Ce Lattice-Engineered In ₂ O ₃ with Au Directs C−C Coupling in Photocatalytic Methane Oxidation

Photocatalytic oxidative coupling of methane is a promising route for methane valorization under mild conditions but remains limited by inefficient C−H activation and poor control over C−C coupling. Herein, we report an efficient Au/Ce1−In2O3 photocatalyst, in which substitutional Ce lattice doping and Au nanoparticle decoration cooperatively enable selective CH4 conversion to C2+ hydrocarbons. Ce incorporation tailors the local In−O lattice environment, enhancing CH4 adsorption, C−H dissociation, and stabilization of surface *CH3 intermediates. In contrast, Au nanoparticles serve as preferential sites for *CH3 coupling and controlled oxygen activation, enabling spatial separation of CH4 activation and C−C formation. As a result, Au/Ce1−In2O3 affords a high C2+ production rate of 4.53 × 103 μmol g−1 h−1 with 93% selectivity, together with sustained stability for 45 cycles and a turnover number of 2194. Mechanistic insights from in situ spectroscopies and density functional theory calculations unveil that Ce lattice doping directs the reaction pathway toward efficient C−C coupling. This work establishes lattice engineering as a powerful strategy for selective photocatalytic methane valorization.