CoFe prussian blue decorated BiVO4 as novel photoanode for continuous photocathodic protection of 304 stainless steel

The development of efficient photocathodic protection system requires highly active and robust light-absorbing electrodes for promoting the electron transfer from the light-absorber to the protected metal. Herein, we present an extremely active and stable CoFe prussian blue (CoFe-PB) modified BiVO4 film prepared by sequentially dipping the BiVO4 film in K3[Fe(CN)6] and CoCl2 solution, which can realize the long-term protection of 304 stainless steel under simulated solar illumination. Particularly, the photocathodic protection process can be operated in a scavenger-free environment. Our mechanism studies reveal that the CoFe-PB overlayer acts as the hole storage layer which can effective extract the photo-generated holes from the BiVO4 photoanode, and meanwhile works as an efficient catalyst that overcome the slow water oxidation barrier at the electrode/liquid interface, and thus greatly increase the electron lifetime, thereby enhancing the photocathodic protection capability. Our work provides a rather simple and effective design strategy for constructing semiconductor/electrocatalysts system for the underlying photogenerated cathodic protection application.