Prompt Hole Extraction Suppresses V⁵⁺ Dissolution and Sustains Large-Area BiVO₄ Photoanodes for Over 2100 h Water Oxidation.

Abstract

Nanostructured bismuth vanadate (BiVO₄) 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 V⁵⁺ dissolution limits the long-term stability of BiVO₄. Herein, guided by DFT calculations, we introduce an ALD-derived NiO_<i>x</i> catalyst layer on BiVO₄ to stabilize the surface Bi-O bonds, facilitate hole extraction, and thus suppress the V⁵⁺ dissolution. At the same time, the ALD NiO_<i>x</i> 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 BiVO₄ to 2.05%, as well as a fill factor of 47.1%. By adding trace NaVO₃ to the electrolyte, the NiO_<i>x</i>/BiVO₄ photoanode with an illumination area of 10.5 cm² shows a record operational stability of more than 2100 h.