Rational Design of Heterogeneous Dual-Atom Catalysts for CO2 Electroreduction Reactions

One of the strategies to mitigate the concentration of CO2 in the atmosphere and reduce the global warming effect is to capture CO2 and convert it to synthetic fuels and fine chemicals. Although CO2 is structurally and chemically stable, the electrochemical transformation has attracted much attention because it offers mild reaction conditions regarding temperature, pressure, and process controllability. Among various electrocatalysts, dual-atom catalysts (DACs) have been extensively developed in the past few years due to their unique features for the electrochemical reactions of small molecules. The catalytic activity of DACs in the electrochemical CO2 reduction reaction (eCO2RR) has surpassed single-atom catalysts (SACs) by providing a higher metal loading, two active sites (cf. one active site for SACs), a synergistic effect of adjacent metal atoms, the possibility of tuning the electronic state (adjusting the d-band center), and more possible configuration modes (side-on and side-bridge) for adsorption of CO2 (cf. only end-on and end-bridge modes for SACs). As a result, both higher reactivity and selectivity in eCO2RR can be achieved by breaking scaling relationships with more possible interactions between intermediates and active sites. This review highlights and discusses the recent progress in applying homo- and heteronuclear DACs for eCO2RR focusing on the synthesis, characterization, and electrochemical catalytic performance.