The Optimization Of CdS Buffer Layer Of CZTS Photocathode And Its Effect On Photoelectrochemical Water Splitting Performance

Photoelectrochemical water splitting is an effective method for the direct conversion of solar energy into chemical energy,and how to utilize photochemical water splitting to produce hydrogen efficiently is the focus of attention.Cu₂ZnSnS₄?CZTS?photocathode,due to high light absorption coefficient(>10⁴ cm^-1),rich element content and suitable energy band structure,has attracted extensive attention in the field of photoelectrochemical water splitting.However,the poor electrical and optical properties of the CdS buffer layer in the photocathode of CZTS/CdS heterostructure,as well as the interface quality and charge recombination of the CZTS/CdS heterostructure limit the further improvement of the photoelectrochemical water splitting performance of CZTS.In view of the above problems,this paper has carried out research work on the photoelectric performance of CdS buffer layer and the property improvement of CZTS/CdS interface,and obtained certain research results.Specific research contents are as follows:?1?to solve the problem of poor optical and electrical properties of CdS layer,we introduced In ion into the process of CBD deposition CdS,and prepared the In ion-doped CZTS/CdS:In photocathode.The effects of In ion doping on the photoelectrochemical water splitting performance of CZTS photocathode were investigated systematically.The study shows that the introduction of In ion can effectively increase the carrier concentration of CdS layer,while improving the CdS absorption range of visible light and improving the utilization rate of CZTS electrode to visible light,thus promoting the separation and transmission of charge at interface and buffer layer.When the In ion doping concentration was 3%,the photocathode reached the optimal photocurrent density value.Under the voltage of 0 V vs.RHE,the photocurrent density was nearly twice as high as that of CZTS/CdS electrode without doping In ion(from 1.1 mA cm^-22 to 2.2 mA cm^-2),showing significantly improved photoelectrochemical water splitting performance.?2?to solve the problem of charge recombination at CZTS/CdS interface,we improved the preparation process of CdS layer and modified CdS buffer layer on the CZTS surface by using two-step deposition CdS method.The effect of heat treatment temperature after the first step of depositing CdS on the photoelectrochemical water splitting performance of CZTS photocathode was investigated.By comparing with traditional deposition CdS method and one-step deposition CdS combined heat treatment samples,it is found that two-step deposition CdS method can effectively improve the interface quality of CZTS/CdS and reduce the electrode shunting paths.Under the voltage of 0 V vs.RHE,the photocurrent density of the electrode reaches 2.8 mA cm^-2,which is 100%and 84%higher than that of the conventional one-step method and one-step CdS deposition combined heat treatment method,respectively.And it showed excellent photoelectrochemical water splitting performance.