Electrochemical experiments: Cyclic voltammetry measurements were carried out with a standard threeelectrode cell using a BioLogic Sp-150 with BioLogic EC-Lab software. Electrochemical measurements were conducted in a glass cell. The glassy carbon working electrode, platinum wire counter electrode and leak-free Ag/AgCl reference electrode were all purchased from Alvatek. 5 mM Fc was used as the internal standard after the measurements were taken. Tetrabutylammonium hexafluorophosphate in DMSO (0.1 M) was used as the electrolyte. 1 mM of quinone was stirred in electrolyte before gas purging. The solution was purged under N 2 for 2 hours, while stirring. For electrochemical tests with quinones under CO 2 , the electrolyte was bubbled with 100% CO 2 for 2 hours before experiments were run. All the measurements were recorded at a scan rate of 10 mV s -1 .