Engineering oxygen defects on Bi2WO6 to facilitate photoelectrocatalytic water splitting

Oxygen vacancies play a crucial role in modulating the chemical and physical properties of metal oxides, significantly impacting semiconductor conductivity and facilitating the dissociation and transportation of photoinduced charge carriers. In this study, Bi₂WO₆ films were treated with NaBH₄ solutions of varying concentrations to effectively introduce oxygen vacancies. The presence and effects of oxygen vacancies was examined from the perspectives of crystal structure by using XRD refinement and energy band structure diagram based on the density functional theory (DFT) calculation. In the photoelectrochemical water oxidation process, the optimized sample exhibited a more negative onset potential compared to pristine Bi₂WO₆ and exhibited a photocurrent density of 0.015 mA cm⁻²(vs. RHE), which is about 5-fold higher than that of the pristine material (0.076 mA cm⁻²). This study provides a simple and effective approach to engineering Bi₂WO₆ electrodes, thereby enhancing the efficiency of photoelectrochemical water splitting.