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 (∼2.4 eV) for absorption of solar spectrum. Nevertheless, low charge mobility and poor photogenerated carrier separation efficiency of BiVO 4 lead to unsatisfactory photocurrent densities and poor PEC performance. Here, we report an innovative method of introducing bulk oxygen vacancies into BiVO 4 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 BiVO 4 reaches 1.33 mA cm –2 at 1.2 V vs RHE, which is about 70% higher than that of the un-irradiated one (∼0.77 mA cm –2 ). The corresponding highest IPCE reaches 40% around 400 nm, which is double compared with that of the un-irradiated BiVO 4 . Therefore, ion irradiation is an effective and precise method to improve the photoelectrochemical performance by inducing bulk oxygen vacancies into BiVO 4 . It can also be extended to other photoelectrode materials.