(Invited) Electrochemical Reduction of CO2 to Value-Added Chemicals: Status and Remaining Challenges

Abstract

Significant reduction in atmospheric CO2 emissions as well as in the development of alternative energy sources will be critical to curb the unwanted effects of climate change (e.g., global warming, erratic weather patterns) and to reduce our dependence on fossil fuels. A variety of strategies needs to be pursued to curb the increase in atmospheric CO2 level. One potential strategy that can be employed to overcome this challenge is the electrochemical reduction of CO2 into useful chemicals such as formic acid, carbon monoxide, hydrocarbons, or alcohols. To drive thus process in a cost effective manner otherwise-wasted renewable energy that is produced in excess of grid demand can be used. A key challenge is the development of catalyst materials that are active and selective for the electrochemical reduction of CO2, i.e., catalysts that can reduce CO2 at low overpotentials (and thus high energetic efficiency), produce desired products at high current densities over long periods of time, and do so selectively while suppressing unwanted reactions. Most present efforts to re-energize spent CO2 via electrochemical methods struggle to achieve simultaneously high energetic efficiency, high product selectivity, and high throughput. This presentation will provide an overview of progress by us and others in (i) developing suitable cathode catalysts for CO2 reduction (primarily to CO) as well as suitable anode catalysts (typically for the oxygen evolution reaction) needed for a CO2 electrolysis cell; (ii) optimizing operation conditions for these catalysts (pH, electrolyte composition, …); and (iii) developing gas diffusion electrodes suitable for a CO2 electrolysis cells. A projection for the potential for further improvement of catalysts, electrodes, operation conditions, and electrolysis cell designs will be made. Also, a gross margin model to estimate economic feasibility, as well as the results of a techno-economic analysis of a process that converts the CO2 of a 0.5 MW power plant to fuel via electroreduction of CO2 to CO, followed by Fischer-Tropsch will be presented.