Quantifying nanosheet graphene oxide using electrospray-differential mobility analysis.

We report a high-resolution, traceable method to quantify number concentrations and dimensional properties of nanosheet graphene oxide (N-GO) colloids using electrospray-differential mobility analysis (ES-DMA). Transmission electron microscopy (TEM) was employed orthogonally to provide complementary data and imagery of N-GOs. Results show that the equivalent mobility sizes, size distributions, and number concentrations of N-GOs were able to be successfully measured by ES-DMA. Colloidal stability and filtration efficiency of N-GOs were shown to be effectively characterized based on the change of size distributions and number concentrations. Through the use of an analytical model, the DMA data were able to be converted into lateral size distributions, showing the average lateral size of N-GOs was ∼32 nm with an estimated thickness ∼0.8 nm. This prototype study demonstrates the proof of concept of using ES-DMA to quantitatively characterize N-GOs and provides traceability for applications involving the formulation of N-GOs.