Synthesis Of Zn_xCd_1-xS Nanomaterials For Photocatalytic H₂ Evolution

Semiconductor photocatalytic decomposition of water to produce hydrogen（HER）has received widespread attention because its energy source is solar energy and the reaction product is hydrogen（H₂）,which has high energy density and no pollution.However,this reaction has very stringent requirements for the semiconductor materials used as catalysts.It requires suitable valence band（VB）,conduction band position（CB）,suitable forbidden band width（Eg）,and efficient electron-hole separation efficiency.The materials are cheap and easy to obtain,and the synthesis method is safe and convenient.This thesis has done some research around the above-mentioned problems.The research work consists of the following four aspects:（1）Select the classic cadmium sulfide（Cd S）as the catalyst,and improve the series of problems encountered by Cd S in the reaction process;（2）While improving the stability,through mixing The hetero-non-precious metal Ni further improves the HER performance of the Cd S-based photocatalyst;（3）We synthesized a nanotube-structured Znx Cd1-x S solid solution catalyst and conducted a HER performance test.Through a series of characterizations,the reasons for the performance improvement were explained.In our work,a series of Zn_xCd_1-xS solid solution hollow sphere photocatalytic materials were first synthesized,and their performance was tested by photocatalytic water splitting to produce hydrogen.The sample with the best activity was determined to be Zn_0.8Cd_0.2S（ZCS）,The hydrogen production rate is 7.25mmol·h^-1·g^-1.In order to further improve the photocatalytic performance of the sample,the non-noble metal Ni was selected for modification,and the optimal doping content was determined to be 5wt%.At this time,the hydrogen production rate of the ZCS-5 sample reached 33.81mmol·h^-1·g^-1,which is 4.66 times the hydrogen production rate of the ZCS sample.The cycle experiment proved that the sample has excellent stability.The hydrogen production rate of ZCS-5 sample can still reach 28.90 mmol·h^-1·g^-1,which is 85.5%of the reaction rate of the sample before the cycle.Through a series of characterization and analysis,it was determined that Ni²⁺is highly dispersed in the system.While improving the stability,it also inhibits the recombination of photogenerated carriers to a certain extent,and provides more reactive sites,which is more conducive to light.The catalytic water splitting reaction proceeds.Secondly,a two-step hydrothermal method was used to synthesize a photocatalyst with a Zn_xCd_1-xS nanotube structure.The Zn S-DETA precursor was synthesized first,and then nanotube catalysts with different Cd²⁺content were hydrothermally synthesized again,and the photocatalytic decomposition of water Hydrogen production performance test,and cycle stability experiment for the best active sample to determine the best Zn:Cd=2:1,the sample has excellent stability,at this time the hydrogen production rate is 8.48 mmol·h-1·g-1,which is 3.9times the hydrogen production rate of the Cd S sample,and a series of analysis and characterization were carried out to analyze the reason for the best activity and propose a possible photocatalytic mechanism.At the end of the thesis,a summary of the results of the work was carried out,and combined with the problems faced by the current photocatalytic technology direction,the future development direction was prospected.