Transition Metal-Based Complexes and Organic Small Molecules for the Electrochemical Reduction of Carbon Dioxide and Dioxygen"

The current primary source of energy for mankind, fossil fuels, is non-renewable and is the major source of anthropogenic carbon dioxide (CO2) emissions that are negatively impacting the environment. There remains a need to develop alternative energy sources that are not harmful towards the environment while meeting the increasing global energy demands. One approach is to utilize electrochemical methods, using electricity generated from renewable energy sources like solar or wind, to drive forward key energy reactions such as the reduction of CO2 and dioxygen (O2). Imperative to this process is developing electrocatalysts capable of lowering energy barriers associated with these reactions. The major advantage molecular systems offer in contrast to heterogenous systems is that key intermediates can be observed, and therefore crucial mechanistic steps can be identified. Furthermore, molecular catalysts can be easily modified to obtain better results by simply switching out different metal centers or altering the ligand backbone. We have investigated inorganic (nickel polypyridyl complex) and organic (Cyclic (Alkyl)(Amino) Carbenes) species competent in mediating the electrochemical conversion of CO2. Additionally, we characterized a known water-soluble catalyst, Mn(III) mesotetra(N-methylpyridinium-4-yl)porphyrin, through the entire pH domain and found it capable of reducing O2 to water under buffered acidic conditions.