Modern society faces a number of crucial challenges regarding energy and the environment. Firstly, the amount of carbon dioxide (CO2) entering the environment must be reduced to minimise its negative effects on global warming and ocean acidification. Secondly, advances in energy storage are required so that energy from intermittent, renewable sources are not wasted when produced in excess. In recent years, many efforts have been devoted to developing carbon capture, storage and utilisation technologies in order to address both of these issues simultaneously. One such example of CO2 utilisation is in the electrochemical CO2 reduction reaction (CO2RR), where CO2 is converted into energy dense, transportable fuels, using water and electrical energy. This conversion of CO2 into fuels, such as ethylene, ethanol or methane, involves the formation of new chemical bonds, which store significant amounts of energy. Therefore, using renewable energy sources (e.g. solar, wind, tidal etc) to power this process ultimately results in the storage of electrical energy in the form of chemical bonds, which can be reclaimed through existing combustion infrastructure. Electrocatalysts are materials that are responsible for facilitating the chemical processes in the CO2RR and determine the reaction outcome.
Copper is the only known pure metal that can convert CO2 into multicarbon products, such as ethylene and ethanol, which are highly desirable as they are more energy dense and have a much higher value than C1 products. One significant problem of using copper in the CO2RR is that 18 different products can be formed, and so more sophisticated materials based on copper are required to target specific products. The objective of this project was to synthesise organic molecules (ligands) that can be anchored onto the surface of a copper catalyst in order to fine-tune the CO2RR towards a more favourable outcome. These ligands would contain an imidazolium functional group that is well known to interact with CO2 molecules, which might concentrate CO2 molecules at the copper surface and increase the activity of the catalyst. The research carried out in this project concluded that indeed, functionalising metal surfaces with imidazolium ligands is a powerful tool for directing the outcome of the CO2RR.
