In the search for new quinone-based electrodes for electrochemical carbon dioxide capture, we were inspired by previous work on the covalent functionalisation of carbon electrodes for energy storage applications. Quinone functionalisation provides additional energy storage capacity through Faradaic processes, adding to the initial capacity of the carbon from non-Faradaic electrochemical double-layer capacitance. The use of a covalent attachment between quinone molecules and the carbon backbone prevents the dissolution of the redoxactive molecule into the electrolyte, increasing the cycle life of the electrode. Furthermore, this attachment ensures facile electron transfer to and from grafted molecules. A popular approach for covalently attaching quinones to activated carbon is to use the spontaneous diazonium radical reaction. This well-understood reaction allows a range of materials to be investigated, as the reactions are tolerant to a diverse set of quinones and conductive carbon materials, and only require an inexpensive radical initiator to be stirred with the activated carbon material and quinone molecule present in solution. Quinone-functionalised activated carbons have previously been reported as improved energy storage materials, however, they