Surface Reconstruction and Passivation of BiVO 4 Photoanodes Depending on the "Structure Breaker" Cs .

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.