Inverse MgO–on–Co Interfaces Enable Highly Efficient and Stable Photothermal CO2 Methanation via Regulation of Key Intermediate Conversion

Abstract Photothermal CO2 methanation offers a promising route for converting renewable energy into synthetic methane under mild conditions, but conventional non-noble-metal catalysts typically suffer from limited activity, severe coking, and reliance on auxiliary heating. Herein, we report an inverse-structured MgO/Co catalyst featuring highly dispersed MgO nano-islands on metallic Co nanoparticles, which effectively overcomes these limitations. Under illumination at 2.33 W·cm–2 without external heating, the optimized 5MgO/Co catalyst achieves a remarkable CH4 production rate of 458 mmol·gcat–1·h–1 with a CH4 selectivity of 98.5%, outperforming most non-noble-metal and several noble-metal benchmarks. Furthermore, the inverse catalyst demonstrates outstanding durability, maintaining stable performance over 50 hours with robust coking resistance. In situ spectroscopic studies and theoretical calculations reveal that the inverse MgO/Co interface regulates the adsorption configuration of formate intermediates, thereby accelerating their subsequent hydrogenation toward CH4. Meanwhile, plasmonic Co nanoparticles promote efficient photothermal conversion and interfacial charge transfer, facilitating CO2 activation and H2 dissociation at the oxide–metal boundary. This synergistic coupling of inverse-interface catalysis, localized photothermal heating, and photoinduced electron transfer enables highly efficient solar-driven CO2 methanation, establishing inverse MgO/Co as a powerful platform for robust and selective CO2 upgrading.