The Electroreduction of Carbon Dioxide and Formic Acid on Tin and Indium Electrodes

The electrochemical reduction of carbon dioxide and formic acid has been studied in aqueous solutions on tin and indium electrodes using a‐c impedance and photoemission techniques. Carbon dioxide reduction to formic acid (or the formate ion) proceeds with high current efficiencies (about 95%) although the overall power efficiency is low due to the high overpotential of the reaction. The reaction mechanism on tin and indium is similar to that postulated on mercury cathodes (17). The reaction rates are higher than on mercury and are affected by adsorption of intermediates and kinetics complications due to side reactions. Reduction of formic acid was only observed on tin cathodes at low current densities. The poor efficiency of this reaction is related to the formation of organometallic complexes on the electrode surface that accelerate the rate of hydrogen evolution.