Electrochemical reduction of CO2 over Sn-Nafion® coated electrode for a fuel-cell-like device

Commercially available Sn particles mixed with Nafion® ionomer are used to prepare an electrode with a gas diffusion layer support in a manner similar to that in which fuel cell electrodes are prepared. Cyclic voltammetry is performed in aqueous NaHCO3 (basic medium) on the electrode and the Tafel parameters are obtained and compared with a Sn metal disc and with a graphite disc coated with Sn powder. In addition, electrolysis is carried out potentiostatically, also in NaHCO3 solution, at various potentials. The exchange current density on the Sn/gas diffusion layer electrode shows to be two orders of magnitude higher that on the metallic Sn disc. The maximum current density obtained during electrolysis is 27 mA cm−2 at −1.6 V vs. NHE, with 70% faradaic efficiency towards the formation of formate, which is one of the highest values found in the literature on Sn electrode at ambient pressure.

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► Commercially available Sn particles for electrochemical reduction of CO2 to formate.
► Measurements of electrocatalytic activity of metallic Sn and Sn powder catalysts.
► CO2 reduction potentiostatically in sodium bicarbonate solution at ambient CO2 pressure.
► The exchange current density of Sn gas diffusion electrode is two orders of magnitude higher over metallic Sn disc.
► Current density of 27 mA cm−2 (−1.6 V per NHE) at 70% faradaic efficiency towards HCOO− formation.