F-coordinated single-atom Ru species: efficient and durable catalysts for photo-thermal synergistic catalytic CO2 hydrogenation to methane†

Abstract

Elucidating the correlation between coordination structures and catalytic performances of single-atom active sites is imperative for the precise design of highly efficient catalysts; however, the feasible regulation of coordination environments in single-atom catalysts presents a formidable challenge. Herein, we fabricate single-atom Ru-based catalysts with Ru–F₄ and Ru–O₄ configurations (named Ru–F₄ SAs/PA and Ru–O₄ SAs/PA, respectively), demonstrating that fine-tuning of the coordination structure of Ru sites can significantly enhance performances for CO₂ hydrogenation to methane under mild conditions in a photo-thermal synergistic catalytic process. Comparative studies reveal that Ru–F₄ SAs/PA outperformed Ru–O₄ SAs/PA counterparts, giving superior CO₂ methanation performances with a CH₄ production rate of 47.4 mmol g_cat⁻¹ h⁻¹ and CH₄ selectivity of 93.8% at 200 °C in the presence of light irradiation (200–1100 nm, 1.9 W cm⁻²) under atmospheric pressure. Theoretical investigations unravel that the transition from Ru–O₄ to Ru–F₄ coordination environments optimizes the electronic states, thereby enhancing the adsorption of reactants and intermediates. Moreover, the optimized electronic structure promotes the production and transformation of key intermediate species, lowers the energy barrier for CO₂ conversion, and thus elevates the catalytic activity. This comprehensive study not only clarifies the relationship between the coordination structures of active sites and catalytic performance at the atomic-level but also offers a novel paradigm for the design of efficient CO₂ conversion catalysts.