Fast annealing fabrication of porous CuWO₄ photoanode for charge transport in photoelectrochemical water oxidation

Abstract

Ternary-phase CuWO4 oxide with an electronic band gap of 2.2–2.4 eV is a potential candidate photoanode material for photoelectrochemical (PEC) water splitting. Herein, we present an efficient method to prepare CuWO4 film photoanode by combining hydrothermal method and hybrid microwave annealing (HMA) process. In comparison with conventional thermal annealing (CTA), HMA can achieve CuWO4 thin film within minutes by using SiC susceptor. When the CuWO4 photoanode is prepared by HMA, its PEC water oxidation performance improves from 0.21 to 0.29 mA cm−2 at 1.23 VRHE comparing with the one prepared by CTA. The origin of the enhanced photocurrent was investigated by means of complementary physical characterizations and PEC methods. The results demonstrated that the obtained HMA processed CuWO4 photoanode not only exhibited intrinsic porous nanostructures but also abundant surface hydroxyl groups, which facilitated sufficient mass transport and the charge transfer. Our results highlight the application of HMA for the fast fabrication of porous film photo-electrodes without using sacrificial template.