Electronic Structure and Charge Transfer Mechanisms of Nucleobase–Pd–Graphene Complexes: DFT Exploration

This study investigates the electronic structure and charge transfer behavior of nucleobase (guanine and adenine)–palladium–graphene (DNA–Pd–Gr) complexes using density functional theory (DFT) as a computational framework. As biomolecular interactions with metal‐decorated graphene surfaces play an increasingly significant role in nanoelectronics and biosensing applications, understanding their fundamental electronic characteristics is essential. In this work, the charge transfer, HOMO–LUMO energies, density of states (DOS), and dipole moment were calculated to identify the nature and extent of electronic coupling within the complexes. The findings reveal that adsorption of both nucleobases reduces the HOMO–LUMO gap (HLG) of Pd‐doped graphene, leading to enhanced electrical conductivity. The results demonstrated that when the nucleobases guanine and adenine were adsorbed on the Pd‐doped graphene surface, guanine exhibited stronger interaction due to its higher polarizability and multiple binding sites. The adsorption leads to noticeable changes in the electronic properties of the graphene sheet, including a reduction in the HLG and localized charge redistribution near the Pd site. These findings provide insight into the molecular‐level mechanisms governing metal‐facilitated biomolecule adsorption on graphene, offering potential implications for the development of graphene‐based biosensors, molecular electronics, and nanodevices.