Improving PEC Performance of BiVO4 by Introducing Bulk Oxygen Vacancies by He+ Ion Irradiation

Bismuth vanadate is a promising semiconductor in photoelectrochemical (PEC) water oxidation due to its suitable band gap (similar to 2.4 eV) for absorption of solar spectrum. Nevertheless, low charge mobility and poor photogenerated carrier separation efficiency of BiVO4 lead to unsatisfactory photocurrent densities and poor PEC performance. Here, we report an innovative method of introducing bulk oxygen vacancies into BiVO4 film through helium ion irradiation to improve the transfer and separation efficiency by improving the bulk conductivity. The result indicates that the highest photocurrent density of the ion-irradiated BiVO4 reaches 1.33 mA cm(-2) at 1.2 V vs RHE, which is about 70% higher than that of the un-irradiated one (similar to 0.77 mA cm-2 ). The corresponding highest IPCE reaches 40% around 400 nm, which is double compared with that of the un-irradiated BiVO4. Therefore, ion irradiation is an effective and precise method to improve the photoelectrochemical performance by inducing bulk oxygen vacancies into BiVO4. It can also be extended to other photoelectrode materials.