Preparation And Properties Of Polyaniline-noble Metal Nanocomposites

Conducting polymers and their composites have significant application in catalysts, Li-ion battery, electromagnetic shielding materials, chemical sensors etc. It has been recognized that a metal ion having a higher reduction potential than that of a conducting polymer can be chemically reduced by the conducting polymer. Based on the reductive character of polyaniline (PANI), synthesize the composites of PANI and noble metal such as gold and silver through chemical reduction methord. The effects of technique parameters such as the method of the fabrication of the PANI film, the kinds of the doped acid, conductive additive on the morphology and the performance of the metal are discussed. The morphology and performance of the products were charactered by X-ray diffraction (XRD), Scanning Electronic Microscope (SEM), Energy Dispersive Analysis of X-ray, (EDAX), Surface-Enhanced Raman Scattering (SERS). The following results can be summarized:The rusults showed that three-dimensional Ag can be fabricated on PANI membrane, but the surface of the PANI membrane can not be covered completely. After pre-fabricated gold on PANI membrane, only choose citric acid as dopant uniform and well covered Ag can be fabricated. Citric acid pre-dopped PANI membrane can improve the coveration of the Au and Ag on the PANI membrane, the elaborate structures of Ag are more obvious, but still leaving a some surface of PANI membrane uncovered which can affect the SERS performance of the products. The places of nucleation of Ag on the PANI membrane are increased after 5 mass%conductive additive was added in the PANI membrane, and the coveration is improved at the same time. It is worth to point that uniform and three-dimensional Ag can be fabricated while choose citric acid and mandelic acid as dopant, and strong SERS signal of Rho-damine B can be obtain on these products.The coveration of Ag on PANI film is better than that on the PANI membrane, uniform Ag was fabricated which have a lot of holes between Ag nanoparticles which is good for the enhancement of SERS when choose critric acid and mandelic acid as dopant. Especially strong and unifom SERS signal can be obtain when choose mandelic acid as dopant. Ag structure obtained on PANI film is similar with that on the PANI film which adds conductive additive.Selecting Ag obtained on PANI film when choose mandelic acid as dopant as SERS base test the capacibility of SERS of 20 mg/L, 10 mg/L, 5 mg/L of Rho-damine B, Sudan ? and melamine. Results show that all of the Raman peak can be enhance by this SERS base, strong SERS signal can be obtained while the concentration of Rho-damine B is only 5mg/L. While for the other two adsorbents only some Raman signals can be enhance by this base, respectively at 1593 cm^-1and 678 cm^-1, Raman test can be used to low to 5 mg/L Sudan I and melamine.