Energy-storing WO3@BiVO4 composite as photocathodic protective coatings

In this work, a micron-scale spherical energy-storing WO3@BiVO4 composite was synthesized through a simple hydrothermal method to achieve photocathodic protection (PCP) in the dark. Then, the WO3@BiVO4 composite was added to the epoxy resin to prepare a PCP coating (EWBV coating). The photoelectrochemical performance of the coating showed that the 304 stainless steel (304ss) coated with EWBV coating obtained a photocurrent density of 250 μA/cm2 and its open circuit potential was negatively shifted by about 300 mV compared to the bare 304ss under illumination. When the light source was turned off, as the WO3@BiVO4 composite has an energy-storage function, the open circuit potential of 304ss coated with EWBV coating was still lower than the bare 304ss (negative shift was about 130 mV). The PCP effect of EWBV coating was maintained for approximately 2 h in the dark. The results show that the EWBV coating has good PCP performance with and without light.