Functionalizing p-Si/Ag with 2,6-Diaminopyridine for Efficient CO2 Reduction with Enhanced Selectivity at a Low Overpotential

The photoassisted electrochemical CO 2 reduction reaction (CO 2 RR) toward CO is considered one of the most promising routes of CO 2 utilization. In this work, 2,6-diaminopyridine (2,6-DAP) with both the pyridine ring and the –NH 2 functional group is utilized for the first time to functionalize the surface of the electrode. The p-Si/Ag/2,6-DAP electrode has been identified as a good catalyst with relatively high activity and CO selectivity at a low overpotential as well as good stability. The Faradaic efficiency of CO is 84.56% at an optimized potential of −0.9 V vs reversible hydrogen electrode (RHE). A synergistic mechanism has been proposed for the enhanced catalytic performance of p-Si/Ag/2,6-DAP in the CO 2 RR. Ag facilitates the reduction of CO 2 to produce CO. 2,6-DAP helps CO 2 adsorption and inhibits the competitive hydrogen evolution reaction accompanying the CO 2 RR under low potentials.