Challenges and opportunities of atomic-scales reactive sites in thriving electrochemical CO₂ reduction reaction

Electrochemical carbon dioxide reduction reaction (ECO2RR) converts CO2 into value-added chemicals or fuels to realize carbon recycling as means to solve the problems of renewable energy shortage and environmental pollution. The development of cost-effective CO2RR catalysts with high activity, stability and selectivity is the key that enables efficient conversion from CO2 to valuable products. It is also important to understand intrinsic mechanisms of the underlying active-site that affect the performances of catalysts, which can, in turn, facilitate the rational design of more active electrocatalysts. In this context, it is particularly important to understand the structure-activity relationship of catalyst active sites during the CO2RR process from different atomic-scales, which inspires to organize this review. Specifically, we focus on the atomic-level construction of active sites from single atoms, dual-site metal, clusters, or/and graphitic carbon materials: key approaches for tailoring coordination configurations to enhance target product selectivity, i.e., optimizing the interplay between the catalytic active center and reactants or intermediates, disrupting the linear correlation of intermediate adsorption energies, and promoting intricate cascading reactions involving multiple intermediates. Highlight the intricate correlation between the structure-activity of CO2RR catalysts, which govern the discerning refinement of catalysts and propel advances in their practical application. Then, the electrocatalytic reactors for ECO2R reactions are critically reviewed. The acquisition of key metrics, the challenges faced, and the most suitable solutions for electrocatalytic CO2RR are proposed. Finally, future research directions and strategies are anticipated to inspire revolutionary advancements.