Tandem Electroreduction of CO₂ to C2+ Products Based on M-SACs/Cu Catalysts

Electrochemical CO₂ reduction reaction (ECO₂RR) is considered a highly promising method to produce high-value chemicals and fuels, contributing significantly the artificial carbon balance. Plenty catalysts can facilitate the conversion of CO₂ into mono-carbon (C1) products. Among these catalysts, Cu species exhibit a distinct role in the formation of multi-carbon (C2+) products characterized by enhanced energy density. However, the limited selectivity of C2+ products, along with the inferior stability, and high overpotential demonstrated by single-component Cu catalysts, hinders their applicability in industrial-scale production. The implementation of a tandem strategy, which involves coupling the CO₂-to-CO pathway using Ag, Au, metal single-atom catalysts (M-SACs), etc., with the CO-to-C2+ conversion on Cu, represents a novel approach for the efficient generation of C2+ products. Given the high cost and restricted availability of noble metals, M-SACs have attracted substantial interest in tandem systems due to their cost-effectiveness and efficient atom utilization. The systematic analysis of the design principles and structure-activity relationship is essential for the advancement of M-SACs/Cu-based tandem catalysts. Here we first introduce various prevalent design strategies of M-SACs/Cu-based tandem catalysts for ECO₂RR and then systematically summarize the latest advancements of M-SACs/Cu-based tandem system, encompassing metal-organic frameworks/Cu (MOFs/Cu), covalent organic frameworks/Cu (COFs/Cu), and nitrogen-doped carbon support transition metal single atomic materials/Cu (M-N-C/Cu). Lastly, we discuss the challenges and opportunities with the design and construction of M-SACs/Cu-based tandem catalysis for ECO₂RR.