Multi-strategy preparation of BiVO4 photoanode with abundant oxygen vacancies for efficient water oxidation

Abstract

The water oxidation reaction, as a half-reaction in photoelectrochemistry (PEC) water splitting, has long been hindered due to its slow kinetics. Creating oxygen vacancies (Ov) has attracted considerable attention as an effective method to improve the conductivity and facilitate the surface reaction of photoelectronic materials to improve their PEC performance. Therefore, the preparation of suitable photoanodes with oxygen vacancies becomes a critical part in the development of PEC water splitting. Herein, we designed a novel synthetic strategy involving In doping, photo-potentiostatic polarization and co-catalyst deposition, to induce massive oxygen vacancies in BiVO4 photoanode for efficient PEC water oxidation. The prepared FeOOH/In-BiVO4(L) photoanode exhibits an outstanding photocurrent density of 5.02 mA cm−2 at 1.23 VRHE, which improved 2.7 times compared to those of pristine BiVO4 photoanode (1.84 mA cm−2). By experimental and mechanism exploration, there generated a large number of oxygen vacancies on the BiVO4 photoanode surface after doping and polarization strategies, which is beneficial to increasing the conductivity and charge separation. Besides, FeOOH co-catalyst is deposited to provide more abundant active sites for the water oxidation reaction. This work demonstrates that In doping and photo-potentiostatic polarization strategies can optimize BiVO4 photoanode to construct highly efficient and stable PEC water splitting devices.