Indium Arsenide\nQuantum Dot Derived Catalyst for Selective\nCO₂ Electrochemical Reduction to Formate

Abstract

Despite a currently limited market size, formate is finding\ninnovative\napplications as a hydrogen carrier and carbon source for upgrading\nprocesses to hydrocarbons and oxygenates. In this study, we combine\nthe unique key features of In-based electrodes in the electrocatalytic\nCO₂ reduction reaction (e.g., limited hydrogen evolution\nreaction activity, near-to-unity carbon selectivity toward formate)\nwith the remarkable results obtained using nanostructured and highly\ndefective quantum dot derived catalysts. After developing a scalable,\nsafe and cheap InAs quantum dots synthesis based on a mild and nonpyrophoric\nreducing agent (i.e., NaCNBH₃), a thorough voltammetric\nstudy allowed us to retrieve kinetic and thermodynamic data on their\ntransformation into the actual catalytically active species (i.e.,\nIn⁰). In a flow electrolyzer operating under alkaline conditions\nat industrially relevant current densities, the catalyst achieved\nnear-to-unity faradaic efficiency toward formate, with a remarkable\nproduction rate of <i>ca</i>. 1276 g_Formate h^–1 m^–2 at <i>ca</i>. −0.73\nV vs RHE (η_Formate = 0.61 V).