New Catalysts for Electrochemical Reduction of CO2

The concentration of carbon dioxide (CO2) in the atmosphere continues to rise having reached the highest level in recorded history five years ago and this is driving the rise in global temperatures. The utilization of CO2 either directly from the atmosphere or from stored sources is currently attracting attention as a promising approach to mitigate both energy and environmental issues and the electrochemical conversion of CO2 into high quality chemical feedstocks and fuels is one way to do this. This thesis focused on the development of tetrapyrrolic molecule-based electrocatalysts for the selective and efficient conversion of CO2 into CO at low overpotential. Initially a range of metallotetraphenylporphyrins were screened to determine which metal centre had good catalytic activity for CO2 reduction. Fe tetraphenylporphyrin showed the highest catalytic activity compared to other metal centres. The best performing Fe tetraphenylporphyrin was then utilised to optimise the use of different proton sources in homogeneous catalysis using a DMF electrolyte. Two different proton sources (water and trifluoroethanol) were added into the Fe porphyrin catalytic solution and higher catalytic activity was observed in the presence of trifluoroethanol. Therefore, trifluoroethanol was employed as the primary proton source for further investigations.