Single graphene nanoplatelets: capacitance, potential of zero charge and diffusion coefficient†
Nano-impact chronoamperometric experiments are a powerful technique for simultaneously probing both the potential of zero charge (PZC) and the diffusion coefficient (D0) of graphene nanoplatelets (GNPs). The method provides an efficient general approach to material characterisation. Using nano-impact experiments, capacitative impacts can be seen for graphene nanoplatelets of 15 μm width and 6–8 nm thickness. The current transient features seen allow the determination of the PZC of the graphene nanoplatelet in PBS buffer as −0.14 ± 0.03 V (vs. saturated calomel electrode). The diffusion coefficient in the same aqueous medium, isotonic with many biological conditions, for the graphene nanoplatelets is experimentally found to be 2 ± 0.8 × 10−13 m2 s−1. This quick characterisation technique may significantly assist the application of graphene nanoplatelets, or similar nano-materials, in electronic, sensor, and clinical medicinal technologies.