Heterogeneous Catalysts with Well‐Defined Active Metal Sites toward CO2 Electrocatalytic Reduction

Abstract The global atmospheric CO 2 concentration reached 147% of pre‐industrial levels in 2019, and is still increasing with an accelerated rate. A series of methods have been developed to convert CO 2 to other non‐greenhouse molecules. Elelctrocatalytic CO 2 reduction reaction (CO2RR) is one of the promising methods, since it could support renewable energy. Optimizing the CO2RR system requires finding highly efficient catalysts, as well as electrolysis systems. In this essay, the development of promising heterogeneous catalysts with well‐defined active metal sites is discussed. These catalysts could be prepared by immobilizing metal cations onto chemically well‐defined substrates, such as metal‐organic frameworks, covalent‐organic frameworks, polyoxometalates, or immobilizing well‐defined molecular catalysts on conducting substrates. A clear perspective on the catalyst's structures contributes to the understanding of structure‐reactivity correlations, which could, in turn, shed light on designing better catalysts. Some methods to assist the electrocatalysis process, such as coupling with solar or heat energy, are also briefly discussed.