Electrochemical CO2 reduction is a promising technology for producing carbon-neutral fuels and chemicals using renewable energy, while simultaneously reducing greenhouse gas emissions. However, achieving practical activity requires the development of efficient and selective electrocatalysts to facilitate the CO2 electroreduction. Of the various CO2 reduction products, liquids are ideal due to their high volumetric energy density and high market potential. While several precious and non-precious metals have shown activity for the conversion of CO2 to CO, only copper and copper-based materials have shown the ability to produce small quantities of liquid alcohol products such ethanol and n-propanol, albeit with limited selectivity (&lt;20%). Alternatively, CO reduction on oxide-derived copper catalysts in alkaline electrolytes has produced liquid products with over 65% selectivity, motivating the development of a two-step electrolysis, where CO2 is initially reduced to CO, and CO is then reduced to valuable alcohols. However, efficient CO reduction to alcohols has yet to be demonstrated in a practical flow electrolyzer at high rates (&gt; 1mA/cm2). In this talk, we will present our work in developing an integrated two-stage electrolyzer stack system for the conversion of CO2 to alcohols. The first stage utilizes a state-of-the art nanoporous Ag catalyst in a PEM-based flow cell capable of reducing CO2 to CO with faradaic efficiencies of 96% and partial current densities of 40 mA/cm2 with facile separation of the CO product. For the second stage, a CO reduction flow cell using alkaline electrolyte can reduce CO to liquid products with moderate selectivity (40%), including n-propanol with a faradaic efficiency of 20% at 22 mA/cm2. This work demonstrates the feasible production of multi-carbon alcohols via CO reduction at appreciable rates, and motivates further development of a two-stage electroreduction process of CO2 to alcohols.

Electrochemical carbon dioxide conversion to alcohols

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.