Significance of different dopamine species as reducing agents of graphene oxide: Fundamental aspects

Abstract

Nowadays, the production of reduced carbon by means of chemical procedures is an economic alternative of relatively easy implementation. To this purpose, the use of a catecholamine as dopamine has been considered an attractive option, because, in addition to the fact that dopamine is an environmentally friendly compound, it has the capability to generate a surface coating on reduced graphene oxide, favoring its applicability in composite materials. In the present DFT approach, the reduction process of graphene oxide model surfaces taking into account four different dopamine species as reductants and different routes for dissociation reactions were explored, particularly those due to catechol and amine groups of dopamine species. Our results indicate that the zwitterionic and protonated species exhibit stronger adsorbate-substrate bonding strength as well as larger reactivity, compared with neutral and deprotonated ones. This behavior can be attributed to a higher electron transfer to the substrate. Different mechanisms for a complete graphene oxide reduction have been explored. The routes involving the amine group of dopamine are more favored than those through a catechol group. The results of this DFT approach are of special value for the research on dopamine coatings.