Synergistic physical confinement and chemical adsorption in yolk-Shell Ni@NC nanoreactors for enhanced photothermal CO2 methanation

Solar-driven photothermal conversion of dilute CO 2 into CH 4 offers a promising route toward carbon-neutral energy cycles, yet designing efficient catalysts for realistic low-concentration streams remains challenging. Herein, a yolk-shell structured nanoreactor composed of homogeneous Ni@NC units (denoted as Ni@NC-9 h) was fabricated via a time-controlled solvothermal and pyrolysis method. This unique architecture acts as a confined nanoreactor that integrates physical and chemical enrichment mechanisms: the internal cavity simultaneously enhances light harvesting and thermal localization via multiple scattering and increases local CO 2 coverage, while the homogeneously distributed nitrogen sites ensure efficient chemical trapping of dilute CO 2 . Under mild conditions (420 nm LED, 180 °C, 12.5% CO 2 , 86.9 mW·cm −2 ), the Ni@NC-9 h catalyst achieves a remarkable CH 4 production rate of 4.33 mmol·g −1 ·h −1 with 94.7% selectivity. Kinetic and in-situ DRIFTS insights uncover a photothermally reduced activation barrier that drives efficient stepwise hydrogenation through *COOH and *CO intermediates. This work provides insights into confinement-enhanced nanoreactor design and establishes a new structural paradigm for the efficient solar-driven upgrading of dilute CO 2 .