Indium Arsenide Quantum Dot Derived Catalyst for Selective CO₂ Electrochemical Reduction to Formate

Despite a currently limited market size, formate is finding innovative applications as a hydrogen carrier and carbon source for upgrading processes to hydrocarbons and oxygenates. In this study, we combine the unique key features of In-based electrodes in the electrocatalytic CO2 reduction reaction (e.g., limited hydrogen evolution reaction activity, near-to-unity carbon selectivity toward formate) with the remarkable results obtained using nanostructured and highly defective quantum dot derived catalysts. After developing a scalable, safe and cheap InAs quantum dots synthesis based on a mild and nonpyrophoric reducing agent (i.e., NaCNBH3), a thorough voltammetric study allowed us to retrieve kinetic and thermodynamic data on their transformation into the actual catalytically active species (i.e., In-0). In a flow electrolyzer operating under alkaline conditions at industrially relevant current densities, the catalyst achieved near-to-unity faradaic efficiency toward formate, with a remarkable production rate of ca. 1276 g(Formate) h(-1) m(-2) at ca. -0.73 V vs RHE (eta(Formate) = 0.61 V).