Enriched Surface Oxygen Vacancies of Photoanodes by Photoetching with Enhanced Charge Separation

Abstract A facile photoetching approach is described that alleviates the negative effects from bulk defects by confining the oxygen vacancy (O vac ) at the surface of BiVO 4 photoanode, by 10‐minute photoetching. This strategy could induce enriched O vac at the surface of BiVO 4 , which avoids the formation of excessive bulk defects. A mechanism is proposed to explain the enhanced charge separation at the BiVO 4 /electrolyte interface, which is supported by density functional theory (DFT) calculations. The optimized BiVO 4 with enriched surface O vac presents the highest photocurrent among undoped BiVO 4 photoanodes. Upon loading FeOOH/NiOOH cocatalysts, photoetched BiVO 4 photoanode reaches a considerable water oxidation photocurrent of 3.0 mA cm −2 at 0.6 V vs. reversible hydrogen electrode. An unbiased solar‐to‐hydrogen conversion efficiency of 3.5 % is realized by this BiVO 4 photoanode and a Si photocathode under 1 sun illumination.