Study On Preparation Of CuInS₂ Thin Films And The Photoelectrocatalytic Performance

Massive emissions of CO₂ has seriously affected human life and ecological environment, while CO₂ is a cheap, non-toxic, rich chemical raw materials. This paper explored the conversion of CO₂ to methanol by photoelectric catalytic method with low energy consumption. In this paper,CuInS₂ semiconductor was used as light absorbing material. The relationship between the structure of CuInS₂ thin films and the photoelectrocatalytic performance was discussed.In this study, CuInS₂ thin films were prepared by spin coating method and photoelectrocatalytic reduction of CO₂ was carried out. The influence of the structure of the obtained films at different annealing temperatures on the photoelectrocatalytic performance was analyzed. The optimum temperature was 430℃. The catalytic performance of the films with different precursors ratios was analyzed. The optimum Cu/In/S was 1/0.72/4.05. The relationship between the speed of catalytic reaction and reaction time was analyzed. The reaction rate of 0 to 1.5h was faster than that of 1.5 to 4.5h.The XRD, Raman and XPS characterization of the films obtained by different precursors ratios were analyzed. It was found that the films with different ratios contained CuS heterogeneous phases. The CuO phase also appears when the content of indium in the precursor increases. The photoelectrocatalytic performance of CuInS₂ thin films containing CuS and CuO phase is stronger than that of CuS alone. The Raman and XPS patterns of the films before and after reaction were analyzed. It is concluded that the CuS decreases or disappears after the reaction, and the CuO increases, that is, CuS is converted to CuO. By analyzing Raman and XPS characterization at different reaction times, it was concluded that the CuInS₂ films containing only CuS heterogeneous phase had stronger photocatalytic performance than CuO.By analyzing the fluorescence emission spectra of films with different precursors ratios, the intensity peaks of CuInS₂ thin films containing CuS and CuO phases are weaker than those containing only CuS phases. The results show that the the electron-hole separation efficiency in CuInS₂ thin films containing CuS and CuO is improved. The improvement of electron-hole separation efficiency can improve the photoelectrocatalytic efficiency of the films.