagram of the sensing device and sensor structure was shown in Fig. S3. The gas sensing measurement was carried out by using the gas testing equipment, as shown in Fig. S4. As the target gas, acetone was injected into the glass chamber (1 L) by a micro-syringe.

Fig. 2. XRD pattern of Mn3O4 NWs, NW-NRs, NW-NCs and NW-NOs. 212

Sensors & Actuators: B. Chemical 290 (2019) 210–216

T. Zhou, et al.

Fig. 3. (a–b) FESEM images of NW-NRs, (c) schematic diagram of NW-NRs (d) TEM images of NW-NRs, (e–h) EDX mapping images of NW-NRs for Mn, Zn, Sn and O, (i–j) FESEM images of NW-NCs, (k) schematic diagram of NW-NCs (l) TEM images of NW-NCs, (m–p) EDX mapping images of NW-NCs for Mn, Zn, Sn and O, (q–r) FESEM images of NW-NOs, (s) schematic diagram of NW-NOs, (t) TEM images of NW-NOs and (u–x) EDX mapping images of NW-NOs for Mn, Zn, Sn and O.

Mn3O4 backbone not only remarkably improves the C3H6O sensing ability but also leads to a noticeable enhancement in selectivity. Fig. 5e shows the dynamic response–recovery characteristics of the NW–NOs–based sensor in the C3H6O concentrations varied from 10 to 200 ppm at 220 °C. The response curve dramatically rises under exposure to C3H6O while drops in air atmosphere. With C3H6O gas concentration increasing, the responses of the sensor based on NW–NOs appear to be a ladder–type improvement. The response values for 10, 20, 50, 100 and 200 ppm were 1.2, 2.0, 2.8, 6.1 and 8.3, respectively. Meanwhile, a relatively short response time of 3 s was obtained and the recovery time was within 120 s (Fig. 5f). Table 2 shows the acetone sensing performances of sensors based on different MOSs, which confirmed that the sensor based on NW–NOs exhibited much higher response and shorter response time than the others reported [25–30]. The response as a function of the C3H6O gas concentration is shown in Fig. 6a. The curve with a greater slope approximately presents a linear behavior from 10 to 200 ppm, demonstrating a relatively rapid increase in the response (Fig. 6a1). When above 200 ppm, the response increases slowly and tends to achieve a saturation condition (Fig. 6a2). Acetone, which is highly volatile and combustible, has been widely used for its extensive applications in laboratories and industry. Acetone can not only bring serious environmental damage but also cause irritation to noses, eyes, skin and central nervous system at concentrations higher than 450 mg/m3 (173 ppm) [31]. The detection range (10–200 ppm) satisfies the threshold limit value (TLV) and immediately dangerous to life or health (IDLH) detection limit (750 ppm/ 20000 ppm) for C3H6O according to the guidelines issued by the American Conference of Governmental Industrial Hygienists (ACGIH) and National Institute of Occupational Safety and Health (NIOSH) [32]. To investigate the stability and durability of NW–NOs as the sensing layer for gas devices, 5–cycle dynamic C3H6O sensing transients of NW–NOs were measured at 220 °C. Obviously, the curve of the sensor is highly reproducible (Fig. 6b). In addition, the fabricated three devices

After the sensor was placed in the glass chamber, the measurement was processed by using the CGS−8 intelligent testing system. The desired concentration of the test gas was obtained by the static liquid gas distribution method, which was calculated by the following formula [10], where c (ppm) is the target gas concentration, Φ is the required gas volume fraction, β (g/mL) is the density of the liquid, V1 (L) is the volume of liquid, V2 (L) is the volume of the chamber, and M (g/mol) is the molecular weight of the liquid. After the response was stable in the target gas, the sensors were transferred to a closed glass chamber which is full of ambient air for the recovery process. The sensing response is expressed as Ra/Rg, where Ra and Rg are the steady–state resistance values recorded in air and in target gas, respectively. The response/ recovery time is evaluated to reach 90% of the overall resistance change.

c=

22.4 × f× β× V1 M×V2 × 1000

Chemical sensing experiments of pure NWs, NW–NCs, NW–NRs and NW–NOs were conducted in the temperature range from 180–280 °C for 200 ppm acetone (C3H6O), formaldehyde (CH2O), benzene (C6H6), toluene (C7H8), and xylene (C8H10) (Fig. 5a–d). The Mn3O4 NWs–based sensor shows a lowly sensitive detection for C3H6O, CH2O, C6H6, C7H8 and C8H10. The response value is less than 1.3 as shown in Fig. 5a. Considering that the additional active sites of Zn2SnO4 on the primal material surfaces may provide the activity as reported previously by Shu et al. [24], it is reasonable that the Mn3O4/Zn2SnO4 heterostructure can exhibit an enhanced sensing performance compared with pure Mn3O4. Fig. 5b–d displays the responses of NW–NCs, NW–NRs and NW–NOs with respect to the different gases. The NW–NCs and NW–NRs–based sensors exhibited an inapparent improvement for the responses of gases (Ra/Rg < 4), whereas the response of C3H6O for NW–NOs was improved significantly at 220 °C (Ra/Rg = 8.3). Results demonstrate that appropriate loading of Zn2SnO4 nanoparticles on 213

Sensors & Actuators: B. Chemical 290 (2019) 210–216

T. Zhou, et al.

Fig. 4. HRTEM images of (a) Mn3O4 NWs, (b) Zn2SnO4 NRs, (c) Zn2SnO4 NCs and (d) Zn2SnO4 NOs in Mn3O4/Zn2SnO4 heterojunction. XPS analysis of (e) Zn 2p spectrum, (f) Sn 3d spectrum and (g) Mn 2p spectrum for the NW-NOs. XPS analysis of O 1s spectrum for NW-NRs, NW-NCs and NW-NOs.

Fig. 5. (a–d) Gas responses to different gases (C3H6O, CH2O, C7H8, C6H6 and C8H10) of the gas sensor based on Mn3O4 NWs, NW-NCs, NW-NRs and NW-NOs at different operating temperatures from 180 to 280 °C; (e) response transients (220 °C) of NW-NOs based sensor to 10–200 ppm C3H6O; (f) resistance curves of NWNOs-based sensors to 200 ppm C3H6O at 220 °C. 214

Sensors & Actuators: B. Chemical 290 (2019) 210–216

T. Zhou, et al.

Fig. 6. The relationship of C3H6O response vs the C3H6O concentration (10–1500 ppm) for NW-NOs based sensor (Error bars show the standard deviation for n = 3 measurements.); (a1) the responses of NW-NOs based sensor to 10–200 ppm C3H6O; (a2) the responses of NW-NOs based sensor to 500–1500 ppm C3H6O; (b) reproducibility of the NW-NOs based sensor upon exposure (5 cycles) 200 ppm C3H6O at 220 °C; (c) resistance transients (220 °C) of three devices to 200 ppm C3H6O; (d) long–term stability (15 days) of NW-NOs based sensor. (Error bars show the standard deviation for n = 3 measurements.).

of NW–NOs exhibited the similar change of resistance and sensing performances, indicating the excellent repeatability (Fig. 6c). To evaluate the long–term stability, the sensing response and resistance (Ra and Rg) to 200 ppm C3H6O at 220 °C were investigated over 15–day period in Figs. 6d and S5. The sensor based on NW–NOs retained the high response and stable resistance without obvious decrease. Then the responses were measured for 15 days after 4 months (Fig. S6), which demonstrates that the sensor possesses long–term sensing activity and permits continuous and cycling operations.

Table 1 Fitting results of O 1s XPS spectra of NW-NRs, NW-NCs and NW-NOs. Materials

Oxygen species

Binding energy(eV)

Relative percentage(%)

NW-NRs

OL OV OC OL OV OC OL OV OC

530.32 531.14 532.09 530.30 531.10 532.23 529.30 530.46 532.03

30.0 30.6 39.4 26.6 44.9 28.5 15.8 30.0 54.2

NW-NCs

NW-NOs

3.3. Gas sensing mechanism The widely accepted sensing mechanism for surface resistance–type MOSs based gas sensors is closely associated with the space–charge layer mode [33–35]. For p–type Mn3O4 NWs, oxygen molecule could adsorb on the surface and ionize into O− by taking the electrons from the surfaces of Mn3O4 NWs, which leaded to the formation of a hole–accumulation layer. When Mn3O4 NWs were exposed to acetone atmosphere, the acetone was oxidized by the oxygen species and electrons were fed back into the sensing layer, resulting in the increase of the resistance [36,37]. Mn3O4/Zn2SnO4 based sensors displayed the enhanced C3H6O sensing performances, which could be well interpreted by creating the smart 1D architecture, combined with p–n hybrid junctions at the sensing layer interfaces. The effective electronic interaction could occur at the physical interface between Mn3O4 NWs and the Zn2SnO4 nano–units, leading to formation of charge depletion and the transfer of charge. Thus, the enhanced conductance modulation results the better acetone sensing properties. For our work, various Mn3O4/Zn2SnO4 heterostructures exhibited different sensing performances. We believe that it relates to the capacity of adsorbing oxygen of sensing layer [21,23]. As shown in Table 1, the percentages of OC for NW–NRs, NW–NCs and NW–NOs were calculated to be 39.4%, 28.5% and 54.2% from XPS analysis, respectively. That is, the relative percentages of OC component follow the order of NW–NOs > NW–NRs > NW–NCs, which is consistent with the order of the C3H6O sensitivity. Obviously, NW–NOs with the 1D structure possess the better oxygen–chemisorbing ability and are able to absorb more oxygen species during the sensing process than the other two hybrid materials. Therefore, the construction of special 1D structure is

Table 2 Comparison of the acetone-sensing performances of different sensors based on MOSs. Materials

Conc. [ppm]

Tem. [° C]

Res.[Ra/Rg or Rg/Ra]

Tres [s]

Ref.

TiO2 α-Fe2O3/SnO2 NiO-TeO2 AuPd-WO3 Sn-ZnO WO3-NiO Mn3O4/Zn2SnO4

100 100 500 200 200 200 200

270 275 125 300 300 300 220

4.25 5.3 6.01 1.52 6.3 4.4 8.3

10 1.5 ˜90 101 7 51 3

[25] [26] [27] [28] [29] [30] This work

◆Conc.: Concentration; ◆Tem.: Temperature; ◆Res.: Response; ◆Tres: Response time; ◆ Ref.: Reference.

likely to exhibit the outstanding sensing performance in gas sensors. 4. Conclusion To summarize, 1D Mn3O4 NWs decorated different Zn2SnO4 nanostructures with the shape of rods, cubes and octahedrons were synthesized by a facile two–step hydrothermal method and evaluated as effective CSs. By loading the Zn2SnO4 nano–building–blocks onto Mn3O4 NWs, we can realize p–n heterojunction construction and achieve gas sensors with high performances. Such devices have 215

Sensors & Actuators: B. Chemical 290 (2019) 210–216

T. Zhou, et al.

exhibited improved sensitivity to C3H6O (Ra/Rg = 8.3), fast response (ca. 3 s), high stability, and excellent fabrication repeatability. The good sensing behavior is related to the superrich surface adsorbed oxygen existed in the special 1D heterogeneous structure. The CSs based on NW–NOs may be applied in some practical C3H6O detection fields where the high response and fast monitoring process are simultaneously needed.

[15]

[16]

Acknowledgement

[17]

This work was supported by the Natural Science Foundation Committee (NSFC, Grant No. 61673191), Science and Technology Development Plan of Jilin Province (Grant No. 20180414025 GH).

[18]

[19]

Appendix A. Supplementary data [20]

Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.snb.2019.03.048.

[21]

References [22] [1] J.W. Yoon, J.H. Lee, Toward breath analysis on a chip for disease diagnosis using semiconductor–based chemiresistors: recent progress and future perspectives, Lab Chip 17 (2017) 3537–3557. [2] L.L. Wang, S. Chen, W. Li, K. Wang, Z. Lou, G.Z. Shen, Grain-boundary-induced drastic sensing performance enhancement of polycrystalline-microwire printed gas sensors, Adv. Mater. 1804583 (2018). [3] O. Lupan, V. Postica, N. Wolff, O. Polonskyi, V. Duppel, V. Kaidas, E. Lazari, N. Ababii, F. Faupel, L. Kienle, R. Adelung, Localized synthesis of iron oxide nanowires and fabrication of high performance nanosensors based on a single Fe2O3 nanowire, Small 13 (2017) 1602868. [4] A.A. Abokifa, K. Haddad, J. Fortner, C.S. Lo, P. Biswas. Sensing mechanism of ethanol and acetone at room temperature by SnO2 nano–columns synthesized by aerosol routes: theoretical calculations compared to experimental results, J. Mater. Chem. A 6 (2018) 2053–2066. [5] J.W. Kim, Y. Porte, K.Y. Ko, H. Kim, J.M. Myoung, Micropatternable double–raced ZnO nanoflowers for flexible gas sensor, ACS Appl. Mater. Interfaces 9 (2017) 32876–32886. [6] J.W. Yoon, Y.J. Hong, G.D. Park, S.J. Hwang, F. Abdel–Hady, A.A. Wazzan, Y.C. Kang, J.H. Lee, Kilogram–scale synthesis of Pd–loaded quintuple-shelled Co3O4 microreactors and their application to ultrasensitive and ultraselective detection of methylbenzenes, ACS Appl. Mater. Interfaces 7 (2015) 7717–7723. [7] Z.J. Li, N.N. Wang, Z.J. Lin, J.Q. Wang, W. Liu, K. Sun, Y.Q. Fu, Z.G. Wang, Room–temperature high–performance H2S sensor based on porous CuO nanosheets prepared by hydrothermal method, ACS Appl. Mater. Interfaces 8 (2016) 20962–20968. [8] T. Larbi, L. Ben said, A. Ben daly, B. Ouni, A. Labidi, M. Amlouk, Ethanol sensing properties and photocatalytic degradation of methylene blue by Mn3O4, NiMn2O4 and alloys of Ni–manganates thin films, J. Alloys Compd. 686 (2016) 168–175. [9] S.H. Lee, V. Galstyan, A. Ponzoni, I. Gonzalo-Juan, R. Riedel, M.A. Dourges, Y. Nicolas, T. Toupance, Finely tuned SnO2 nanoparticles for efficient detection of reducing and oxidizing gases: the influence of alkali metal cation on gas sensing properties, ACS Appl. Mater. Interfaces 10 (2018) 10173–10184. [10] L.L. Wang, T.T. Zhou, R. Zhang, Z. Lou, J.N. Deng, T. Zhang, Comparison of toluene sensing performances of zinc stannate with different morphology−based gas sensors, Sens. Actuators B Chem. 227 (2016) 448–455. [11] D.R. Miller, S.A. Akbar, P.A. Morris, Nanoscale metal oxide-based heterojunctions for gas sensing: a review, Sens. Actuators B Chem. 204 (2014) 250–272. [12] J.N. Deng, L.L. Wang, Z. Lou, T. Zhang, Design of CuO–TiO2 heterostructure nanofibers and their sensing performance, J. Mater. Chem. A 2 (2014) 9030–9034. [13] C.W. Na, S.Y. Park, J.H. Chung, J.H. Lee, Transformation of ZnO nanobelts into single−crystalline Mn3O4 nanowires, ACS Appl. Mater. Interfaces 4 (2012) 6565–6572. [14] T.T. Zhou, X.P. Liu, R. Zhang, L.L. Wang, T. Zhang, Constructing hierarchical

[23]

[24]

[25]

[26]

[27]

[28] [29] [30] [31]

[32]

[33]

[34]

[35]

[36]

[37]

216

heterostructured Mn3O4/Zn2SnO4 haterials for efficient gas sensing reaction, Adv. Mater. Interfaces (2018) 1800115. G.X. Ma, R.J. Zou, L. Jiang, Z.Y. Zhang, Y.F. Xue, L. Yu, G.S. Song, W.Y. Li, J.Q. Hu, Phase-controlled synthesis and gas-sensing properties of zinc stannate (ZnSnO3 and Zn2SnO4) faceted solid and hollow microcrystals, CrystEngComm 14 (2012) 2172–2179. S.H. Choi, D. Hwang, D.Y. Kim, Y. Kervella, P. Maldivi, S.Y. Jang, R. Demadrille, I.D. Kim, Amorphous zinc stannate (Zn2SnO4) nanofibers networks as photoelectrodes for organic dye−sensitized solar cells, Adv. Funct. Mater. 23 (2013) 3146–3155. H.M. Yang, S.Y. Ma, G.J. Yang, Q. Chen, Q.Z. Zeng, Q. Ge, L. Ma, Y. Tie, Synthesis of La2O3 doped Zn2SnO4 hollow fibers by electrospinning method and application in detecting of acetone, Appl. Surf. Sci. 425 (2017) 585–593. X. Zhou, X.W. Li, H.B. Sun, P. Sun, X.S. Liang, F.M. Liu, X.L. Hu, G.Y. Lu, Nanosheet−assembled ZnFe2O4 hollow microspheres for high−sensitive acetone sensor, ACS Appl. Mater. Interfaces 7 (2015) 15414–15421. N. Li, Y. Tian, J.H. Zhao, J. Zhang, J. Zhang, W. Zuo, Y. Ding, Efficient removal of chromium from water by Mn3O4@ZnO/Mn3O4 composite under simulated sunlight irradiation: synergy of photocatalytic reduction and adsorption, Appl. Catal. B−Environ. 214 (2017) 126–136. Z.W. Zhao, J.H. Zhao, C. Yang, Efficient removal of ciprofloxacin by peroxymonosulfate/Mn3O4−MnO2 catalytic oxidation system, Chem. Eng. J. 327 (2017) 481–489. J.J. Ouyang, J. Pei, Q. Kuang, Z.X. Xie, L.S. Zheng, Supersaturation−controlled shape evolution of α−Fe2O3 nanocrystals and their facet−dependent catalytic and sensing properties, ACS Appl. Mater. Interfaces 6 (2014) 12505–12514. J.C. Dupin, D. Gonbeau, P. Vinatier, A. Levasseur, Systematic XPS studies of metal oxides, hydroxides, and peroxides, Phys. Chem. Chem. Phys. 2 (2000) 1319–1324. L.Q. Sun, X. Han, K. Liu, S. Yin, Q.L. Chen, Q. Kuang, X.G. Han, Z.X. Xie, C. Wang, Template−free construction of hollow α−Fe2O3 hexagonal nanocolumn particles with an exposed special surface for advanced gas sensing properties, Nanoscale 7 (2015) 9416–9420. S.M. Shu, M.X. Wang, W. Yang, S.T. Liu, Synthesis of surface layered hierarchical octahedral−like structured Zn2SnO4/SnO2 with excellent sensing properties toward HCHO, Sens. Actuators B Chem. 243 (2017) 1171–1180. S.T. Navale, Z.B. Yang, Chenshitao Liu, P.J. Cao, V.B. Patil, N.S. Ramgir, R.S. Mane, F.J. Stadler, Enhanced acetone sensing properties of titanium dioxide nanoparticles with a sub-ppm detection limit, Sens. Actuators B Chem. 255 (2018) 1701–1710. X. Li, H. Zhang, C.H. Feng, Y.F. Sun, J. Ma, C. Wang, G.Y. Lu, Novel cage-like aFe2O3/SnO2 composite nanofibers by electrospinning for rapid gas sensing properties, RSC Adv. 4 (2014) 27552–27555. S. Park, G.J. Sun, H. Kheel, S. Choi, C. Lee, Acetone gas sensing properties of NiO particle-decorated TeO2 nanorod sensors, J. Nanosci. Nanotechnol. 16 (2016) 8589–8593. S. Kim, S. Park, S. Park, C. Lee, Acetone sensing of Au and Pd-decorated WO3 nanorod sensors, Sens. Actuators B Chem. 209 (2015) 180–185. S. Sinha, Synthesis of 1D Sn-doped ZnO hierarchical nanorods with enhanced gas sensing characteristics, Ceram. Int. 41 (2015) 13676–13684. S. Choi, J.K. Lee, W.S. Lee, C. Lee, W.I. Lee, Acetone sensing of multi-networked WO3-NiO core-shell nanorod sensors, J. Korean Phys. Soc. 71 (2017) 487–493. X.J. Liu, X.Y. Tian, X.M. Jiang, L. Jiang, P.Y. Hou, S.W. Zhang, X. Sun, H.C. Yang, R.Y. Cao, X.J. Xu, Facile preparation of hierarchical Sb-doped In2O3 microstructures for acetone detection, Sens. Actuators B 270 (2018) 304–311. A. Mirzaei, S.G. Leonardi, G. Neri, Detection of hazardous volatile organic compounds (VOCs) by metal oxide nanostructures−based gas sensors: a review, Ceram. Int. 42 (2016) 15119–15141. A.Sutka, R. Pärna, G. Mezinskis, V. Kisand, Effects of Co ion addition and annealing conditions on nickel ferrite gas response, Sens. Actuators B Chem. 192 (2014) 173–180. T.H. Kim, C.H. Kwak, J.H. Lee, NiO/NiWO4 composite yolk-shell spheres with nanoscale NiO outer layer for ultrasensitive and selective detection of subppm-level pxylene, ACS Appl. Mater. Interfaces 9 (2017) 32034–32043. X.Z. Song, F.F. Sun, S.T. Dai, X. Lin, K.M. Sun, X.F. Wang, Hollow NiFe2O4 microspindles derived from Ni/Fe bimetallic MOFs for highly sensitive acetone sensing at low operating temperatures, Inorg. Chem. Front. 5 (2018) 1107–1114. Z.F. Dai, C.S. Lee, Y.H. Tian, I.D. Kim, J.H. Lee, Highly reversible switching from P– to N–type NO2 sensing in a monolayer Fe2O3 inverse opal film and the associated p–n transition phase diagram, J. Mater. Chem. A 3 (2015) 3372–3381. H.J. Kim, J.H. Lee, Highly sensitive and selective gas sensors using p-type oxide semiconductors: overview, Sens. Actuators B Chem. 192 (2014) 607–627.