Enhanced CO₂ Sensing by Oxygen Plasma-Treated Perovskite–Graphene Nanocomposites

Carbon dioxide (CO₂) is a major greenhouse gas responsible for global warming and climate change. The development of sensitive CO₂ sensors is crucial for environmental and industrial applications. This paper presents a novel CO₂ sensor based on perovskite nanocrystals immobilized on graphene and functionalized with oxygen plasma treatment. The impact of this post-treatment method was thoroughly investigated using various characterization techniques, including Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The detection of CO₂ at parts per million (ppm) levels demonstrated that the hybrids subjected to 5 min of oxygen plasma treatment exhibited a 3-fold improvement in sensing performance compared to untreated layers. Consequently, the CO₂ sensing capability of the oxygen-treated samples showed a limit of detection and limit of quantification of 6.9 and 22.9 ppm, respectively. Furthermore, the influence of ambient moisture on the CO₂ sensing performance was also evaluated, revealing a significant effect of oxygen plasma treatment.