Selective CO₂ Reduction over Rose’s Metal in the Presence of an Imidazolium Ionic Liquid Electrolyte

The electrochemical reduction of CO2 into reduced carbon compounds is a compelling strategy to sustainably synthesize fuels and commodity chemicals using renewable energy sources. Although promising post-transition metal electrocatalysts have been developed from monometallic thin films, limited effort has been dedicated to the use of trimetallic alloys for CO2 electrocatalysis. In this work, we have explored the electrocatalytic effect of alloying Sn, Pb, and Bi, which are all reported as being individually active catalysts for CO2 reduction to different extents. It is demonstrated that the well-known soldering alloy Bi50Sn22Pb28 (Rose’s metal = RM) promotes the conversion of CO2 to CO in MeCN electrolyte containing millimolar concentrations of the ionic liquid additive [BMIM]OTf. Planar RM electrocatalysts evolve CO with Faradaic efficiencies as high as 95% with average geometric current densities of jtot = 3–10 mA/cm2. XPS analysis shows evidence for the accumulation of metal oxides on the RM surface following CO2 electrocatalysis, which may influence the activity of the alloy.