Département de chimie moléculaire

The electrocatalytic redn. of carbon dioxide to formic acid on metallic electrodes is known to suffer from low c.d. and rapid surface contamination by electrolyte impurities. Gas diffusion electrodes (GDE) can overcome these problems due to their high sp. surface area. In this work, we show a simple method to prep. indium coated gas diffusion electrodes (GDE-In/C) and their phys. and electrochem. 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 aq. media (dissolved CO2) at -1.65 V vs. Ag/AgCl, the partial c.d. toward HCOOH on the GDE-In/C is 7 times higher than on the indium foil with a faradaic efficiency of 45{%}. The prodn. of formic acid increases by 15{%} when a continuous flux of CO2 gas is applied through the GDE-In/C. In addn., 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 electroredn. [on SciFinder(R)]