Oxygen vacancy-mediated photothermal CO2 methanation over Ni/Ce-Zr solid solution catalysts.

Photothermal Carbon dioxide (CO2) hydrogenation is a promising strategy for solar-fuel production, but its performance is often limited by inefficient charge separation and poor low-temperature activity. Herein, Ni/Ce-Zr solid solution catalysts were developed by introducing lattice distortion to regulate the electronic structure and generate abundant oxygen vacancies. The resulting oxygen vacancies promote charge separation, enhance CO2 activation, and strengthen the photothermal synergistic effect. Among the catalysts, 20Ni/Ce0.75Zr0.25O2 exhibited the best performance, achieving 79.02% CO2 conversion, over 99.00% CH4 selectivity, a methanation rate of 26.35 ± 0.05 mmol·gcat-1·h-1, and an apparent activation energy of 16.23 ± 0.70 kJ/mol at 250 °C, while maintaining stable operation for over 180 h. In situ DRIFTS results reveal that abundant oxygen vacancies facilitate the hydrogenation of key intermediates and suppress carbonate accumulation, thereby preventing catalyst deactivation. These findings demonstrate that oxygen-vacancy engineering is an effective approach for improving photothermal CO2 methanation and provide guidance for the design of efficient solar-driven CO2 conversion catalysts.