Binary alloys composed of a first row transition metal and a Group 13 post-transition metal are an untapped source of electrocatalysts for the reduction of CO2 to CO, methanol, and a variety of carbon-carbon bonded products. For example, we have reported that Ni3Al reduces CO2 to a variety of C3 oxygenates, while Lewis et. al. has noted that various NixGay alloys generate C2 products from CO2. In both cases, the higher order products are observed in low yield. However, these examples are important since they demonstrate that metallic systems that do not contain copper can form carbon-carbon bonds from CO2. Now we report that appropriately selected bimetallic combinations can produce oxalate in high faradaic yield at modest overpotentials. Previous reports of oxalate electrogeneration from CO2 involved very negative potentials (~–2.0 V vs NHE) necessitating the use of nonaqueous electrolytes. We now find that the overpotential can be reduced to the point that this transformation can be carried out in aqueous electrolyte at potentials where oxalate formation competes favorably with H2 production. Unlike prior work that has suggested the coupling of CO2 to produce oxalate involves the initial reduction of CO2 to form a carbon dioxide radical anion, the process presented here appears to proceed through a CO intermediate.

Copper-free metallic catalysts for the reduction of CO2 to a broad spectrum of organic products

256th National Meeting (2018)

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