Abstract
Direct photoelectrochemical 2-electron water oxidation to renewable H(2) O(2) production on an anode increases the value of solar water splitting. BiVO(4) has a theoretical thermodynamic activity trend toward highly selective water oxidation H(2) O(2) formation, but the challenges of competing 4-electron O(2) evolution and H(2) O(2) decomposition reaction need to overcome. The influence of surface microenvironment has never been considered as a possible activity loss factor in the BiVO(4) -based system. Herein, it is theoretically and experimentally demonstrated that the situ confined O(2) , where coating BiVO(4) with hydrophobic polymers, can regulate the thermodynamic activity aiming for water oxidation H(2) O(2) . Also, the hydrophobicity is responsible for the H(2) O(2) production and decomposition process kinetically. Therefore, after the addition of hydrophobic polytetrafluoroethylene on BiVO(4) surface, it achieves an average Faradaic efficiency (FE) of 81.6% in a wide applied bias region (0.6-2.1 V vs RHE) with the best FE of 85%, which is 4-time higher than BiVO(4) photoanode. The accumulated H(2) O(2) concentration can reach 150 µm at 1.23 V versus RHE under AM 1.5 illumination in 2 h. This concept of modifying the catalyst surface microenvironment via stable polymers provides a new approach to tune the multiple-electrons competitive reactions in aqueous solution.