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

Abstract

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