Surface Reconstruction and Passivation of BiVO(4) Photoanodes Depending on the “Structure Breaker” Cs(+)

[Image: see text] Monoclinic BiVO(4) is one of the most promising photoanode materials for solar water splitting. The photoelectrochemical performance of a BiVO(4) photoanode could be significantly influenced by the noncovalent interactions of redox-inert metal cations at the photoanode–electrolyte interfaces, but this point has not been well investigated. In this work, we studied the Cs(+)-dependent surface reconstruction and passivation of BiVO(4) photoanodes. Owing to the “structure breaker” nature of Cs(+), the Cs(+) at the BiVO(4) photoanode–electrolyte interfaces participated in BiVO(4) surface photocorrosion to form a Cs(+)-doped bismuth vanadium oxide amorphous thin layer, which inhibited the continuous photocorrosion of BiVO(4) and promoted surface charge transfer and water oxidation. The resulting cocatalyst-free BiVO(4) photoanodes achieved 3.3 mA cm(–2) photocurrent for water oxidation. With the modification of FeOOH catalysts, the photocurrent at 1.23 V(RHE) reached 5.1 mA cm(–2), and a steady photocurrent of 3.0 mA cm(–2) at 0.8 V(RHE) was maintained for 30 h. This work provides new insights into the understanding of Cs(+) chemistry and the effects of redox-inert cations at the electrode–electrolyte interfaces.