Selective Photoelectrochemical Water Oxidation to Hydrogen Peroxide via Tip-Induced Interfacial Regulation

Abstract Bicarbonate (HCO3–) electrolytes have significantly promoted photoelectrochemical water oxidation to H2O2 production over the competitive O2 evolution. However, the selectivity and efficiency are still fundamentally constrained by the limited solubility of the HCO3–, the severe charge recombination, and the parasitic decomposition of as-formed H2O2. Here, we construct a BiVO4 nanocone photoanode to simultaneously address these critical challenges via tip-induced interfacial regulations. The spatial charge separation directs photogenerated holes toward the cone vertices, effectively suppressing charge recombination and enhancing photoactivity. The high-curvature tips generate localized electric fields that enrich interfacial HCO3– beyond its solubility limit and decrease the energy barrier of HCO3–-mediated H2O-to-H2O2 conversion. In addition, the tip-induced hydrophobic surface and enhanced mass transport promote rapid H2O2 desorption, mitigating its self-decomposition. As a result, these effects boost the H2O2 faradaic efficiency to 72.0% at 1.6 V vs RHE under AM 1.5G illumination, yielding an 8.6-fold increase in production rate compared to its planar counterparts.