Towards Long‐Term Photostability of Nickel Hydroxide/BiVO₄ Photoanodes for Oxygen Evolution Catalysts via In Situ Catalyst Tuning

Abstract

Abstract Increasing long‐term photostability of BiVO 4 photoelectrode is an important issue for solar water splitting. The NiOOH oxygen evolution catalyst (OEC) has fast water oxidation kinetics compared to the FeOOH OEC. However, it generally shows a lower photoresponse and poor stability because of the more substantial interface recombination at the NiOOH/BiVO 4 junction. Herein, we utilize a plasma etching approach to reduce both interface/surface recombination at NiOOH/BiVO 4 and NiOOH/electrolyte junctions. Further, adding Fe 2+ into the borate buffer electrolyte alleviates the active but unstable character of etched‐NiOOH/BiVO 4 , leading to an outstanding oxygen evolution over 200 h. The improved charge transfer and photostability can be attributed to the active defects and a mixture of NiOOH/NiO/Ni in OEC induced by plasma etching. Metallic Ni acts as the ion source for the in situ generation of the NiFe OEC over long‐term durability.