Solar‐Driven Photothermal Manufacturing of Defect‐Rich Oxide Interfaces for Biomass Electrocatalysis

ABSTRACT Defect‐rich metal oxides are central to sustainable electrocatalysis, yet conventional heat treatment is generally constrained by thermodynamic equilibrium, limiting precise control over defect chemistry while requiring substantial energy input. Here, we establish a solar‐driven photothermal synergistic sintering (PTS) strategy for non‐equilibrium defect engineering by coupling ultraviolet‐induced metal‐oxygen bond activation with localized photothermal lattice reconstruction. Applicable to representative transition‐metal oxide systems, including Co 3 O 4 , CuO, NiO, MnO, and NiCoMnO, PTS rapidly generates oxygen‐vacancy‐enriched hetero‐ and homophase oxide architectures. Using cobalt oxides as a model system, we show that the resulting Co 3 O 4 /CoO heterophase interfaces act as dynamic precatalytic platforms that promote low‐potential surface Co oxidation and subsequent high‐valent CoOOH formation while facilitating HMF‐derived intermediate activation. Density functional theory calculations reveal that the heterophase interface optimizes OH − adsorption, lowers the free‐energy barrier for surface Co oxidation, and enhances HMFCA adsorption and activation. Consequently, the PTS‐derived catalyst delivers a 2.5‐fold higher apparent geometric current density (474 mA cm −2 at 1.40 V vs. RHE) for 5‐hydroxymethylfurfural electrooxidation while maintaining Faradaic efficiency and FDCA yield above 95% over 50 cycles. This work establishes solar‐driven PTS as a general non‐equilibrium strategy for programming oxide defect chemistry and interfacial structures toward sustainable biomass electrocatalysis.