Open circuit voltage (OCV) experiments were used to confirm no gas leakage in the system (Figures S9.1, S10.1, S11.1 & 17.1). In the future, more stable quinone molecules and carbon supports could reduce the amount of degradation seen within the system. Further experiments were run between 0 to -2.5 V with a 10-minute voltage hold after each cycle to allow maximum adsorption (Figure ). From the initial cycles, f-CMK-3 had an adsorption capacity of around 1 mmol g -1 , which rapidly decreased upon cycling, presumably due to degradation processes (see below). After the system began to stabilise, the adsorption capacity leveled to around 0.4 mmol g -1 , similar to what is seen for a limited cell voltage range of -1 to -2 V, but this larger voltage window proved more energy intensive, exhibiting a higher energy consumption of 830 kJ mol -1 . Additionally, a steeper negative pressure slope for this larger voltage window suggests increased material degradation (Figure Interestingly, control experiments on the unfunctionalized carbon, u-CMK-3, also showed a small amount of reversible CO2 capture with an initial adsorption capacity of 0.15 mmol g -1 when cycled within a -1 to -2 V window (Figure .3), which is higher than what is seen under N2 atmosphere (Figure .2). It can be assumed that some redox-active functionalities are present on the u-CMK-3 surface, shown by a high oxygen content in elemental analysis and XPS (Table .1 and Table .1). These functionalities are likely to only give broad features in the CV experiments, indistinguishable from the double-layer capacitance, but may contribute to electrochemical CO2 capture when anthraquinone is not present. This unexpected electrochemical CO2 adsorption may also be due to the carbon electrode polarization causing enhanced CO2 physisorption. This would not be seen under N2 due to the lack of polarizability. The difference in adsorption capacity between f-CMK-3 and u-CMK-3 was assigned to grafted anthraquinone-around 0.2 mmol g -1 -confirming grafting of anthraquinone on CMK-3 improves carbon adsorption.