Enhancements on oxygen vacancy and light absorption of alkaline-etched BiVO4 for photoelectrochemical water oxidation.

Designing the favorable morphology with large surface area and abundant oxygen vacancies for BiVO 4 can enhance its electron diffusion lengths and improve its photocatalytic ability toward photoelectrochemical water oxidation. The ex-situ alkaline etching process is reported to be facile for enhancing the light absorption and oxygen vacancy of BiVO 4 , but the systematic study of alkaline etching on the photocatalytic ability of BiVO 4 is rare. In this study, alkaline-etched BiVO 4 is firstly fabricated using a hydrothermal process with different durations as the photocatalyst of water oxidation. The BiVO 4 etched by alkaline for longer durations presents rougher surface, more oxygen vacancies and higher light absorption. The larger carrier densities and the smaller charge-transfer resistances are also achieved for the alkaline etched BiVO 4. The largest photocurrent density of 2.38 mA/cm2 is achieved at 1.23 V versus reversible hydrogen electrode in the Na 2 SO 4 electrolyte for BiVO 4 etched by alkaline for 45 min, while the pristine BiVO 4 electrode only shows a photocurrent density of 0.59 mA/cm2. The photocurrent retention of 81% is also obtained for the alkaline etched BiVO 4 electrode after continuous illumination for 6000 s. The results imply the feasibility of applying the alkaline etching process on refining the photoelectrochemical catalytic ability of BiVO 4. [Display omitted] • Alkaline-etched BiVO 4 is fabricated by hydrothermal process in various durations. • Etching BiVO 4 with longer time shows rougher surface and more oxygen vacancies. • Photocurrent density of 2.38 mA/cm2 is got at 1.23 V RHE for optimal etched BiVO 4. • It is due to large carrier densities and smaller charge-transfer resistances. • Photocurrent retention of 81% is got after continuous illumination for 6000 s. [ABSTRACT FROM AUTHOR]