Preparation Of Cadmium Sulfide Heterojunction And Its Photocatalytic Application

With the development of global economy and industrialization,the decrease of the reserves of traditional energy and the aggravation of environmental pollution are the two main obstacles to sustainable development.The outstanding performance of semiconductor photocatalysis technology in environmental pollution control and clean energy production is considered to be one of the important solutions to this problem.The effective photocatalyst should have the following points:high efficiency of light absorption,separation and transfer efficiency of photoelectron hole pair,excellent conversion efficiency and so on.A single-component semiconductor can hardly meet all these requirements at the same time.Therefore,the research of composite photocatalyst with multi-materials has attracted a lot of people’s attention.Cd S is widely used in the research of photocatalysis because of its excellent visible light response and photoelectric conversion efficiency.However,high photoelectron hole recombination and serious photoetching hinder its further development.In this paper,we will design and fabricate the heterostructure around Cd S to form a multi-channel carrier transfer path composite material.The reaction efficiency in photocatalysis was improved.This paper will be divided into the following three parts:（1）Three core-shell materials,Au@Cd S,Au@Ag₂S and Au@Zn O,were prepared to investigate the relationship between the hot electron transfer efficiency and the Schottky barrier height in the photocatalyst of metal semiconductor system.In this paper,we used three kinds of materials as SERS substrates to in-situ Raman detection of PATP molecule,and monitored the conversion rate of PATP molecule to DMAB.And the degradation efficiency of the three materials in photocatalytic degradation of Rhodamine B was studied.The results show that the transfer efficiency of hot electrons is highly correlated with the Schottky barrier at the interface of the metal semiconductor structure.（2）By fine-tuning the core-shell structure of Au@Cd S in the first work,the Cd S/C₃N₄-bonded heterostructures were prepared by anion exchange and chemical adsorption,Au@Cd S/C₃N₄ ternary yolk double-shell nanostructure with Au core.By adjusting the amount of C₃N₄ coating on Cd S,the optimum proportion of the composite in photocatalysis was investigated.Based on the results of the characterization and the verification of the photocatalytic efficiency,the improvement of the photocatalytic performance of the ternary composite was realized and the enhancement mechanism of the photocatalytic activity was discussed.（3）The ternary Z-type heterojunction photocatalyst C₃N₄/Ti₃C₂/Cd S was designed and prepared by in-situ synthesis.Firstly,the in situ growth of C₃N₄ on Ti₃C₂ was carried out by mixing urea solution with Ti₃C₂,secondly,the intermediate C₃N₄/Ti₃C₂ was mixed with the precursor solution of Cd S for in situ growth of Cd S.Then the optimum ratio of photocatalyst was investigated by comparing the yield of hydrogen peroxide produced by photocatalyst under visible light.Based on the experimental results of photocatalytic hydrogen peroxide production and the analysis of energy band structure,the possible mechanism of practical photocatalytic enhancement was analyzed.