Sn nanoparticles deposited onto a gas diffusion layer via impregnation-electroreduction for enhanced CO2 electroreduction to formate

Sn-based gas diffusion electrodes (GDEs) are promising for electroreduction of CO2 to formate (ERCF) as they can alleviate CO2 mass transfer limitations. However, current electrodes suffer from large catalyst size or poor electron and/or ion connections. This limits ERCF performance. Here, we report a Sn-based GDE (IE-Sn) for ERCF fabricated via deposition of Sn nanoparticles onto a gas diffusion layer by using an impregnation-electroreduction method. The characterization results showed that the IE-Sn has small Sn catalyst size (16 nm) and excellent electronic and ionic transfer properties. Moreover, the faradaic efficiency (87.12 +/- 4.28%) and partial current density for formate (62.79 +/- 5.33 mA cm(-2)) obtained from the IE-Sn is 2.45-fold and 4.86-fold, respectively, of those of the traditional electrode. This ERCF performance is one of the best among recently reported Sn-based GDEs under similar conditions. Further analyses reveal that the enhanced ERCF performance of the IE-Sn is linked to the large electroactive surface area, enhanced adsorption capacity and chemisorption ability of CO2, better stabilization of CO2 center dot- intermediate, and excellent ion/electron transfer. This study offers design rules to fabricate high-performance electrode materials for ERCF. (C) 2020 Elsevier Ltd. All rights reserved.