Sensing the quantized reactivity of graphene

Highlights: • Cq of single-layer graphene was successfully measured by impedance spectroscopy. • Cq variations are quantized as a function of the environmental changes and can be correlated with chemical reactivity. • The variation in chemical hardness or softness can be tracked in situ by measuring the Cq of graphene. • Cq reflects the quantized sensitivity of graphene to the environment and its quantized sensing properties. • SLG can be used as an in situ sensing tool for the reactivity of a molecule with its environment. • The chemical reactivity of graphene with its environment was interpreted using first-principles conceptual DFT. We demonstrated that the variations measured in the quantum capacitance of single-layer graphene, envisioned here as a conceptual molecular model, depend on the chemical reactivity of the molecule and can be used as an analytical and sensing tool for environmental conditions. The variations are quantized as a function of the environmental changes and can be correlated with chemical reactivity indexes such as chemical hardness and softness. This not only constitutes a proof-of-principle that the chemical reactivity of graphene, as a single molecule, can be determined in situ by measuring the quantum capacitance, but also that these measurements can be used as an analytical tool.