Highly Dispersed Few-Nanometer Chlorine-Doped SnO₂ Catalyst Embedded in a Polyaniline Matrix for Stable HCOO^– Production in a Flow Cell

With the spread of alternative energy plants, electrolysis processes are becoming the protagonists of the future industrial generation. The technology readiness level for the electrochemical reduction of carbon dioxide is still low and is largely based on precious metal resources. In the present work, tin ions are anchored on a polyaniline matrix, via a sonochemical synthesis, forming a few atomic layers of chlorine-doped SnO₂ with a total loading of tin atom load of only 7 wt %. This catalyst is able to produce formate (HCOO^-) with great selectivity, exceeding 72% of Faradaic efficiency in the first hour of testing in 1 M KHCO₃ electrolyte, with a current density of more than 50 mA cm^-2 in a 2 M KHCO₃ electrolyte flow cell setup. Catalyst stability tests show a stable production of HCOO^- during 6 h of measurement, accumulating an overall TON_{HCOO^-} of more than 10,000 after 16 h of continuous formate production. This strategy is competitive in drastically reducing the amount of metal required for the overall catalysis.