Boost proton transfer in water oxidation by constructing local electric fields on BiVO4 photoanodes

The slow-proton-fast-electron process severely limits the catalytic efficiency of oxygen evolution reaction. A method is proposed to accelerate proton transfer by building up local electric fields. Modifying acetic, ethanedioic and propanetricarboxylic (C 6 H 8 O 6 ) ligands on BiVO 4 surface results in a potential difference between BiVO 4 and ligands that generates a local electric field which serves as a driving force for proton transfer. Among the ligands, carrying the strongest electron-withdrawing ability, the modification of C 6 H 8 O 6 forms the strongest local electric field and leads to the fastest proton transfer and the smallest thermodynamic overpotential. C 6 H 8 O 6 -BiVO 4 exhibits 3.5 times photocurrent density as high as that of pure BiVO 4 , which is 3.50 mA cm –2 at 1.23 V RHE . The onset potential of C 6 H 8 O 6 -BiVO 4 shifts negatively from 0.70 to 0.38 V RHE . The mechanism for OER transitions from thermodynamically high energy proton-coupled electron transfer to thermodynamically low energy electron transfer as proton transfer is accelerated.