Dipole moment effects in dopamine/N-doped-graphene systems

Abstract

In the present work the effect exerted by N-doping on parameters characterizing dopamine adsorption on modified graphene substrate is theoretically studied. Moreover, an analysis of dipole moment properties of dopamine/N-doped-graphene system was performed in order to predict the feasibility of N-doped graphene system as a sensor material. Dopamine molecule anchors preferentially according to parallel modes of adsorption, stabilizing predominantly through dispersive interactions and showing very small atomic charges. On the other hand, the anchoring on sites with one nitrogen atom in the carbon monovacancy border is much more favored than on other sites, owing to non-covalent hydrogen bonding interactions. An analysis carried out about the modifications of polarization along the normal direction to the basal planes of graphene-based substrates, considering the most representative parallel modes of dopamine adsorption, indicated that N-doping enhances such dipole moment changes, compared with regular graphene, particularly when dopamine anchors on N-graphitic defects with four nitrogen atoms as impurities and N-pyridinic defects with one impurity nitrogen atom.