Persistent photothermal CO2 methanation without external energy input

Abstract

Photothermal CO2 methanation is crucial for carbon neutralization and long-term space exploration, but the reliance on sunlight irradiation limits its practical application. Herein, a fluorite two-dimensional solid solution of NiO and CeO2 (2D Ni1Ce1O3) is synthesized for low-temperature CO2 methanation, resulting in 80±4 and 2125±43 mmol g-1 h-1 of CH4 production rates at 200 and 300 °C respectively, with 99.58±0.12% CH4 selectivity. It is attributed to that 2D Ni1Ce1O3 strengthens the CO2 adsorption and changes the CO2 methanation paths. When we used a homemade TiC/Cu based device to absorb sunlight to heat the catalyst, the 2D Ni1Ce1O3 shows a photothermal CO2 methanation rate of 2901 mmol g-1 h-1 under weak sunlight irradiation and more interestingly a robust CO2 methanation rate of ~830 mmol h-1 under dark environments. Consequently, the outdoor demonstration could drive CO2 methanation for five continuous outdoor days and nights with a total CH4 yield of 898 m3 and 10 tons of boiled water, showing the industrial potential of photothermal CO2 methanation.