Activity and Stability Boosting of an Oxygen-Vacancy-Rich BiVO4 Photoanode by NiFe-MOFs Thin Layer for Water Oxidation

The introduction of oxygen vacancies (Ov) has been regarded as an effective method to enhance the catalytic performance of photoanodes in oxygen evolution reaction (OER). However, their stability under highly oxidizing environment is questionable but was rarely studied. Herein, NiFe-metal-organic framework (NiFe-MOFs) was conformally coated on oxygen-vacancy-rich BiVO4 (Ov-BiVO4) as the protective layer and cocatalyst, forming a core-shell structure with caffeic acid as bridging agent. The as-synthesized Ov-BiVO4@NiFe-MOFs exhibits enhanced stability and a remarkable photocurrent density of 5.3 +/- 0.15 mA cm(-2) at 1.23 V (vs. RHE). The reduced coordination number of Ni(Fe)-O and elevated valence state of Ni(Fe) in NiFe-MOFs layer greatly bolster OER, and the shifting of oxygen evolution sites from Ov-BiVO4 to NiFe-MOFs promotes Ov stabilization. Ovs can be effectively preserved by the coating of a thin NiFe-MOFs layer, leading to a photoanode of enhanced photocurrent and stability.

Automated summary

The use of NiFe-MOFs coating on oxygen-vacancy-rich BiVO4 to form a core-shell structure has been shown to enhance the photocurrent density and stability of the photoanode.