Title : fcc/2H and fcc/4H copper nanodisks for carbon dioxide reduction
The nanosized fcc/hcp (face centered cubic/hexagonal close-packed) noble metal heterostructures have demonstrated excellent catalytic performance towards hydrogen evolution reaction and CO2 reduction reaction. Among all the monometallic catalysts, copper has drawn great attention because of its unique ability to convert CO2 into hydrocarbon products with an appreciable selectivity. However, the wet-chemistry synthesis of fcc/hcp Cu nanostructure still remains a great challenge. Herein, we reported a high temperature solution reduction method to synthesize fcc/hcp Cu nanodisks with a thickness of 26.5 ± 2.3 nm and diameter of 85.6 ± 3.7 nm. The Cu nanodisks exhibited high selectivity towards CO2 reduction reaction and high faradaic efficiency for methane (60.4%) production at -1.25 V vs reversible hydrogen electrode (RHE). Transmission electron microscopy (TEM) revealed copious atomic interfaces of fcc/2H and fcc/4H heterostructures on the side surface of the nanodisks (2H/4H: hexagonal close-packed crystal structures with stacking sequence of “AB” and “ABCB”, respectively). Density functional theory calculations suggested that the fcc/2H and fcc/4H heterostructures possess lower ΔG*CHO compared to the pure fcc structure, indicating a lower kinetic barrier for CO2 reduction reaction.