Understanding the Improved Activity of Dendritic Sn₁Pb₃ Alloy for the CO₂ Electrochemical Reduction: A Computational-Experimental Investigation

An alloy of Sn and Pb (Sn1Pb3) was prepared by electrodeposition at large negative current. The deposit is porous, with a honeycomb-like primary structure and a dendritic-like secondary structure. The onset potential for the electroreduction of CO2 is 80 mV lower on dendritic Sn1Pb3 as compared to dendritic Pb. The faradaic efficiency for formate formation is close to 100% in the potential range from -1.16 to -1.56 V vs. SHE. Density functional theory (DFT) computations were performed to uncover the origin of the decrease in the onset potential upon alloying Pb with Sn. Explicit treatment of water molecules in DFT calculations turns out as crucial to achieve an agreement with experimentally measured onset potentials.