Unraveling How Terminal and Bridging Oxygen Species at Reconstructed Metal Oxide Interfaces Enable Efficient Paired FDCA–H 2 Electrosynthesis

ABSTRACT A key challenge in electrocatalytic biomass conversion is the unresolved synergy between terminal hydroxyl (µ 1 ‐OH) and bridged lattice oxygen (µ 2 ‐O) species in metal oxide materials. This work unravels the distinct functions of these two electrophilic oxygen species for paired 2,5‐furandicarboxylic acid (FDCA)–H 2 electrosynthesis by systematically investigating their catalytic behavior in 5‐hydroxymethylfurfural oxidation (HMFOR) at electrochemically reconstructed MO x /NF interfaces. Decoupling the electrochemical–chemical steps of HMFOR reveals that this reaction is governed primarily by µ 1 ‐OH–M n+δ with rapid µ 2 ‐O regeneration, whereas hydrogen evolution reaction (HER) proceeds via µ 2 ‐O‐promoted water dissociation. The outstanding performance of each catalyst aligns with its surface speciation. Ni(OH) x O y /NF, featuring a µ 1 ‐OH‐rich surface, delivers a 97% FDCA yield with 99% Faradaic efficiency for HMFOR. Conversely, CuO x /NF, enriched with µ 2 ‐O, exhibits superior HER activity ( η 10 = 0.16 V, Tafel slope 46 mV dec −1 ). Leveraging these complementary structure–property relationships, an integrated NiO/NF||CuO x /NF electrolyzer achieves highly efficient FDCA–H 2 co‐production. This study establishes a material design framework for managing paired electrosynthesis through electrophilic oxygen synergy at reconstructed metal oxide interfaces.