Unraveling Photothermal Effects in CO₂ Methanation over Ru/C Catalysts under Visible Light

The conversion of CO₂ into value-added fuels is a key strategy for sustainable energy and carbon management. Photothermal catalysis, which harnesses light to generate localized heating, offers a promising approach to enhancing the catalytic performance. Here, we demonstrate a significant enhancement in CO₂ methanation activity over Ru/C catalysts under visible light irradiation driven by photothermal effects. Using an embedded thermocouple at the catalyst bed, we correlated power density, localized catalyst heating, and reaction kinetics, revealing a 145% increase in the reaction rate at 320 °C. Mechanistic studies, including activation energy analysis and power density and wavelength dependence, confirm that the observed enhancements arise predominantly from photothermal activation. Density functional theory calculations reveal that the Ru-C interface serves as the primary active site, enhancing CO₂ adsorption and lowering energy barriers for key intermediates. This interface optimally integrates catalytic and photothermal effects from the carbon support, facilitating light absorption and heating. These findings not only establish Ru/C as an efficient photothermal catalyst for CO₂ methanation but also provide a robust framework for quantifying and optimizing light-driven thermal effects in nanocatalysis. By integrating experimental validation with atomic-scale insights, this study paves the way for the rational design of next-generation photothermal catalysts for sustainable solar-to-fuel conversion.