When supporting electrolyte matters - tuning capacitive response of graphene oxide via electrochemical reduction in alkali and alkaline earth metal chlorides

The ability to tune charge storage properties of graphene oxide (GO) is of utmost importance for energy conversion applications. Here we show that electrochemical reduction of GO is highly sensitive to the cations present in the solution. GO is reduced at lower potential in alkali metal chloride solutions than in alkaline earth metal chlorides. During the reduction, capacitance of GO increases from 10 to 70 times. Maximum capacitances of reduced GO are between 65 and 130 F g-1, depending on the electrolyte and the presence of conductive additive. We propose that different interactions of cations with oxygen functional groups of GO during the reduction are responsible for the observed effect.