Interfacial Phenomena Governing Performance of Graphene\nElectrodes in Aqueous Electrolyte

There is evidence\nof the presence of intercalated water between\ngraphene and the substrate in electronic devices. However, a proper\nunderstanding of the impact of this phenomenon, which causes important\nlimitations for the optimization of graphene-based devices operating\nin aqueous electrolytes, is missing. We used graphene-based electrodes\non insulating and conducting substrates to evaluate the impact of\nintercalated water by combining experimental techniques with numerical\nsimulations. Results show that the capacitance of the conductive substrate/graphene\nelectrodes is significantly higher than that of the insulating substrate/graphene\nones. Meanwhile, Raman spectroscopy demonstrates that graphene charge\nmodulation with the applied potential is independent of the substrate\nconductivity. We found that this intriguing behavior is influenced\nby the water intercalation phenomena and governed by the substrate\nconductive nature. This work contributes to the understanding of the\nelectric response of graphene-based devices in an aqueous environment\nand of the methods to measure and model it.