Bandgap engineering in graphene oxide (GO) via integrating DFT calculations with atmospheric-pressure microplasma (AMP) treatment for optoelectronic applications

Atmospheric-pressure plasma (AMP) is a simple, fast, cost-effective, and environmentally friendly technique used to reduce graphene oxide (GO). This process involves exposing GO to AMP for a specific duration, creating a reactive environment that partially reduces GO. Density functional theory (DFT) simulations and experimental investigations using Ultraviolet-Visible (UV-Vis) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, and Scanning Electron Microscope (SEM) were used to analyze the structural, electronic, and optical properties of GO and rGO, focusing on enhanced control over reduction extent and band gap modification. DFT calculations show that GO has a tunable band gap due to oxygen functional groups. Simulation results show GO, monolayer of GO, and graphene exhibit band gaps of 4.775 eV, 1.9 eV, and 0 eV, respectively, indicating tunable properties of GO in terms of density of states, dielectric components, coefficient of absorption, and coefficient of conductivity. UV-Vis’s spectroscopy uses Tauc's plots to estimate the band gap and assess electronic characteristics. Initially, GO has a wide band gap (4.773 eV), narrowing to (1.1-1.2 eV) post-reduction. FTIR results show that GO exhibits insulting characteristics due to -OH functional groups, undergoes SP 3 hybridization transformation, and with increasing reduction times becomes changing into highly conducting rGO, which exhibits SP 2 hybridization. SEM data shows that exposure time regulates GO reduction, transforming irregular structures into hexagonal planes and improving particle grain size. This research proposes a novel technique for efficient GO reduction to comprehend plasma reduction processes and highlight GO potential for optoelectronic applications.