oa Comparative Analysis of Single Atom Catalysts and Single-atom Alloy Catalysts for CO2 Methanation

Single-atom catalysts (SACs) and single-atom alloy (SAA) catalysts are emerging as promising catalysts that allow maximising atom efficiency whilst improving catalyst performance. This literature review focusses on the evaluation of SACs and SAAs for thermocatalytic CO2 methanation, providing mechanistic insights into CO2 methanation on SACs and SAAs. The key findings from this review demonstrate that metal clusters (e.g., Ni and Ru) in many cases provide a greater catalytic efficiency on a metal loading basis for CO2 methanation compared to SACs. In contrast, SAAs have demonstrated a notable positive effect on catalyst activity and/or selectivity for CO2 methanation, with studies having identified the benefit of a single-atom alloy structure in providing these enhancements. Therefore, the use of either supported metal clusters (rather than single atoms) or SAAs shows the most potential in maximising metal atom efficiency in thermocatalytic CO2 methanation.