Photothermal CO₂ methanation over (NiO/Ru⁰)/TiO₂ catalysts via hydrogen spillover.

Abstract

Photothermal CO₂ methanation presents a promising strategy for mitigating the energy crisis and reducing CO₂ emissions, however, the critical role of hydrogen migration dynamics in addressing reaction kinetics and thermodynamics has not been thoroughly investigated. Here, we demonstrate the design of a (NiO/Ru⁰)/TiO₂ photothermal catalyst with optimized interfacial architecture and enhanced hydrogen mobility, which facilitates exceptionally selective conversion of CO₂-to-CH₄. Both experimental and theoretical analyses reveal that H₂ dissociates efficiently on Ru⁰, subsequently undergoing spillover to O in NiO (O_NiO). This process not only redistributes active sites but also influences the reaction kinetics, thereby fundamentally altering the energy landscape associated with CO₂ methanation. Consequently, the (NiO/Ru⁰)/TiO₂ catalyst achieves complete CO₂ conversion and CH₄ selectivity, with a CH₄ production rate of 2552.49 μmol h^-1 (85.08 mmol g^-1 h^-1) under an irradiation of 25.5 suns without external heat or pressure. This research underscores an innovative engineering approach that leverages hydrogen spillover to enhance photothermal catalytic efficiency and selectivity, thereby providing a robust framework for the advancement of sophisticated photothermal catalysts for selective CO₂ hydrogenation.