Strategies for the proton-coupled multi-electron reduction of CO2 on single-atom catalysts

Catalytic reduction of CO2 to high value-added chemicals is an important approach for tackling the rising CO2 concentration in the atmosphere. Recently, a range of heterogeneous and potentially low-cost single-atom catalysts (SACs) have emerged as promising candidates for the reduction of CO2. However, in comparison to conventional metal nanoparticle catalysts, SACs have long faced challenges in reactions involving multiple reactants and multiple reaction steps due to the limitation of isolated metal sites. This review presents the most recent research advances on the development of single-atom catalysis for deep reduction of CO2. Based on the approaches proposed for proton-coupled multi-electron transfer, detailed introductions and summaries were classified into three categories: 1) strengthen the metal-support interaction to achieve a synergistic catalysis; 2) rational design and regulation of the coordination environment of isolated metal atoms; 3) development of SACs with multi-atom active sites. Finally, the main challenges and future research directions in the field of SACs for CO2 reduction are proposed.