Electrodeposited Tin-Antimony Alloys as Novel Electrocatalysts for Selective and Stable Carbon Dioxide Reduction to Formate

The activity of SnSb alloy films as electrocatalysts for the CO(2)reduction reaction (CO2RR) to formate was presented for the first time. The effects of the film composition, electrochemical potential, and nature and concentration of the supporting electrolyte on the activity and long-term stability of these catalysts were evaluated. Sn(9)Sb(1)alloy exhibited improved long-term stability when compared to pure Sn films, and this was attributed to the lower insertion of alkali and lower formation of hydride species, inhibiting the electrode disintegration. Additionally, the Sn(9)Sb(1)film exhibited the highest faradaic efficiency (F.E.) among all prepared films, including pure Sn, reaching 96.2 % at -1.25 V vs. RHE. This was ascribed to the better balance between the number of Sn atoms (active species) exposed on the surface and the induced morphologic effect brought by the presence of Sb, generating cube-shaped crystallites. These structures have a high number of undercoordinated surface atoms (located on the steps, corners, and kinks) and grain boundaries, resulting in more reactive Sn atoms, which serve as CO(2)activation sites, increasing the overall activity and F.E. for formate production.