Reinforcing the Efficiency of Photothermal Catalytic CO Methanation through Integration of Ru Nanoparticles with Photothermal MnCoO Nanosheets.

Carbon dioxide (CO) hydrogenation to methane (CH) is regarded as a promising approach for CO utilization, whereas achieving desirable conversion efficiency under mild conditions remains a significant challenge. Herein, we have identified ultrasmall Ru nanoparticles (∼2.5 nm) anchored on MnCoO nanosheets as prospective photothermal catalysts for CO methanation at ambient pressure with light irradiation. Our findings revealed that MnCoO nanosheets exhibit dual functionality as photothermal substrates for localized temperature enhancement and photocatalysts for electron donation. As such, the optimized Ru/MnCoO-2 gave a high CH production rate of 66.3 mmol g h (corresponding to 5.1 mol g h) with 96% CH selectivity at 230 °C under ambient pressure and light irradiation (420-780 nm, 1.25 W cm), outperforming most reported plasmonic metal-based catalysts. The mechanisms behind the intriguing photothermal catalytic performance improvement were substantiated through a comprehensive investigation involving experimental characterizations, numerical simulations and density functional theory (DFT) calculations, which unveiled the synergistic effects of enhanced charge separation efficiency, improved reaction kinetics, facilitated reactant adsorption/activation and accelerated intermediate conversion under light irradiation over Ru/MnCoO. A comparison study showed that, with identical external input energy during the reaction, Ru/MnCoO-2 had a much higher catalytic efficiency compared to Ru/TiO and Ru/AlO. This study underscores the pivotal role played by photothermal supports and is believed to engender a heightened interest in plasmonic metal nanoparticles anchored on photothermal substrates for CO methanation under mild conditions.