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

Citation

Torelli, Daniel Anthony (2018) The Discovery of Novel Materials for the Electrocatalytic Reduction of Carbon Dioxide. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/RBD5-B141. https://resolver.caltech.edu/CaltechTHESIS:05292018-142628914

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.

Thesis Files