In-situ synthesis and characterization of reduced graphene Oxide and sulfonated graphene-polypyrrole nano-composites for use in gas sensor

Design and development of gas sensors with high sensitivity and selectivity is very important. Among conducting polymers, polypyrrole (PPy) is a promising material having excellent environmental stability, high intrinsic electrical conductivity, low cost and easy synthesis. PPy and its composite with carbon nanotube (CNT) and other metal oxide have shown very attractive gas sensing applications, but graphene is preferred over CNT due to its larger sensing area per unit volume and high electron mobility at room temperature. In this study, graphene oxide (GO) was synthesized from natural graphite powder by a modified Hummers method [1] and was reduced by hydrazine. Graphene derivatives such as reduced graphene oxide (RGO) and sulfonated graphene (SRGO), will be synthesized in nano-sized dimention. The polypyrrole-graphene derivatives hybrid nano-composites were synthesized via in-situ oxidative polymerization of pyrrole. Characterization of graphene-based conducting polymer composites will be done by variety of spectroscopy techniques. According to appropriate solubility of The RGO/PPy and SRGO/PPy composites in organic solvents such as chloroform, the electrospinning technique was used to coate it onto a Cu-IDE surface as chemiresistor gas sensor [2]. In order to evaluate the gas sensing properties of nanocomposites, the electrical resistance and dielectric properties were measured in the presence of different concentration of ammonia and alkyl amines. In the following, the sensing behavior of the SRGO/PPy were compared to RGO/PPy nanocomposite. A typical response of RGO/PPy sensor to ammonia gas at different concentration shown in Fig.1.