Multi-effect enhanced photocathodic protection performance of 304 SS for atom-shared Bi/BiVO4/Bi2S3 photoanode based on decahedral BiVO4

Abstract

The easily charge recombination and low electron transfer efficiency have limited the enhancement of photocathodic protection (PCP) performance of BiVO₄. In this study, Bi atom-shared Bi/BiVO₄/Bi₂S₃ heterojunction with decahedral BiVO₄ has been prepared by hydrothermal method and then mixed with PVDF to synthesize a photocathodic protection coating on 304 stainless steels (304 SS). Both the effect of morphology and the atom-shared Bi/BiVO₄/Bi₂S₃ heterojunction on microstructure and PCP performance of BiVO₄ were analyzed. Results indicate decahedral BiVO₄ has obtained higher PCP performance than normal BiVO₄, because the electrons and holes respectively accumulate at the (010) and (110) faces in decahedral BiVO₄ to promote e⁻/h⁺ pairs' separation. Then PCP performance of 304 SS has further enhanced for Bi atom-shared Bi/BiVO₄/Bi₂S₃ photoanode, with the significantly increased photocurrent density of 160 μA cm² and the more negative open circuit potential of −0.85 V vs Ag/AgCl. After comparing between Bi-shared Bi/BiVO₄/Bi₂S₃ and Bi/BiVO₄@Bi₂S₃ without sharing atom, we found that the best PCP performance for Bi/BiVO₄/Bi₂S₃ were resulted from three effects: the atomic-level contacts between BiVO₄ and Bi₂S₃ in Bi atom-shared heterojunction to enhance electron transfer efficiency, decahedral BiVO₄ to separate carriers and localized surface plasmon resonance (LSPR) effect of Bi to generate more thermalelectrons to transfer to 304 SS. This research offers a strategy to improve PCP capability of BiVO₄ through multi-effect of tuning the morphology and building atom-shared heterojunction.