Efficient photothermal CO2 methanation over NiFe alloy nanoparticles with enhanced localized surface plasmon resonance effect

The methanation of CO2 using green hydrogen not only consumes CO2 as a carbon resource but also stores H-2 with high density. However, the activation of CO2 molecules under mild conditions is challenging due to their inert nature. Herein, we report an efficient photothermal catalytic system using light irradiation which realizes the complete conversion of CO2 to methane without external heating. Over optimum bimetallic NiFe nanoparticles (NPs) with a Ni/Fe atomic ratio of 7, the CO2 conversion can reach up to 98% with a CH4 selectivity of 99%, and no catalyst deactivation was observed for more than 100 h, outperforming the reported catalysts. The catalytic performance is strongly dependent on the structure promoters, light absorption efficiency, NiFe particle sizes, and Ni/Fe ratio. The NiFe alloy NPs with an average size of similar to 21 nm dispersed on alumina nanosheets are evidenced to enhance the localized surface plasmon resonance (LSPR) effect, thus efficiently triggering the CO2 methanation. This work emphasizes and clarifies the important role of LSPR in CO2 hydrogenation, which may benefit the rational utilization of CO2 using solar power.