Activity and stability boosting of BiVO4 photoanode by NH2-MIL-125 and NiFeOx cooperative modification for water oxidation

The development of low-cost, ultra-stable catalysts for efficient oxygen evolution reactions (OER) is ideal for photoelectrochemical (PEC) water splitting. However, the severe charge recombination and slow kinetic reaction hinder the process of OER. Herein, we demonstrated the cooperative modification between Ti-MOF (NH2-MIL- 125) and NiFeOx for significantly enhancing the oxygen evolution activity of BiVO4 photoanodes, and the optimal photocurrent density has been reached to 3.92 mA cm- 2 at 1.23 V (vs. reversible hydrogen electrode (RHE), AM 1.5 G). The integrated BiVO4/NH2-MIL-125/ NiFeOx photoanode system exhibits an applied bias photon-to-current efficiency (ABPE) of 2 % at 0.77 V RHE . More importantly, the photostablitily was significantly prolonged with a photocurrent retention rate of 92 % upon 20 h testing. The excellent performance is attributed to the construction of BiVO4/NH2-MIL-125 heterojunction, which improves the separation efficiency of photo- generated electron-hole pairs and the bimetallic NiFeOx co-catalyst reduces the surface reaction energy barrier. This work provides an effective approach for collaborative modification to improve the performance and stability of BiVO4 photoanode PEC water splitting systems.