First-Principles Study of Fe₂O₃-Doped Graphene: Structural, Electronic, Magnetic and Optical Insights

Abstract

This study presents a comprehensive theoretical investigation into how iron (III) oxide (Fe₂O₃) doping alters the structural, electronic, optical, magnetic and thermodynamic properties of graphene. A finite-size C52 graphene cluster was used to simulate localised doping effects using Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT). The introduction of Fe₂O₃ significantly reduced the bandgap to ~1.6 eV and introduced mid-gap states, indicating enhanced semiconducting behaviour and reactivity, as confirmed by highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO–LUMO) gap and density of states (DOS) analyses. Optical simulations revealed increased absorbance in the visible spectrum, with characteristic peaks at 310 nm and 395 nm linked to Fe-graphene hybrid orbitals. Magnetic property analysis revealed increased anisotropy and shielding near Fe and O atoms, indicating the formation of localised magnetic moments. Structurally, Fe–C and Fe–O bonds formed stably, with minimal lattice distortion. Vibrational and thermodynamic analyses confirmed increased thermal stability and lower formation enthalpy. The novelty of this work lies in employing a finite-cluster DFT/TD-DFT model that captures localised Fe–O–C interactions and anisotropic magnetic behaviour, which are often overlooked in periodic systems. This integrated approach simultaneously explains the structural, electronic, and optical coupling mechanisms in Fe₂O₃-doped graphene, providing molecular-level insights consistent with experimental observations but previously unquantified theoretically. These findings highlight the potential of Fe₂O₃-doped graphene in optoelectronic devices, photocatalysis, spintronics and energy-related applications.