Electrochemical carbon dioxide capture via mineralisation or reduction

Since the start of the industrial revolution, global temperatures have risen by approximately 1 °C. The human population is now starting to notice the effects of this change. Polar ice caps are melting at an ever faster rate,[1] flooding[2] is becoming more commonplace and wildfires are repeatedly raging across more parts of the globe.[3] The temperature rise has been correlated with increases in atmospheric carbon dioxide (CO2) levels. Researchers are attempting to find routes to capture CO2 for permanent storage or to upgrade it for use as valuable chemical feedstocks. Electrochemical CO2 capture methods are attractive owing to their ability to harness renewable energy sources such as solar energy. In Chapter 2, a technology for achieving carbon capture and mineralisation using aqueous electrochemistry is described. The conversion of waste metal sources into metal carbonates is explored. The CO2 capture is enhanced by a supercapacitive swing adsorption effect that concentrates carbon dioxide in solution.

As an alternative application, CO2 can be electrochemically reduced with electrons and protons to form valuable feedstock molecules such as carbon monoxide or fuel-type molecules such as ethane. To perform this electrochemistry on an industrial scale, the cathode catalyst must be highly efficient and selective. A novel type of electrocatalyst is synthesised in Chapter 3 using protected diazonium salts to modify a copper electrode, and the resultant materials are tested for their performance in the reduction of CO2 in Chapter 4. Finally, in Chapter 5 a novel strategy for the development of a sub-monolayer modification on an electrocatalyst is explored, this may be another useful tool for designing a new type of organically modified cathodes for electrocatalysis.