Continuous electroconversion of CO2 into formate using 2 nm tin oxide nanoparticles

Abstract

Tin oxide nanoparticles (SnO2 NPs) as electrocatalyst for the production of formate from CO2 reduction reaction (CO2RR). We synthesize, characterize and evaluate high surface area SnO2 NPs (2.4 nm and 299 m2 g-1 in diameter size and surface area, respectively), for the continuous production of formate at high current density within a flow electrolyzer. SnO2 NPs under Ar and CO2 reduction conditions were studied by cyclic voltammetry. SnO2-based gas diffusion electrodes (SnO2-GDEs) were manufactured to perform continuous CO2RR. A maximum formate concentration value of 27 g L-1 was achieved with a Faradaic efficiency (FE) of 44.9 % at 300 mA cm-2, which was significantly stable and reproducible when operated up to 10 h. Nevertheless, ohmic drop contribution due to the semiconducting properties of SnO2 was not negligible. The low total FE (< 60 %) of products pointed out a leakage of formate by crossover migration through the membrane from the catholyte towards the anolyte.