▎ 摘　　要

A new nanocomposites series of polypyrrole/reduced graphene oxide (PPy/rGO) and polypyrrole/reduced graphene oxide covalently bonded with aryl 4-carboxybenzene diazonium salt (PPy/rGO-aryl-COOH) were prepared by simple one-step chemical oxidative synthesis. Spin coating technique was used to deposit the as-prepared nanocomposites on BOPET substrate for testing their chemiresistive sensitivity properties towards online detection of (NO2) vapors at ambient temperature. The recorded morphological and structural data confirmed that PPy/rGO-aryl-COOH forms a homogeneous nanocomposite within the size of 80 nm and improvement of the crystalline ordering. PPy/rGO-aryl-COOH revealed the optimal NO2 sensing properties in terms of higher sensitivity (1.01%/ppm), faster response time (129 s), detection limit of (2 ppm), and reproducibility. Moreover, stability was tested under humidity and temperature effects. Finally, impedance spectroscopy is conducted in the fresh air and in the presence of gas. These results highlight the paramount role of functionalization of reduced graphene oxide (rGO-aryl-COOH) in improving both the sensitivity and the reactivity of our produced nanocomposite regarding NO2. Strong interaction between the NO2 gas molecules and the aryl-COOH-functionalized rGO has dramatically enhanced the electronic properties of these nanocomposites. These striking characteristics of the newly developed nanocomposites make them very suitable for NO2 gas sensing.