Electrochemical reduction of CO 2 to formic acid on Bi 2 O 2 CO 3 /carbon fiber electrodes

Electrochemical reduction of CO 2 to formic acid is a good strategy to address both environmental and energy issues. However, some drawbacks including low activity, selectivity, and stability of electrocatalysts must be overcome. We propose a method for tailoring Bi 2 O 2 CO 3 -coated carbon fiber electrodes with higher selectivity and stability for electrochemical CO 2 reduction to formic acid. We evaluated the effect of Bi 2 O 2 CO 3 and Nafion contents on the electrocatalysts performance for CO 2 reduction reaction (CO 2 RR). All electrodes produced only HCOO − in the liquid phase with a maximum faradaic efficiency (FE) of 69%. The electrocatalysts were stable under 24 h of continuous CO 2 RR operation. The FE increased with the increasing electrolyte concentration and cation radius size, which indicates that the anion stabilization in solution is critical for adequate formate generation. The CO 2 RR mechanism was proposed with basis on the literature. The structural carbonate of Bi 2 O 2 CO 3 acts as an intermediate species in the formate production from CO 2 .