Ru-Induced Electron-Rich Ni⁰ sites driving CO*-Mediated pathway toward highly selective photothermal CO₂ methanation

The catalytic hydrogenation of CO₂ to methane using renewable hydrogen is essential for closing the carbon cycle and storing green energy. A pivotal challenge is to overcome the high activation barrier of inert CO₂ and the ambiguous reaction network in photothermal catalysis, which necessitates precise electronic structure engineering of catalysts to optimize the activation of both CO₂ and H₂ under mild conditions. Here, we develop a Ru-promoted LaNiO₃ perovskite catalyst, in which Ru doping induces lattice contraction, increases oxygen vacancies, and enriches the electron density of surface Ni⁰ sites. This electronic optimization enhances broadband light absorption, charge separation, catalyst reducibility and photothermal conversion. Under photothermal conditions, the catalyst exhibits a 365% higher CH₄ formation rate at 270 °C than that under thermal catalysis alone, with > 94% CH₄ selectivity and excellent stability. In situ DRIFTS shows that Ru significantly enhances the CO*(adsorbed CO intermediate)-mediated pathway alongside the formate route. Photogenerated electrons further accelerate the conversion of intermediates, enabling cooperative deep hydrogenation of CO₂ to CH₄. This work reveals the multifaceted role of Ru in regulating catalyst reducibility, electronic structure, and reaction pathways, providing a rational design strategy for highly selective photothermal CO₂ hydrogenation catalysts.