Electrochemical conversion of CO2 to formic acid utilizing Sustainion™ membranes

Formic acid generated from CO2 has been proposed both as a key intermediate renewable chemical feedstock as well as a potential chemical-based energy storage media for hydrogen. In this paper, we describe a novel three-compartment electrochemical cell configuration with the capability of directly producing a pure formic acid product in the concentration range of 5-20 wt% at high current densities and Faradaic yields. The electrochemical cell employs a Dioxide Materials Sustainion(TM) anion exchange membrane and a nanoparticle Sn GDE cathode containing an imidazole ionomer, allowing for improved CO2 electrochemical reduction performance. Stable electrochemical cell performance for more than 500 h was experimentally demonstrated at a current density of 140 mA cm(-2) at a cell voltage of only 3.5 V. Future work will include cell scale-up and increasing cell Faradaic performance using selected electrocatalysts and membranes.