Investigation on photocatalysis and room temperature gas sensing of MoS2-ZnO nanocomposite synthesized by hydrothermal method
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摘要: 为开发一种高性能、可回收、低成本的光催化剂，本论文使用水热法制备了多孔结构的ZnO纳米片复合MoS2 (MoS2-ZnO) 光催化材料。通过XRD、SEM、光致发光光谱(PL)、XPS等手段对样品的形貌、光学性质等进行了测试表征。结果表明，所制备的MoS2-ZnO样品为多孔片状结构；这种复合结构中MoS2不仅有助于增强ZnO中光生载流子的分离效率，而且还能增强可见光区的吸收，从而提高光催化和气敏性能。在模拟太阳光下，MoS2-ZnO纳米复合材料对高浓度(15 mg/L)的亚甲基蓝染液(MB)表现出较高的光催化降解活性。同时，MoS2-ZnO制备的气敏传感器对低浓度(2.05 mg/m3)NO2还具有较高的灵敏度。本工作为制备高效太阳能驱动的光催化剂和气体传感器提供了重要参考。Abstract: To develop a high performance, recyclable, low cost photocatalyst. In this work, MoS2 modified ZnO (MoS2-ZnO) nanocomposites were prepared by a hydrothermal method. The morphology and optical properties of the samples were characterized by XRD, SEM, photoluminescence spectroscopy (PL) and XPS. We find that the prepared MoS2-ZnO samples own a porous structure from SEM. And MoS2 can not only enhance the separation efficiency of photocarriers in MoS2-ZnO, but also increase the absorption of visible light region, resulting in improving the photo-catalytic and gas sensitive properties. Under simulated sunlight, the MoS2-ZnO nanocomposite exhibits high photo-catalytic degradation activity for high concentration (15 mg/L) methylene blue dye (MB). At the same time, the MoS2-ZnO-based gas sensor possesses a high sensitivity for NO2 concentration of 2.05 mg/m3. This work offers a simple strategy to prepare highly efficient visible light-driven photocatalysts and gas sensors.
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Key words:
- ZnO /
- MoS2 /
- photocatalysis /
- gas sensing /
- methylene blue /
- porous structure /
- nanocomposite
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图 2 ((a)~(c)) 1.75%MoS2-ZnO样品的SEM图像；(d) 1.75%MoS2-ZnO样品的EDS图谱；(e) 纯MoS2图像；(f) 1.75%MoS2-ZnO的TEM图像
Figure 2. ((a)-(c)) SEM images of the 1.75%MoS2-ZnO sample; (d) EDS diagram of 1.75%MoS2-ZnO sample; (e) SEM image of the pure MoS2; (f) TEM image of 1.75%MoS2-ZnO sample
图 3 MoS2-ZnO样品的XPS图谱: (a) 全谱; (b) Zn2p; (c) S2p; (d) Mo3d; (e) O1s
Figure 3. XPS spectra of MoS2-ZnO samples: (a) Survey spectra; (b) Zn2p;(c) S2p; (d) Mo3d; (d) O1s
LMM—Auger electron spectroscopy
图 4 MoS2-ZnO样品的光致发光光谱 (PL)
Figure 4. Photoluminescence spectroscopy (PL) of the MoS2-ZnO samples
图 5 MoS2-ZnO样品的紫外可见吸收光谱 (a) 和禁带宽度 (b)
Figure 5. UV-Vis absorption spectra (a) and band gaps (b) of the MoS2-ZnO samples
图 6 1.75%MoS2-ZnO和ZnO颗粒的N2吸附-脱附等温线
Figure 6. N2 adsorption-desorption isotherm of 1.75%MoS2-ZnO and ZnO particles
STP—Standard temperature and pressure
图 8 (a) MoS2-ZnO样品在模拟阳光下的MB光降解曲线; (b)在模拟阳光下MB的拟合曲线; (c)在不同pH条件和模拟的阳光下1.75%MoS2-ZnO的MB降解曲线; (d)在模拟阳光下对MB、RhB和MO进行光降解; (e)在模拟阳光下五个周期内1.75%MoS2-ZnO样品的MB降解; (f)在模拟阳光下，不同牺牲剂对MB的1.75%MoS2-ZnO纳米异质结构的光催化降解效率(PCD)的影响
Figure 8. (a) MB photodegradation curves for the MoS2-ZnO samples under simulated sunlight; (b) Fitted curves for MB under simulated sunlight; (c) MB degradation curves for 1.75%MoS2-ZnO under different pH conditions and simulated sunlight; (d) Photodegradation of MB, RhB and MO under simulated sunlight; (e) MB degradation by the 1.75%MoS2-ZnO sample over five cycles under simulated sunlight; (f) Effects of different quenchers on the photocatalytic degradation efficiency (PCD) of the 1.75%MoS2-ZnO nanoheterostructure for MB under simulated sunlight
K—Quasi first order kinetic constant; c0—Initial solution concentration; ct—Solution measurement concentration; MB—Methylene blue; RhB—Rhodamine B; MO—Methyl orange; EDTA-2Na—Ethylenediaminetetraacetic acid disodium salt; IPA—Iso-propyl alcohol; BQ—1, 4-Benzoquinone
图 9 室温紫外光下MoS2-ZnO传感器对NO2的动态响应曲线
Figure 9. Dynamic response curves of sensors based on MoS2-ZnO to NO2 by UV-light at room temperature
Rg—Measuring the resistance; R0—Initial resistance
图 10 (a) MoS2-ZnO光催化机制；(b) MoS2-ZnO气敏机制
Figure 10. (a) Photocatalysis mechanism of MoS2-ZnO; (b) Gas sensitivity mechanism of MoS2-ZnO
ECB—Conduction band; Ef—Band gap; EVB—Valence band; MB—Ethylene blue
表 1 MoS2-ZnO样品成分配比
Table 1. Composition ratio of MoS2-ZnO samples
Samples Mole ratio of n(Zn): n(Mo) 0%MoS2-ZnO
1%MoS2-ZnO
1.75%MoS2-ZnO
2.5%MoS2-ZnO100∶0
99∶1
98.25∶1.75
97.5∶2.5
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表 2 根据XRD计算得到的MoS2-ZnO样品晶粒尺寸
Table 2. Grain size calculated according to XRD datas of MoS2-ZnO samples
Samples 0%MoS2-ZnO 1%MoS2-ZnO 1.75%MoS2-ZnO 2.5%MoS2-ZnO Grain size/nm 25.66 25.59 25.65 25.61
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表 3 1.75%MoS2-ZnO和ZnO颗粒的比表面积、孔径及孔体积
Table 3. Specific surface area, pore size and pore volume data of 1.75%MoS2-ZnO and ZnO particles
Samples Surface area/(m2·g−1) Average pore sizes/nm Pore volume/(cm3·g−1) 1.75%MoS2-ZnO
ZnO particles32.09
22.5116.15
15.320.1296
0.0862
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