Recent Advances in CuInS₂-Based Photocathodes for Photoelectrochemical H₂ Evolution

Photoelectrochemical (PEC) H₂ production from water using solar energy is an ideal and environmentally friendly process. CuInS₂ is a p-type semiconductor that offers many advantages for PEC H₂ production. Therefore, this review summarizes studies on CuInS₂-based PEC cells designed for H₂ production. The theoretical background of PEC H₂ evolution and properties of the CuInS₂ semiconductor are initially explored. Subsequently, certain important strategies that have been executed to improve the activity and charge-separation characteristics of CuInS₂ photoelectrodes are examined; these include CuInS₂ synthesis methods, nanostructure development, heterojunction construction, and cocatalyst design. This review helps enhance the understanding of state-of-the-art CuInS₂-based photocathodes to enable the development of superior equivalents for efficient PEC H₂ production.