Tuning the electronic structure of graphene oxide through functionalization and doping: A physicochemical, spectral, and catalytic study

Graphene (G) is one of the most promising materials, offering remarkable electrical conductivity and a highly delocalized π-electron system. Graphene oxide (GO) is formed by oxidizing graphene to introduce functional groups that disrupt the sp² carbon lattice and enhance its chemical reactivity. GO exhibits limitations such as a lack of stability during reactions, poor electrical conductivity and limited accessibility of active sites. To overcome these, GO was treated with ammonia and doped with heteroatoms (N, P, S and Si), thereby introducing defects and active functional groups into the carbon lattice. This functionalization and doping enhance its catalytic properties by improving charge transfer, active site density, and surface reactivity. The density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were conducted under the B3LYP/6-31G+(d,p) basis set to investigate physicochemical and optoelectronic properties. MD (Molecular dynamic) simulation has been performed using the TIP3 solvation model and the AMBER14 force field theory. The results reveal that, heteroatom incorporation into aminated graphene oxide significantly reduces the HOMO-LUMO energy gap which facilitates efficient interfacial charge transfer to reactants, while rendering the Gibbs free energy more negative, indicating improved thermodynamic stability. Additionally, the increasing dipole moment and Molecular electrostatic potential mapping reveal more polarized regions that serve as optimized electrophilic and nucleophilic active sites for substrate binding. The phosphorus (P) and sulfur (S) co-doped structure exhibited superior properties due to the lowest band gap, and the most negative Gibbs free energy. MD simulations demonstrate that S mono-doped and P, S co-doped structure maintain structural integrity, steady RMSD, controlled local reconstruction, and increased SASA, ensuring maximum exposure of active sites and catalyst durability during reactions. This study offers a simple yet powerful route to engineer mono-doped and co-doped aminated graphene oxide structures, paving the way for the development of high-performance catalytic materials.