The above results indicate that by adding EWGs we are simultaneously making electrochemical reduction more favourable and carbon capture less favourable, supporting the early work of DuBois. Therefore when designing quinone derivatives for electrochemical CO 2 capture to enhance efficiency, a balance between favouring electron transfer and chemical steps must be taken into account. Focusing on the EEC scheme of the Fsubstituted AQ series, this trade-off can be seen clearly by combining Figures C against the shift in E • EE , as shown in Figure (a). The shifts are plotted relative to the unsubstituted AQ and regions where each step is favoured or disfavoured are colour-coded accordingly. The linear solid blue trend line that emerges confirms the unfavourable relationship between the thermodynamics of cathodic activation and nucleophilic addition of CO 2 .