Fabrication of Cu2ZnSnS4 (CZTS) by co-electrodeposition of Cu-Zn-Sn alloys, and effect of chemical composition of CZTS on their photoelectrochemical water splitting

Cu-Zn-Sn (CZT) alloy was fabricated by environmentally friendly co-electrodeposition method. The CZTS formed by the sulfurization of the CZT alloy effectively worked for the PEC water splitting, producing H2 under sunlight irradiation. [Display omitted] •Cu-Zn-Sn (CZT) alloys were fabricated by co-electrodeposition method.•The CZT was sulfurized in the presence of S to form Cu2ZnSnS4 (CZTS).•Chemical composition of CZTS influences to PEC properties.•Pt-In2S3/CZTS exhibited high H2 evolution from PEC H2O splitting.•Sn-rich CZTS with small amount of SnO2 enhanced the electron transfer. Sulfide kesterite Cu2ZnSnS4 (CZTS), an intrinsic p-type semiconductor, provides an attractive low-cost, environmentally friendly photoelectrochemical (PEC) water splitting to evolve hydrogen. The purpose of this study was to clarify the effect of the chemical composition of CZTS on the PEC properties and the correlation with their structures. The CZTS was fabricated on a Mo/glass by a non-vacuum process, i.e., co-electrodeposition (co-ED) of Cu-Zn-Sn (CZT) alloys, followed by sulfurization with solid sulfur. To optimize the chemical composition of CZTS, the bath concentrations, applied potentials and amounts of electric charge for preparation conditions of the CZT precursors were examined. The CZTS with Cu-poor and Sn-rich composition compared with stoichiometry was found to exhibit relatively effective PEC water splitting. It was suggested that the high PEC performance was attributed to efficient charge carrier transport due to the presence of a small amount of SnO2 phase on the CZTS surface.