Research on the Influence of the Interfacial Properties Between a Cu BiS Film and an In Cd S Buffer Layer for Photoelectrochemical Water Splitting

The ternary compound photovoltaic semiconductor Cu BiS thin film-based photoelectrode demonstrates a quite promising potential for photoelectrochemical hydrogen evolution. The presented high onset potential of 0.9 V attracts much attention and shows that the Cu BiS thin films are quite good as an efficient solar water splitting photoelectrode. However, the CdS buffer does not fit the Cu BiS thin film: the conduction band offset between CdS and Cu BiS reaches 0.7 eV, and such a high conduction band offset (CBO) significantly increases the interfacial recombination ratio and is the main reason for the relatively low photocurrent of the Cu BiS /CdS photoelectrode. In this study, the In Cd S buffer layer is found to be significantly lowered the CBO of CBS/buffer and that the In incorporation ratio of the buffer influences the CBO value of the CBS/buffer. The Pt-TiO /In Cd S/Cu BiS photocathode exhibits an appreciable photocurrent density of ≈12.20 mA cm at 0 V with onset potential of more than 0.9 V , and the ABPE of the Cu BiS -based photocathode reaches the highest value of 3.13%. By application of the In Cd S buffer, the Cu BiS -BiVO tandem cell presents a stable and excellent unbiased STH of 2.57% for over 100 h.