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

Highlights: • Sn catalysts deposited onto a GDL via an impregnation-electroreduction method. • Small catalysts size with good ion/electron transfer properties was obtained. • The as-prepared electrode exhibited an excellent ERCF performance. -- Abstract: 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^.– intermediate, and excellent ion/electron transfer. This study offers design rules to fabricate high-performance electrode materials for ERCF.