UC San Diego

The majority of our energy needs depends on non-sustainable fuels: coal, oil and natural gas. Carbon dioxide that comes from fossil fuels accounts for 65% of greenhouse gas emission that plays a major role in climate change. Therefore, the development of an alternative carbon cycle that includes production of sustainable fuels should be the priority for the future of our planet. The electrochemical CO2 reduction is a promising pathway from both economic and environmental points of view. The main challenge to implement this technology at an industrial scale is to find the catalyst that will be robust, selective with high conversion efficiency. This thesis described multiple approaches to solving this problem. One of the most effective electrocatalytic systems for the electrochemical reduction of CO2 to CO was described in Chapter 2 of this thesis, where Re(tBu-bpy)(CO)3Cl molecular catalyst was incorporated into the structure of MWCNTs and obtain all advantages of both homogeneous and heterogeneous catalysis. This system is considered to be one of the most selective and robust among other developed CO2 electroreduction systems. This heterogeneous system was developed under the support of NASA/JPL as an alternative for the current technology that is being tested on planet Mars, where the CO2 gas represents 90-95% of the Martian atmosphere. The Mars Oxygen In-Situ Resource Utilization Experiment is better known as MOXIE reduces CO2 to CO and produces Oxygen gas that is vital for supporting human life during the interstellar missions. This device utilizes yttria-stabilized zirconia and operates at 700C. Thus, the development of an alternative electrochemical device that operates at room temperature is of a great interest and a serious challenge. Chapter 2 of this thesis describes the main breakthrough in the development of a key part of this device that represents the cathode at which selective CO2 reduction to CO occurs. The development of the anode that will electrochemically produce O2 and building a complete device are among future challenges.