The cell voltage window was limited by the stability of the electrolyte therefore two full reduction peaks could not be obtained. This suggests the quinone loading reported above is an underestimation of the amount of AQ present. Indeed, a simple estimation of the anthraquinone loading based on the sample mass increase following functionalisation gave a higher value of 22 ± 7 wt. % (see experimental). This means that we cannot rule out the presence of some electrochemically inactive anthraquinone in f-CMK-3. We also explored further techniques to explore the incorporation of anthraquinones in f-CMK-3, including EDX (Table .1), XPS (Table .2) and TGA, (Figure .1)). However, accurate quantification of anthraquinone loading from these techniques was not possible. Ultimately, we believe the electrochemical techniques are the best method to determine quinone loading as they indicate the quantity of quinone that is electrochemically accessible and therefore would partake in an electrochemical carbon capture process.