Interfacial Synthesis Of Au-PANI Nanocomposites For Catalytic Applications

Polyaniline(PANI), with its good machinability, conductivity and stability, is one of the most used conducting polymers, which is used in variety of fields. Au nanoparticles, known as good catalyst, has also drawn much attention for its large specific surface area and high surface energy. Based on the situation, Au-PANI nanocomposites have been a hot research area for several years, as they are a combination of PANI and Au nanoparticles(Au NPs), which show high potential in electric instrument, biosensors and catalytic applications. In this paper, controlled growth and catalytic properties of Au-PANI nanocomposites are studied by experiments.Interfacial polymerization, with a smaller-density oil phase(toluene) than the water phase, was taken to synthesize Au-PANI nanocomposites. By changing temperature and molar ratio of reactants, we have got comparatively good experiment conditions, and two kinds of composites are acquired, with their morphology and nanostructure distinguished. Lollipop-like Au-PANI nanocomposites were acquired when HAu Cl4 is at a low use level, while nanospheres were synthesized at a relatively high use level. The concentration of HAu Cl4 is 10 mmol/L during preparation of Au-PANI nanocomposites. Catalytic study indicates that lollipop-like Au-PANI nanocomposites have high catalytic ability for reduction of 4-nitrophenol into 4-aminophenol by Na BH4. Notably, the lollipop-like nanostructure is most efficient and can finish the catalytic reaction in about 12 min. Further experiments were carried out to test catalytic stability of these catalysts, and the results shows that lollipop-like Au-PANI nanocomposites are good catalysts with high catalytic stability for reduction of 4-nitrophenol by Na BH4. Moreover, we find Au-PANI nanocomposites are good nanoreactors for Surface-enhanced Raman spectroscopy(SERS) monitoring plasmon-driven reactions under laser exposure at a wavelength of 633 nm.N-Methyl pyrrolidone(NMP) was used to have Au-PANI nanocomposites immersed in it, and the structure and morphology of the nanocomposites have changed at different time. The result indicates that with the immersing time getting longer, the lollipop-like nanostructure was destroyed, for the reason of dissolve of PANI in solution of NMP, which result in much more exposure of Au nanoparticles. Yet, its catalytic ability for reduction of 4-nitrophenol into 4-aminophenol by Na BH4 was improved, and Au-PANI nanostructures show excellent catalytic performance in this reaction after immersed in NMP. Within 5 min, this reaction can be finished, which is owned to large surface area of Au nanoparticles exposed on the surface of Au-PANI nanocomposties. However, under laser exposure at a wavelength of 633 nm, none of their catalytic properties are improved in Surface-enhanced Raman spectroscopy(SERS) monitoring plasmon-driven reactions.