Enhanced Electrochemical Reduction of CO2to CO on Ag/SnO2by a Synergistic Effect of Morphology and Structural Defects

Abstract Silver (Ag)‐based materials are considered to be promising materials for electrochemical reduction of CO 2 to produce CO, but the selectivity and efficiency of traditional polycrystalline Ag materials are insufficient; there still exists a great challenge to explore novel modified Ag based materials. Herein, a nanocomposite of Ag and SnO 2 (Ag/SnO 2 ) for efficient reduction of CO 2 to CO is reported. HRTEM and XRD patterns clearly demonstrated the lattice destruction of Ag and the amorphous SnO 2 in the Ag/SnO 2 nanocomposite. Electrochemical tests indicated the nanocomposite containing 15% SnO 2 possesses highest catalytic selectivity featured by a CO faradaic efficiency (FE) of 99.2% at −0.9 V versus reversible hydrogen electrode (vs RHE) and FE>90% for the CO product at a wide potential range from −0.8 V to −1.4 V vs RHE. Experimental characterization and analysis showed that the high catalytic performance is attributed to not only the branched morphology of Ag/SnO 2 nanocomposites (NCs), which endows the maximum exposure of active sites, but also the special adsorption capacity of abundant defect sites in the crystal for *COOH (the key intermediate of CO formation), which improves the intrinsic activity of the catalyst. But equally important, the existed SnO 2 also plays an important role in inhibiting hydrogen evolution reaction (HER) and anchoring defect sites. This work demonstrates the use of crystal defect engineering and synergy in composite to improve the efficiency of electrocatalytic CO 2 reduction reaction (CO 2 RR).