Tuning electronic properties of graphene nanoribbons for enhanced detection of toxic gases (F₂, AsH3, PH₃ and HF): A density functional theory study

This study investigates the potential of graphene nanoribbons (GNRs) with zigzag and armchair edge configurations as highly sensitive sensors for toxic gases (F₂, AsH3, PH₃, and HF) using density functional theory (DFT) with the B3LYP/6-31G basis set to model and optimize the geometric and electronic structures of pristine and gas-adsorbed GNR compounds. The electronic, structural, and adsorption properties of these GNRs were analyzed to evaluate their gas-sensing performance. Results reveal that zigzag-edged GNRs exhibit superior sensitivity due to their localized edge states, which significantly alter electronic properties upon gas adsorption, particularly for F₂, as evidenced by a notable reduction in the energy gap (from 1.22 eV to 0.97 eV). Meanwhile, armchair paradigms display stable electronic structures with smaller band gap fluctuations (~0.5 eV). This means that the armchair-edged GNRs demonstrate greater stability and selectivity, with minimal changes in their electronic structure, suggesting robust sensor performance under ambient conditions. Adsorption energy calculations and infrared spectra further highlight the distinct interactions between the gases and GNRs, with zigzag edges showing stronger responses. Additionally, descriptors such as chemical hardness, softness, electronegativity, and dipole moment provide insights into the reactivity and polarizability of the systems. The findings suggest that zigzag GNRs are promising candidates for high-sensitivity gas sensors, while armchair GNRs may be better suited for robust and selective detection applications. This work contributes to the optimization of graphene-based sensors for environmental and industrial toxic gas monitoring.