PhD transfer exam | Lindsey Daniels, Modeling the Interaction of Graphene with a Liquid Electrolyte

Modeling the Interaction of Graphene with a Liquid Electrolyte

Unlike other areas of graphene applications, the theoretical modeling of graphene based biochemical sensors lags significantly behind experimental work.  In these applications, graphene operates in a field effect transistor configuration, where its surface is in contact with a liquid electrolyte. By applying a gate potential, one may control the electrical conductance of graphene, which is highly sensitive to the presence of adsorbed ions, ion concentration and the pH of the electrolyte. Modeling of the electrostatic interactions of the system will be done using well-established models from electrochemistry, which generalize the Poisson-Boltzmann equation taking into account the finite size of ions, as well as two modifications of the dielectric constant of the solvent due to dielectric saturation in strong electric fields and due to excess ion polarization.  In the long term plan, the effects of pH on the system will be analyzed using site-binding theory, which will also be used to study the competitive binding of protons and salt ions from the solution.