Insight of water oxidation kinetics of BiVO₄ photoanode by vapor phase cation exchange method

Among numerous semiconductors, BiVO₄ has a suitable bandgap width, excellent valence band energy level and high activity for visible light water oxidation. It is an important oxygen evolution photocatalyst, but its carrier migration rate is still lower than other semiconductor materials. Therefore, in this paper, transition metal cations such as Fe³⁺ were selectively exchanged with V⁵⁺ in BiVO₄ in a high-temperature Ar atmosphere by vapor phase cation exchange method, cationic bonds with strong binding force were formed at the interface between metal elements and catalysts, effectively accelerating bulk to surface charge separation. The adsorption energy and surface oxidation kinetics of the intermediate in the process of water oxidation were enhanced, and the photoelectrochemical properties of the intermediate were effectively improved.

The vapor phase cation exchange between Fe³⁺ and V⁵⁺ of BiVO₄ photoanode makes the metal element and the catalyst form a strong cationic bond at the interface, which greatly reduces the charge transport resistance to a certain extent, accelerates the water reaction kinetics, which can not only significantly improve the stability, but also increase the photocurrent density and significantly reduce the starting potential.