TAGRA 2024

The development of novel gas sensing materials that operate effectively at room temperature is crucial for improving environmental monitoring systems, particularly the sensitive detection of carbon dioxide (CO₂). Europium oxide (Eu₂O₃) has potential as a sensing material but lacks sufficient sensitivity, stability, and response time at room temperature, making it insufficient for real world application. The objective of this research is to improve CO₂ detection capabilities in ambient circumstances by systematically incorporating graphene dopants into Eu₂O₃ thick films. In addition to an undoped Eu₂O₃ gas sensor and thick film sensors with different graphene concentrations of 0.1%, 0.5%, 1%, 2%, and 5% by weight were fabricated by the screen-printing method on Kapton substrates. The gas sensors were characterised using Field Emission Scanning Electron Microscopy (FESEM) for morphological assessment, Energy Dispersive X-ray EDX for compositional analysis, Raman spectroscopy laser for structural evaluation, and X-ray Diffraction (XRD) for crystallographic analysis. The gas sensors performance were evaluated in a controlled environment laboratory, with CO₂ detection performed at concentration of 30, 50, and 70 sccm under conventional room temperature. The purpose of this study is to determine the best graphene concentration that maximizes sensors reaction time, recovery characteristics, detection sensitivity, repeatability, hysteresis and stabilty. The 2% Eu₂O₃/Gr gas sensor exhibited the best performance, with a low resistance of 0.0874 GΩ and improved responsiveness to CO₂ at 30, 50 and 70 sccm CO₂ concenterations with values of 2.40, 2.37 and 2.34. The 2% Eu₂O₃/Gr sensor demonstrated a 2.1-fold gain in sensitivity, a 4.5-fold improvement in resolution, and a 2.2-fold decrease in standard deviation with linearity 98.04% compared to undoped Eu₂O₃ sensors. Graphene large surface area and high conductivity facilitate CO₂ adsorption and charge transfer between Eu₂O₃ and CO₂ molecules, resulting in enhanced production of carbonate species through redox reactions with Eu³⁺ ions. The ideal graphene doping level was found to be 2%, which balanced the structural integrity of the Eu₂O₃ gas sensors with conductivity increase. In a nutshell, this research demonstrates that graphene doped Eu₂O₃ thick films provide a viable method for room temperature CO₂ gas detection, with increased stability, sensitivity, and response times. Further research into graphene concentration and fabrication methods will give quantitative insights into the link between dopant concentration and sensing performance, assisting in the development of effective, room-temperature CO₂ sensors for industrial and environmental applications.