Preparation And Photocatalytic Performance Of Zn_0.5Cd_0.5S Based Photocatalysts

Photocatalysis was a clean technology that converted solar energy into chemical energy,and it was considered to be one of the most promising environmental protection technologies in response to energy crises and environmental pollution in the future.Transition metal sulfides developed rapidly in the field of photocatalysis due to wide sources,low prices and good light absorption capacity.Among them,Zn_0.5Cd_0.5S solid solution was payed wide attention on the aspect of photocatalytic hydrogen production because of the suitable energy band gap,low reduction potential and good photocorrosion resistance.However,limited by the recombination rate of photo-generated carriers and severe particle agglomeration,the hydrogen production performance of Zn_0.5Cd_0.5S solid solution was not ideal.Based on this,this paper took Zn_0.5Cd_0.5S as the basic research object,and intended to improve its photocatalytic hydrogen production performance through a series of measures such as homogeneous structure construction,loading co-catalyst,and doping ion.The main work was as follows:（1）The cubic/hexagonal Zn_0.5Cd_0.5S homogeneous structure was successfully synthesized by a two-step method.The photocatalytic hydrogen production performance and photocatalytic promotion mechanism were explored to determine its optimal compound ratio.The results showed that the construction of a homogenous structure greatly improved photocatalytic hydrogen production performance.When the hexagonal phase Zn_0.5Cd_0.5S was added at 15%（15%H）,the photocatalytic hydrogen production rate could be as high as 5.9 mmol/g/h.The results of photoelectrochemical analysis showed that the effective separation of photogenerated carriers in the homogeneous structure was the main reason for the improvement of its photocatalytic performance.（2）The Zn_0.5Cd_0.5S/Ti₃C₂composites was constructed by in-situ growth method with high conductivity Ti₃C₂as co-catalyst,research its photocatalytic activity and explore its photocatalytic activity promotion mechanism.The results showed that the prepared composite materials showed excellent performance of photocatalytic hydrogen production.Especially,the hydrogen production rate of 20%TC samples was as high as 10.8 mmol/g/h,which was about 7.5 times that of Zn_0.5Cd_0.5S.At the same time,20%TC also had good photocatalytic degradation of methyl orange（MO）performance.The photoelectrochemical analysis results showed that the strong coupling between Ti₃C₂and Zn_0.5Cd_0.5S could accelerate the transfer of carriers to the metal Ti₃C₂,thereby inhibiting the recombination of electrons and holes,and improving the photocatalytic performance of Zn_0.5Cd_0.5S.（3）The Mo-doped Zn_0.5Cd_0.5S photocatalytic material was prepared by a one-step hydrothermal method,and the influence of the introduction of Mo on the catalyst activity was explored.The results displayed that the photocatalytic activity of the doped material was significantly higher than that of pure Zn_0.5Cd_0.5S,and the maximum photocatalytic hydrogen production rate was 9.0 mmol/g/h.The optimal doping ratio is determined to be 1.5%and 1.5%.The degradation rate of Mo to TC can reach 99.6%within 30 min.The enhancement of photocatalytic performance was mainly attributed to the impurity level generated by the introduction of Mo element,which promoted the transport of carriers and improved the light absorption capacity.