Chalcopyrite CuGaSe₂ thin film for photoelectrochemical water splitting into hydrogen

Abstract

Copper chalcopyrite compound CuGaSe₂ (CGS) is a promising material for its application to photoelectrochemical (PEC) water splitting into H₂. In this article, we firstly review operating principle and measurement methods of PEC water splitting by using semiconductor-based electrodes. Then, studies on PEC H₂ evolution over the CGS-based photocathodes were reviewed. For realizing efficient PEC H₂ evolution, surface modifications with a CdS layer and nanoparticulate Pt catalytis were indispensable. Moreover, insertion of a Cu-deficient layer and its further modification with Rb are found to be effective for improvements of PEC properties. Since present photoelectrodes have poor resistances under an operating bias, further functionalization is required to improve the long-term durability for practical uses.