| With the improvement of industrialization,the energy crisis and environmental pollution are also facing severe tests.Semiconductor photocatalytic degradation technology provides a new and effective method for energy and environmental issues.Cd S and Bi OCl,as good photocatalytic materials,have attracted extensive attention for their unique energy bands.However,Cd S has photo-corrosion and Bi OCl has low utilization of visible light.In order to improve its deficiencies,the experiment uses WS2 and Mo S2 as cocatalysts to modify the surface of Cd S and Bi OCl,respectively,to build a heterojunction.In this paper,XRD,SEM,TEM,UV-Vis DRS,PL,EIS and other characterization methods are used to study the morphology of heterojunctions,the recombination efficiency of electron-hole pairs,and the mobility of photogenerated carriers.The degradation of methylene blue?MB?by various composite materials was analyzed.Finally,the photocatalytic mechanism of composite materials was studied.WS2/Cd S and WS2/Mo S2/Cd S?referred to as WMC?composites are prepared by co-precipitation-hydrothermal method.It was found that WS2 and Mo S2 are coated with Cd S particles to form WS2/Cd S and WMC heterojunction structures.The incorporation of WS2 and Mo S2 increases the photoresponse range of Cd S,reduces the band gap of Cd S,enhances the mobility of photo-generated carriers,and the composite efficiency of WMC electron-hole pairs is lower than WS2/Cd S.At 240 min of photocatalysis,the highest photocatalytic efficiency were 5%-WS2/Cd S and 5%-WMC,respectively.Among them,the degradation efficiency of 5%-WS2/Cd S to MB?10 mg/L?is 81.79%,and the degradation efficiency of 5%-WMC to MB?10 mg/L?is 98.15%.According to the first-order reaction kinetics simulation,the reaction rate constant of5%-WMC is 0.01866 min-1,which is 6.2 times and 2.5 times that of Cd S and5%-WS2/Cd S,respectively.After 4 cycles of experiments,the catalytic activity did not decrease significantly.The active groups in the photocatalytic degradation mechanism.WS2/Bi OCl and WS2/Mo S2/Bi OCl?abbreviated as WMB?composites are prepared by in-situ construction.It was found that WS2/Bi OCl and WMB crystallized well.With the increase of the mass ratio of WS2 and Mo S2,the XRD diffraction peaks of WS2 and Mo S2 in the composite gradually become apparent,the visible light response range of Bi OCl increases,the band gap decreases,and the photogenerated electron-hole pair recombination probability decreases.Mo S2and Bi OCl are stacked on the WS2 sheet to form a WS2/Bi OCl and WMB heterojunction structure.At 240 min of photocatalysis,the degradation efficiencies of 7%-WS2/Bi OCl and 7%-WMB reach at 95.83%and 99.36%,respectively.The active groups in the photocatalytic degradation process in both systems are·OH and h+.According to the first-order reaction kinetics simulation,the reaction rate constant of 7%-WMB is 0.0248 min-1,which is 6.7 times and1.6 times that of Bi OCl and 7%-WS2/Bi OCl,respectively.After 4 cycles of experiments,it still has high catalytic activity. |
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