Polyaniline coated graphene hybridized SnO^sub 2^ nanocomposite: Low temperature solution synthesis, structural property and room temperature ammonia gas sensing

An inorganic-organic hybrid of SnO2-reduced graphene oxide (rGO)-polyaniline (SGP) nanocomposite has been successfully synthesized from surfactant-free precursor by a low temperature solution process. The SGP nanocomposite is found to form from in situ synthesized SnO2-rGO (SG) and polyaniline (PANI), generated via polymerization of aniline monomer at 5–10 °C. The structural properties of SGP have been analyzed by X-ray diffraction, transmission electron and atomic force microscopes. The chemical interaction existed in the nanocomposite has been examined by X-ray photoelectron, Fourier transform infrared and Raman spectroscopies. Compare to pristine SnO2 and SG, the SGP sample shows an enhanced ammonia gas sensing at room temperature. At an optimum content of PANI, high sensitivity, fast response and good selectivity of the gas sensing are observed in the nanocomposite. This enhanced sensing performance can be attributed to well-defined p-n hetero junction formation in the hybridized polyaniline and rGO with nano SnO2 in SGP as confirmed from structural characterization of the sample. It is also seen that the presence of PANI layers in SGP, enhances the chemical stability as reflected from the observation of negligible decrease in the sensing performance of sample up to 30 days period. This facile process can create an avenue for development of various metal oxide semiconductor-graphene-polyaniline nanocomposites for improving room temperature stable ammonia gas sensor.