Preparation Of Cadmium Sulfide-based Composites For Photocatalytic Hydrogen Production

Hydrogen energy has been widely recognized as an effective substitute to fossil fuels for its cleanliness and high-energy density.Photocatalytic hydrogen evolution,which uses solar power to produce hydrogen efficiently,is a promising hydrogen production strategy.Since the discovery of photocatalytic splitting water for hydrogen production with TiO₂,the development of new semiconductor catalysts presented an accelerating trend.In the various semiconductors being studied,cadmium sulfide?CdS?has gained extensive attention because of its relatively narrow band gap of 2.42e V.However,the pure CdS should be further studied due to its problems of poor chemical stability,severe photo-corrosion and low catalytic activity.In this study,a double-lattice structure zinc cadmium sulfide(Zn_xCd_1-xS)solid solution was prepared and a non-precious metal co-catalyst nickel phosphide?Ni₂P?was modified on the surface of Zn_xCd_1-xS.Morever,a core-shell structure zinc cadmium sulfide(Zn_xCd_1-xS)nanometer was prepared,followed by modified with non-precious metal cocatalyst tungsten sulfide?WS₂?nanosheets on its surface.The photodegradation performance of the catalyst was investigated.The specific researches content are as follows:?1?Preparation of Ni₂P/Zn_xCd_1-xS composite material and study of its performance in hydrogen production by photolysis of water.First,the Zn_xCd_1-xS solid solution with a double-lattice structure was prepared by hydrothermal precipitation,and then Ni₂P was supported on the twinned Zn_0.5Cd_0.5S?ZCS?nanocrystals by in-situ growth.When the loading amount of Ni₂P is 4wt%,the prepared photocatalyst exhibits excellent visible light catalytic hydrogen production active,and the highest hydrogen production rate is 30473?mol h^-1 g^-1 and the apparent quantum yield can reach 83.5%.Under visible light???420nm?,after 4cycles?16 h?of continuous catalytic process,the hydrogen production activity can be maintained above 90.5%relative to the original value.The unique nano-double-stranded structure of ZCS and the synergy between Ni₂P and double-stranded ZCS have significantly improved the catalytic activity of the composite photocatalyst.?2?Preparation of WS₂/CdS@Zn CdS composite material and study of its performance in hydrogen production by photolysis of water.Under low-temperature hydrothermal conditions,the CdS@Zn CdS?CdS@ZCS?nanomaterials combined one-dimensional nanorods with core-shell structure were successfully prepared.In addition,WS₂ nanosheets are electrostatically coupled to the surface of CdS@ZCS.Zeta potential,TEM,XPS and other testing methods have fully proved that the close bonding between WS₂ nanosheets and CdS@ZCS nanorods.WS₂/CdS@ZCS exhibits good visible light catalytic activity.The highest hydrogen production rate is 34860?mol h^-1 g^-1,which is about 5.2 times that of CdS nanorods(6730?mol h^-1 g^-1).In addition,WS₂/CdS@ZCS showed high photocatalytic stability after continuous catalytic reaction for 4 hours in 4 cycles.Therefore,the introduction photocatalytic activity of CdS nanorods.A possible mechanism for the photocatalytic enhancement of its core/shell structure WS₂/CdS@ZCS was proposed.This work demonstrates a low-cost,high-efficiency method for modifying low-activity CdS,combined it with dual-lattice nanostructures,core-shell structures,and sheet?2D?structures,giving full play the role of structure to regulate the activity of nanocatalyst.