Unveiling the activity and stability of BiVO4 photoanodes with cocatalyst for water oxidation

Developing low-cost and efficient cocatalyst is highly desirable for photoelectrochemical (PEC) water oxidation. FeOOH is one of the most typical cocatalysts, the active sites of FeOOH in PEC remain unclear. Herein, the FeOOH was deposited on BiVO4 photoanodes through electrodeposition. A series of experimental evidence shows that the Bi-O-Fe bond is beneficial to the improvement of water oxidation activity, while the FeOOH can not restrain the dissolution of V5+ and improve the stability of the photoelectrode. In order to further improve the activity and stability of BiVO4/FeOOH photoanode, a low-cost metal-organic coordination composed of tannic acid coordinated with Ni ions (TANi) was assembled on the BiVO4/FeOOH (denoted as BiVO4/FeOOH/TANi). Under AM 1.5 G illumination, an impressive current density of 4.6 mA cm-2 (1.23 V vs. RHE) was obtained for BiVO4/FeOOH/TANi photoanode. Systematic studies reveal that the enhanced PEC activity comes from the protection of BiVO4 and enhancement of charge separation efficiency. This work provides a strategy for designing cocatalysts to construct efficient and stable PEC water oxidation.

Automated summary

This study deposited FeOOH onto BiVO4 photoanodes through electrodeposition and found that the Bi-O-Fe bond is beneficial for improving the water oxidation activity of the catalyst. However, FeOOH cannot restrain the dissolution of V5+ and improve the stability of the photoelectrode. By assembling a low-cost metal-organic coordination of tannic acid coordinated with Ni ions, the activity and stability of the BiVO4/FeOOH photoanode were further enhanced.