Improving the Performance of a NO2 Gas Sensor Using a TFB-polymer and Graphene Composite: A Comparative Study with an H2S Sensor

Abstract

This study investigates the performance of a gas sensor based on composites of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine)] (TFB) polymer and graphene (Gr) for the detection of nitrogen dioxide (NO₂) and hydrogen sulfide (H₂S). The sensor was fabricated by spin-coating mixtures of TFB and Gr at various volume ratios onto glass substrates with aluminum electrodes. The structural and morphological properties of the films were characterized using X-ray diffraction (XRD) and atomic force microscopy (AFM). The gas sensing performance was evaluated at different operating temperatures (50–200°C). The results demonstrate that the sensor’s performance is highly dependent on the TFB:Gr mixing ratio and temperature. The optimum sensitivity for NO₂, an oxidizing gas, was 64.4%, achieved at a 5 : 1 mixing ratio and an operating temperature of 150°C. In contrast, the highest sensitivity for H₂S, a reducing gas, was 60%, observed at a 5 : 1 ratio and 100°C. The TFB:Gr composite sensor exhibits superior performance for NO₂ detection at elevated temperatures, with the 5 : 1 ratio providing an optimal balance between the polymer’s gas interaction sites and graphene’s conductive pathways.