Enhancing the Electrochemical Surface Area of Tin Based Porous Electrodes for Carbon Dioxide Reduction to Formate

Conversion of CO₂ to value added chemicals can provide an attractive alternate pathway for making petrochemicals without petroleum based raw materials, storing renewable energy in chemical form, as well as providing greater acceptance to CO₂ as a valuable resource of chemical manufacture. This work deals with the electrochemical reduction of CO₂ to formate / formic acid, with specific focus on economic feasibility of this process. The current density or rate of production of product directly affects the overall capital expenditure of a large scale process by affecting the reactor requirements. In this paper, the various approaches studied to enhance the electrochemical surface area of the electrodes will be presented. Electroplating of tin of carbon fiber substrates provided a 5-10 times area enhancement. Nano particles of tin (~ 5 nm size) were formed on high surface area activated carbon black (Vulcan XC-72).  The porous electrode structure is optimized based on the binder content and loading on the base substrate. Studies were also performed to ascertain the effects of tin oxide on the reduction of CO₂ to the desired product. The time evolution of the performance of such electrodes with respect to both, the overall current density as well as the selectivity towards formate product will be presented. Characterization of the electrode and particle morphology based on ‘before’ and ‘after’ experiment SEM and TEM analysis will also be presented.