Enhanced photocathodic protection performance of Co3S4 nanoparticles modified porous BiVO4 composites for 304 stainless steel

A nanoporous Co₃S₄/BiVO₄ composites were successfully fabricated via electrodeposition, immersion and oil-bath heating methods. ZIF-67 was used as a cobalt source and template. Co₃S₄/BiVO₄ obtained by treatment for 6 h displayed the best photocathodic protection (PCP) performance. Under light, Co₃S₄–6 h/BiVO₄ reduced the potential of 304 stainless steel (SS) to −490 mV vs. SCE, which was 200 mV below that of pure BiVO₄. In addition, the photocurrent densities of 304 SS coupled with Co₃S₄–6 h/BiVO₄ were up to 13 μA cm⁻², which was more than 4 times that of pure BiVO₄. Remarkably, the R_ct of 304 SS coupled with Co₃S₄–6h/BiVO₄ (142.6 Ω·cm²) was 1/27 of that of pure BiVO₄ (3918 Ω·cm²). The outstanding PCP property of Co₃S₄/BiVO₄ can be owed to the synergistic effects of strong visible light absorption, improved charge transfer efficiency, and enhanced electron storage capacity. These advantages make Co₃S₄/BiVO₄ a promising candidate for providing effective PCP effects on metals.