Killing two birds with one stone: Enhancing the photoelectrochemical water splitting activity and stability of BiVO4 by Fe ions association

BiVO4 is a promising semiconducting photoanode for photoelectrochemical (PEC) water splitting due to its suitable bandgap. However, the dissolution of V5+ and sluggish reaction kinetics at the surface in the oxygen evolution reaction (OER) limit its applications. Herein, we report a convenient strategy to change the microenvironment by adding Fe(Ⅲ) into the electrolyte. During the PEC process, Fe(Ⅲ) ions not only improve the current density, but also show excellent stability of BiVO4. Consequently, the current increases by more than 1.7 times compared to that without Fe(III). Photoelectrochemical, morphological, and structural characterizations reveal that the FeOOH co-catalyst produced in situ on the BiVO4 photoanode by cyclical formation of the intermediates at the electrode/electrolyte interface during OER accelerates the OER kinetics and prevents photo-corrosion by suppressing the dissolution of V5+. The results reveal a new strategy for the multifunctional modification of photoanodes for efficient solar conversion.