Decoupling Photochemical and Thermal Pathways in Photothermal CO2-to-Methanol Hydrogenation over In2O3-CeO2 Heterojunctions

The hydrogenation of carbon dioxide (CO2) to methanol (CH3OH) using green hydrogen is a key pathway in sustainable energy conversion. However, conventional thermocatalytic routes are fundamentally constrained by thermodynamic and kinetic barriers, especially under ambient conditions. Here, we report a one-pot synthesized, non-noble In2O3–CeO2 heterojunction catalyst that achieves benchmark CO2-to-CH3OH conversion rates under visible-light irradiation at ambient pressure. At 247.7 °C, the optimized catalyst (In3+:Ce3+ = 1:1) delivers a CH3OH production rate of 1054.6 μmol g-1 h-1 with 53.1% selectivity - exceeding, to the best of our knowledge, all previously reported non-noble photothermal systems operating under comparable conditions. Supported by both theory (DFT) and operando spectroscopy (e.g., DRIFTS), the mechanistic origins of the observed activity are attributed to a synergistic interplay among oxygen vacancies, surface hydroxyls, and Ce3+/Ce4+ redox cycles, which collectively enhance CO2 activation and promote selectivity. In addition, we identify a distinct pathway wherein photogenerated charge carriers directly contribute to the catalytic cycle, beyond purely thermal effects. This work outlines a mechanistically guided strategy for designing efficient, scalable, and non-noble photothermal catalysts for solar-assisted CO2 valorization.