Preparation And Photocatalytic Performance Of Micro/nano-Structured CdS Composite

Metal sulfides are a class of catalysts with high visible light activity and have potential applications in the degradation of organic pollutants.However,the stability of simple binary metal sulfides is poor,which is prone to photo-corrosion in the photocatalysis process.That is,the faster photoionization electron-hole combination limits its further application.It is found that the bandgap,crystal structure,lattice defects and surface morphology of the semiconductor affect the photocatalytic activity.In this dissertation,we systematically studied the controllable preparation,surface morphology,crystal phase composition and photocatalytic properties of cadmium sulfide(CdS),reduced graphene oxide(rGO)and zinc oxide(ZnO)composites,and obtained new research results in the preparation of higher photocatalytic performance CdS / nanocomposites.(1)This paper reports the synthesis of CdS QDs/rGO composites using the surfactant polyvinylpyrrolidone(PVP)as a dispersant and sonicating in a boiling water bath.Graphene oxide(GO)is mostly reduced to rGO after a long reaction time under boiling water bath conditions.In this method,the hydrophobic interaction between the PVP and the rGO-conjugated charcoal raises the homogeneous distribution of rGO.Ultrasound and PVP also play an important role in the uniform dispersion of CdS on the rGO surface.The synthesized composite material significantly enhanced the visible light absorption,and we also found that the prepared composite has a higher capability of degrading the photocatalytic organic dye after heat treatment at a proper temperature.(2)Three-dimensional(3D)snowflake-like CdS-rGO composites were synthesized by a simple hydrothermal method using L-aspartic acid as a green template.We also found that L-aspartic acid and temperature have a significant influence on the morphology of CdS crystals during the preparation process.Experiments on photocatalytic degradation of RhB aqueous solution under simulated solar irradiation show that the prepared 3D CdS-rGO can effectively improve the photocatalytic activity and reusability.(3)The urea and zinc acetate were added on the basis of three-dimensional snow-like CdS synthesized by using L-aspartic acid as a green template agent,and the mesoporous flower-like CdS-ZnO composite was prepared by heating and stirring in an oil bath.ZnO in the composite material has a film-like structure,which adhereswell to the snowflake-like CdS semiconductor branches and effectively increases the reactive sites of the composite material.At the same time,due to the introduction of zinc oxide,heterogeneous energy level staggered structures are formed in the catalyst,which effectively prolongs the lifetime of the carriers,widens the absorption range of the light,increases the light utilization rate,and improves the photocatalytic activity of the composite.