A Synchronous <i>d</i>–<i>p</i> Hybridization and Protonated State Regulation Strategy for Efficient H₂O₂ Photosynthesis through Optimized Water Oxidation

Photocatalytic H₂O₂ synthesis with Fe-based cocatalysts is sustainable but limited by sluggish water oxidation reaction (WOR) kinetics and low selectivity from weak *OH intermediate adsorption and instability. To address this, a "Fe-O-P d-p hybridization synergistic protonated state regulation" strategy is devised to enhance the WOR rate and H₂O₂ selectivity. A dual-cocatalyst FeOOH/BiVO₄/Au, synthesized via two-step photodeposition, optimizes active sites and suppress charge recombination, with Au as oxygen reduction reaction active sites while FeOOH as WOR active sites. Subsequent phosphoric acid impregnation generates H₂PO₄ ^-@FeOOH/BiVO₄/Au, wherein Fe-O-P d-p hybridization modulates *OH adsorption and protonation state regulation enhances selectivity toward the two-electron WOR pathway. The optimized H₂PO₄ ^-@FeOOH(1%)/BiVO₄/Au(3%) catalyst achieved a high H₂O₂ yield of 2321 μmol L^-1 in 3 h, 6 times higher than FeOOH/BiVO₄/Au, and the best among reported Bi-based photocatalysts under pure water. Density functional theory and in situ Fourier transform infrared spectroscopy showed that Fe-O-P hybridization raises the Fe d-band center and strengthens *OH adsorption, accelerating electron transfer during WOR. This work offers a new design concept for efficient WOR cocatalysts to boost photocatalytic H₂O₂ production.