Conductivity and interaction mechanism of polydopamine-graphene oxide: a combined experimental and density functional theory investigation

Composites comprising polydopamine (PDA) and graphene oxide (GO) exhibit notable electrical conductivity; however, research on the interaction between dopamine (DA) and GO remains limited. In this study, we employed a simple and environmentally friendly method to prepare and characterize this composite material, optimizing the ratio of DA to GO in the process. Our findings that when the mass ratio of DA to GO is 1:2, the composite demonstrates enhanced electrical conductivity. Furthermore, density functional theory (DFT) calculations were utilized to elucidate the influence of various oxygen-containing functional groups on the DA adsorption process onto GO. Parameters such as adsorption energy, charge differential density, energy gap, and energy barrier were primarily evaluated. Our results indicate that the reduction of GO by DA predominantly targets the epoxy group, leading to improved conductivity. Conversely, the presence of the epoxy group significantly undermines the adsorption between DA and GO, thereby compromising stability. In contrast, functional groups like carboxyl, hydroxyl, and carbonyl enhance the adsorption energy to varying extents. Notably, when the density of hydroxyl groups on the GO surface reaches a specific threshold, the adsorption energy experiences a significant decline. In summary, the type and quantity of oxygen-containing functional groups on GO exert a considerable influence on its interaction with DA. This research offers valuable insights for the selective preparation and application of these composites.