The Discovery of Novel Materials for the Electrocatalytic Reduction of Carbon Dioxide

Abstract

The removal of atmospheric carbon dioxide is likely the only route to mitigating the effects of decades of increased fossil fuel combustion. Artificial photosynthesis presents one method for removal and conversion of problematic carbon dioxide into chemically useful products. By coupling electrochemical CO2 reduction (CO2R) to a renewable energy source atmospheric CO2 could be converted back into a fuel such as ethanol, or a commodity chemical such as ethylene. These products could then be consumed for energy or used to generate plastics effectively removing CO2 from the atmosphere. Significant advances in current electrocatalysts are needed in order for large scale CO2R to become a reality. Most known catalysts are only capable of transferring 2 electrons with needed protons to CO2 producing either carbon monoxide or formic acid. Copper is the only known metal capable of reducing CO2 to hydrocarbons at appreciable rates and low overpotentials. This work aims to find new materials that produce similar hydrocarbons, but at lower overpotentials with higher rates and greater selectivity than current copper catalysts. By implementing a cyclic process referred to as the Catalyst Discovery Cycle (CDC) iterations between predications, catalyst testing, and active site characterization allow for the rational design and discovery of new and improved catalysts. This methodology led to the discovery of nickel-gallium bimetallics as low overpotential catalysts for CO2R to methane, ethylene, and ethane. In addition, theoretical and experimental observations have determined a proposed active site and side reactions detrimental to their activity.