Dopamine-mimetic functionalized three-dimensional graphene prepared by 3D printing: Multiscale investigation from macroscopic performance to DFT-driven interfacial mechanisms

To effectively address the potential threats posed by microplastics (MPs) to the environment and human health, this study drew inspiration from the naturally occurring biocompatible substance dopamine. We prepared poly(dopamine) (PDA)-modified graphene oxide (GO) ink and successfully constructed a poly(dopamine)-functionalized graphene macro-adsorption network (3DGO/PDA) via direct ink writing (DIW) printing technology. The incorporation of PDA significantly enhances the adsorption active sites of 3DGO/PDA, endowing it with outstanding adsorption performance toward polystyrene (PS) microspheres. Concurrently, the exceptional three-dimensional network pore structure of 3DGO/PDA provides efficient mass transfer pathways and abundant pore space for the adsorption and storage of polystyrene. Experimental results indicate that under pH= 5 conditions, 3DGO/PDA3 achieves an 86 % (PS initial concentration of 200 mg/L, temperature of 313.15 K) removal rate for polystyrene, maintaining stable adsorption performance after multiple cycles. Density functional theory (DFT) calculations indicate that the adsorption of PS onto the adsorbent involves a synergistic interaction of multiple mechanisms, with amino-dominated chemical adsorption playing a dominant role. Therefore, by combining the functionalization design of polydopamine with 3D printing technology and leveraging density functional theory calculations at the electronic level, the enhanced adsorption mechanism was systematically elucidated. This provided new design ideas and a theoretical basis for the development of efficient microplastic adsorption materials.