Prompt Hole Extraction Suppresses V 5+ Dissolution and Sustains Large-Area BiVO 4 Photoanodes for Over 2100 h Water Oxidation.

Nanostructured bismuth vanadate (BiVO 4 ) is at the forefront of emerging photoanodes in photoelectrochemical tandem devices for solar water splitting owing to the suitable band edge position and efficient charge separation capability. However, the (photo)chemical corrosion involving V 5+ dissolution limits the long-term stability of BiVO 4 . Herein, guided by DFT calculations, we introduce an ALD-derived NiO x catalyst layer on BiVO 4 to stabilize the surface Bi-O bonds, facilitate hole extraction, and thus suppress the V 5+ dissolution. At the same time, the ALD NiO x catalyst layer could efficiently suppress the surface recombination and accelerate the surface OER kinetics, boosting the half-cell applied bias photon-to-current efficiency of BiVO 4 to 2.05%, as well as a fill factor of 47.1%. By adding trace NaVO 3 to the electrolyte, the NiO x /BiVO 4 photoanode with an illumination area of 10.5 cm 2 shows a record operational stability of more than 2100 h.