Diatomic Pd catalyst with conjugated backbone for synergistic electrochemical CO2 reduction

Double-site catalysts have attracted widespread attention in the field of electrocatalysis due to their high metal loading, adjustable active centres, and electronic valence states. However, the development of bimetallic sites catalysts that coordinate with definite atoms is still in the exploratory stage. Here, we designed and synthesized a bimetallic palladium complex (BPB-Pd2) with conjugated backbone. The supported BPB-Pd2 was applied to electrochemical CO2 reduction reaction (CO2RR) for the first time. The as-obtained BPB-Pd2 gives an exceptional Faradaic efficiency of CO (FECO) of 94.4% at −0.80 V vs. reversible hydrogen electrode (RHE), which is significantly superior to monoatomic palladium catalyst (BPB-Pd1). The density functional theory (DFT) calculations revealed that the essential reason for the outstanding activity of BPB-Pd2 toward CO2RR was that the electronic effect between diatomic palladium reduces the free energy change for CO2RR process. Thus, BPB-Pd2 exhibits moderate free energy change to form COOH* intermediate, which was beneficial for the generation of CO in CO2RR.