Theoretical Investigation of the Adsorption Behavior of Caffeine, Nicotine, and Dopamine Molecules Using 2D Monolayers

Previous research on caffeine has shown it to have positive effects while also causing certain diseases; nicotine has been proven to have many adverse effects and is highly addictive; and dopamine is a key neurotransmitter but can also bring complications to human health. The adsorption behavior of caffeine, nicotine, and dopamine molecules on boron nitride, graphene, and silicene monolayers was systematically investigated using first-principles calculations based on density functional theory (DFT). The optimized atomic structures, adsorption energies, charge transfer distributions, and band structures were analyzed to evaluate the adsorption behavior of these molecules and the 2D monolayers. Results show that adsorption on boron nitride and graphene is generally weak with dopamine exhibiting the strongest interaction among the three molecules. In contrast, silicene demonstrates significantly stronger adsorption for the three molecules with notable reductions in adsorption distance and substantial modifications to its electronic structure, including the opening of small band gaps for caffeine and nicotine. The inclusion of van der Waals corrections was found to be critical, consistently enhancing the adsorption energies across all systems. Overall, silicene emerges as the most promising candidate for the adsorption of caffeine, nicotine, and dopamine, which paved the way to explore new functional materials.