Recent advances in CO2 hydrogenation to methane using single-atom catalysts

Single-atom catalysts (SACs) with isolated metal atoms dispersed on a solid support have been a hot topic in the last decade in heterogeneous catalysis. In a comprehensive attempt to minimize CO2 emissions with a persisting effect on global warming, the catalytic conversion of CO2 to methane can facilitate the convenient storage of excess energy as a green natural gas. Herein, we narrow the scope of this review by focusing on recent reports on thermocatalytic CO2 methanation using SACs with a special focus on the design and optimization strategies and existing challenges to overcome to get high selectivity and activity. It is highlighted that for higher selectivity towards methane over the CO product in CO2 hydrogenation, H2 dissociation and strong CO binding as an intermediate over the catalyst surface are the key steps. These insights are vital for determining the design principles of upcoming SACs to make them more efficient and selective in CO2 methanation.