Interfacial regulation of photoanodes for photoelectrochemical water splitting: the roles of the interlayer and overlayer

Abstract

Green hydrogen plays a pivotal role in the construction of a sustainable energy system. Photoelectrochemical (PEC) water splitting has theoretically high efficiency for solar energy conversion and promises zero pollution in the hydrogen production process. However, its efficiency in industrial applications and stability during long-term operation still limit the pace of development. The design of efficient and stable photoelectrodes requires careful synergistic regulation of multiple interlayers and overlayers. This review presents the key roles of interlayers or overlayers in the field of PEC water splitting, particularly in photoanode modification. First, the effect of interface states on photoelectrodes is emphasized, highlighting the significance of interface state passivation in minimizing surface recombination and maximizing charge separation. Subsequently, the various roles played by interlayers and overlayer in improving the overall performance of photoanodes are classified and elaborated. These include passivation of interface states to enhance charge separation efficiency, regulation of charge transport mechanisms across interlayers, and construction of hole storage layers, serving as protective layers and acting as catalyst layers. Finally, this review points out the challenges and perspectives for future development of interlayers in PEC water splitting.