Synthesis of polypyrrole nano/microspheres using cobalt(III) as an oxidizing agent and its ammonia sensing behavior

Polypyrrole (ppy) has been synthesized by employing [Co(NH 3 ) 6 ]Cl 3 as a new oxidizing agent under basic condition in aquous solution. The optimized ratio of monomer to oxidizing agent has been taken as 1:2. The reaction was allowed to continue for 24-48 h at room temperature. The as synthesized ppy displayed well defined morphology, which was seemed as time dependent. It was nanospheres at 24 h, micro/nano mixture at 36 h and microspheres and microfibers at 48 h. The FTIR confirmed the formation of ppy due to the presence of characteristics broader ring and N-H stretching vibrations. The XRD showed the development of crystallites only within the fibrous ppy. The thermal and structural correlation was determined using TGA and DSC techniques alongwith SEM. The polymer was found to be considerably more stable as compared with similarly synthesized using other such oxidants. The conductivity of pure polymer and effect of NH 3 over its conductivity was analyzed by four probe technique. Its strong potential of NH 3 sensing has been confirmed from this technique due to showing linear increase in its conductivity. These results demonstrated that cobalt(III) is a potential oxidizing agent to produce thermally stable nano/microspheres of ppy. Moreover, the material was found quite useful for its characteristics of NH 3 sensing that can be applied for other nitrogenous bases.