Highly selective and sensitive chemiresistive NO₂ sensor using reduced graphene oxide/metal-base porphyrin composite

Prolonged exposure to nitrogen dioxide (NO₂) poses significant risks to human health, including respiratory and cardiovascular diseases. To address this challenge, we developed a high-performance sensor device utilizing the metal-based porphyrin 5,10,15,20-Tetraphenyl-21H,23H-porphine manganese (III) chloride (Mn-TPP) as a functional modifier for reduced graphene oxide (rGO). This composite material capitalizes on its exceptional chemiresistive properties for the effective detection of NO₂. Graphene oxide (GO) was synthesized using the Hummers method and thermally reduced to produce rGO. Mn-TPP was subsequently functionalized onto rGO to form the composite, which was thoroughly characterized using structural (XRD), spectroscopic (FTIR, UV-Vis, Raman), electrical (I-V), and morphological (AFM) methods to validate its composition and properties. A simple drop-casting method was employed to fabricate the sensor device on a copper-coated microelectrodes at glass substrate. The sensor exhibited outstanding real-time performance for NO₂ detection at room temperature (24ºC), achieving a notable limit of detection (LOD) of 1 ppm. Additionally, it demonstrated rapid response and recovery times of 31 s and 20 s, respectively. The sensor also showcased excellent stability over 50 days, along with high repeatability and reproducibility, establishing it as a promising candidate for practical NO₂ gas sensing applications in environmental monitoring, industrial safety, and public health management.