Plasmon-Driven Reaction Selectivity Tuning for Photoelectrochemical H₂O₂ Production

Photoelectrochemical (PEC) H₂O₂ production has gained interest as a green, promising route to produce valuable chemicals. However, it suffers from low H₂O₂ Faradaic efficiency due to competing O₂ generation. Here, we propose a plasmon-driven band structure engineering strategy to thermodynamically regulate the product selectivity of a metal oxide based PEC photoanode. It is demonstrated that the plasmonic near-field generated by the periodically patterned Au nanosphere arrays (Au-PAT) effectively modulates the surface photovoltage and energy band structure of the BiVO₄ photoanode. This modulation helps photoinduced charge carriers to satisfy the thermodynamic potential required to shift the water oxidation reaction (WOR) product from O₂ to high-value H₂O₂. As a result, BiVO₄/Au-PAT achieves a H₂O₂ Faradaic efficiency approximately 3.3 times higher than that of pristine BiVO₄. These findings suggest the effectiveness of external modulation, originating from a plasmonic near-field effect, in regulating the WOR pathway, providing an efficient and selective route to value-added PEC production.