A oxygen vacancy-modulated homojunction structural CuBi2O4photocathodes for efficient solar water reduction

The photoelectrochemical (PEC) water reduction performance of CuBi2O4(CBO)-based photocathodes is still far from their theoretical values due to low bulk and surface charge separation efficiencies. Herein, we propose a regrowth strategy to prepare a photocathode with CBO coating on Zn-doped CBO (CBO/Zn-CBO). Furthermore, NaBH(4)treatment of CBO/Zn-CBO introduced oxygen vacancies (O-v) on CBO/Zn-CBO. It was found that Zn-doping not only increases the charge carrier concentration of CBO, but also leads to appropriate band alignment to form homojunctions. This homojunction can effectively promote the separation of electron-hole pairs, thus obtaining excellent photocurrent density (0.5 mA cm(-2)at 0.3 Vvs.RHE) and charge separation efficiency (1.5 times than CBO). The following surface treatment induced O(v)on CBO/Zn-CBO, which significantly increased the active area of the surface catalytic reaction and further enhanced the photocurrent density (0.6 mA cm(-2)). In the absence of cocatalysts, the electron injection efficiency of O-v/CBO/Zn-CBO was 1.47 times improved than that of CBO. This work demonstrates a homojunction photocathode with O(v)modulation, which provides a new view for future photoelectrochemical water splitting.