Functionalized graphene quantum dots with ZnO as a humidity sensor

Graphene quantum dots (GQDs) are a cutting-edge zero-dimensional (0D) material with a distinct electrical characteristic. The band gap of GQDs can be tuned due to functionalization by function group and/or metal oxides depending on the application. In this study, the impact of functionalizing GQDs by ZnO on their humidity-sensing characteristics was investigated. The effects of functionalizing GQDs with ZnO on their electrical properties and responsiveness to humidity were investigated using density functional theory (DFT). The results demonstrate that in the presence of water molecules, ZHEX C54–ZnO enhances the total dipole moment (TDM) and reduces the band gap energy ∆E to 1.921 Debaye and 0.927eV, respectively. As a result, GQDs ZHEX C54–ZnO appeared to be a suitable choice for humidity sensor applications. Furthermore, the adsorption energies for the optimized geometries were estimated to investigate the appropriateness as well as the effectiveness of the GQDs/ZnO complexes for moisture sensing. In addition, the charge transfer was investigated by utilizing molecular electrostatic potential (MESP) for a more in-depth examination of reactivity and sensitivity. For AHEX C42/OZn/2H2O, ZHEX C54/ZnO/2H2O, and ZTRI C46/ZnO/2H2O, the reactivity of the GQDs/ZnO surface for moisture adsorption was observed to be considerably raised. The results showed that the sensing performance of GQDs functionalized with ZnO makes them ideal materials for humidity sensors.