Oxygen vacancies activating surface reactivity to favor charge separation and transfer in nanoporous BiVO4 photoanodes

• Surface reactivity activation was induced in favor of cooperation with photoactivity. • Oxygen vacancies were demonstrated to activate WOR with high charge separation. • A record photocurrent of 4.32 mA cm −2 at 1.23 V RHE was achieved for single BVO. • Surface activation stays competitive with cocatalyst integration for PEC technology. The sluggish catalytic reactivity on the surface of most semiconductors is a common obstacle in developing photo-electrochemical (PEC) electrodes. Loading cocatalysts becomes a plausible scenario but remains challenging in the integration with semiconductors due to the complicated interfacial issues. This work introduces an feasible strategy of activating surface reactivity, alternative to cocatalysis, in cooperating with semiconductor photoactivity to boost PEC performance. We apply an ionized argon plasma technology on three-dimensional (3D) nanoporous BiVO 4 (BVO) to controllably generate surface oxygen vacancies, which enable surface activation favoring charge separation and transfer towards water oxidation reaction (WOR). A remarkable photocurrent density of 4.32 mA cm −2 is achieved at 1.23 V versus reversible hydrogen electrode (RHE) under AM 1.5 G illumination, which is a record among the reported single BVO photoanodes and even surpasses the performances of most cocatalyst-assisted ones. This study provides an alternative solution to sluggish catalytic kinetics on semiconductor photoelectrodes, thus paving a novel avenue to modulate cooperation with photoactivity in PEC technology.