Preparation of ZIF-67/BiVO4 composite photoanode and its enhanced photocathodic protection performance of 316 SS under visible light

Abstract

BiVO4 is a potentially promising photoanode for photocathodic protection (PCP) of metals. Nonetheless, the fast charge recombination and low electron mobility restrict its further utilization. In this work, a cobalt-based metal-organic frameworks (MOFs), zeolitic imidazolate framework-67 (ZIF-67) is incorporated to form the composite ZIF-67/BiVO4 via a facile electrodeposition method. Results show that the ZIF-67/BiVO4 photoanodes present significantly enhanced PCP performance for 316 stainless steel (SS) in comparison with pure BiVO4. The ZIF-67 modified BiVO4 composites with electrodeposition time of 150 s possess the optimal protection performance. The open circuit potential of 316 SS coupled with ZIF-67/BiVO4 could reach − 0.52 V vs. SCE under visible light irradiation in 3.5 wt% NaCl solution without the hole scavengers. The incorporation of ZIF-67 could enhance the visible light absorption ability (λ > 500 nm). In addition, the sensitization of ZIF-67, the increased specific surface area, and the construction of Z-scheme heterojunctions could dramatically promote the separation of electron-hole pairs and retain the strong redox ability of holes or electrons. The photocurrent density of ZIF-67/BiVO4 could reach 99 μA cm−2, which is about 2.5 times that of pure BiVO4. This work shows that porous ZIF-decorated BiVO4 photoelectrodes can provide highly effective PCP for metals, which suggests a promising idea for designing other BiVO4-based photoelectrodes.