Enhanced photoelectrochemical water oxidation performance by altering the interfacial charge transfer path

Abstract

Herein, a cocatalyst was extensively used to enhance the photocatalytic water oxidation performance. In a cocatalyst/semiconductor system, charge transfer between a semiconductor and cocatalyst is a crucial process for the photoelectrochemical (PEC) water oxidation performance; however, the influence of surface states on charge transfer has rarely been discussed. In this study, Al₂O₃ was inserted into the CoPi/Ti-Fe₂O₃ interface to fabricate a CoPi/Al₂O₃/Ti-Fe₂O₃ photoanode. CoPi/Al₂O₃/Ti-Fe₂O₃ showed a notable improvement in the photocurrent density. A combination of UV–vis diffuse reflectance spectroscopy (DRS), surface photovoltage spectroscopy (SPS), chopped light photocurrent, and photocurrents under different chopped light frequencies was used to study the real role of Al₂O₃ in the charge transfer process. It was found that Al₂O₃ passivated the surface states of Ti-doped Fe₂O₃, leading to a better interfacial charge transfer between Ti-doped Fe₂O₃ and CoPi, resulting in the enhanced PEC water oxidation performance.