Electrocatalytic reduction of carbon dioxide on indium coated gas diffusion electrodes-Comparison with indium foil

The electrocatalytic reduction of carbon dioxide to formic acid on metallic electrodes is known to suffer from low current density and rapid surface contamination by electrolyte impurities. Gas diffusion electrodes (GDE) can overcome these problems due to their high specific surface area. In this work, we show a simple method to prepare indium coated gas diffusion electrodes (GDE-In/C) and their physical and electrochemical characterization. Indium is chosen for its ability to reduce CO2 to formic acid at relatively low overpotential compared to other metals. The catalytic performance of the GDE-In/C is compared to an indium foil using identical operating conditions. During electrolysis in homogeneous aqueous media (dissolved CO2) at -1.65 V vs. Ag/AgCl, the partial current density toward HCOOH on the GDE-In/C is 7 times higher than on the indium foil with a faradaic efficiency of 45%. The production of formic acid increases by 15% when a continuous flux of CO2 gas is applied through the GDE-In/C. In addition, the GDE-In/C shows a good resistance to electrolyte impurities and allows to achieve higher current densities. These promising results are a key milestone in the development of a zero gap cell for gas phase CO2 electroreduction. (C) 2016 Elsevier B.V. All rights reserved.