Chalcopyrite CuGaSe₂ thin film for photoelectrochemical water splitting into hydrogen

Abstract

A copper chalcopyrite compound CuGaSe₂ (CGS) thin film is a promising material for application to photoelectrochemical (PEC) water splitting into hydrogen (H₂). In this article, we first review the operating principle and measurement methods of PEC water splitting using semiconductor-based electrodes before reviewing studies on PEC H₂ evolution over CGS-based photocathodes. The requirements of surface modifications of the CGS thin film with a CdS layer and nanoparticulate Pt catalysts for realizing efficient PEC H₂ evolution are then introduced. Moreover, the effects of insertion of a Cu-deficient layer between the CGS film and the CdS layer and doping of Rb components into the CGS film for improving PEC properties are discussed. Finally, a critical problem of current CGS-based PEC devices for their practical applications, i.e., poor disabilities under an operating bias, is discussed.