Studies On The Preparations And Applications Of Polypyrrole And Sulfide Cadmium Nanomaterials

Having a serial of unique physical and chemical properties, nanomaterials are prospecting to be applied in many fields. However, it is still a challenge to get a large amount of nanomaterials with controlled size cheaply. Therefore, study on the preparation of nanomaterials is one of the most pressing tasks at present.Polypyrrole is especially promising for commercial applications because of its good stability, facile synthesis and higher conductivity than many other conducting polymers. However, under usual conditions polypyrrole is insoluble and infusible, which restrict its processing and applications. The emergence of molecular conductive wire also makes it important to synthesize polypyrrole nanowires. Polyporrole nanowires were synthesized electrochemically on the graphite electrodes in aqueous solution within a few minutes even decades of seconds. The experimental results demonstrated that polypyrrole nanowires grow with two-dimensional instantaneous nucleation process and one-dimensional growth pattern. The appearance of the polypyrrole nanowires is affected by polymerization potential, electrochemical method, pyrrole and electrolyte concentration and polymerization time. Polypyrrole nanowires could be synthesized only when the polymerization potential is between 0.75 V and 0.95 V. Polypyrrole nanowires with diameters 40 nm～150 nm were synthesized by controlling the synthetic conditions. FTIR spectra of the polypyrrole nanowires shows that the intrinsic conductivity decreases with the increase of the polymerization potential and the highest intrinsic conductivity is 186 S/cm. The conductivity of the polypyrrole film with nanowire morphology was measured using the device designed by ourselves. This conductivity is three orders lower than polyporrole intrinsic conductivity.The application of the polypyrrole nanowire modified electrode in the pH sensor was studied. The results showed that the film thickness has no affect on the pH potentiolmetric response of the film, so it is easy to make pH sensors with the same response. The effect of synthetic conditions on the pH response was studied. In order to further understand the process and phenomena that determine the performance of the polypyrrole nanowire film as a pH sensor, the pH potentiolmetric response mechanism of the polypyrrole nanowire film was studied and a formulation that fits this mechanism has been established. The catalytic performances of polypyrrole nanowires during hygrogen evolution reaction were also studied, so as the metal (respective Fe, Ni, Cu) /polypyrrole nanowires composite electrodes. It was revealed that they all had better electrocatalysis than graphite electrode.Here, the preparation of CdS semicondutor nanoparticles was studied too. CdS semicondutor nanoparticles have been attracting much attention in the recent years for its outstanding luminescence and photoelectricity translating properties. In this work, CdS nanoparticles were prepared by using SHCH2COOH as the stabilizer. UV-Vis absorbance spectrum and transmission electron microscopy (TEM) were successfully employed to evaluate the size of the CdS nanoparticles. The size and stability of the particles are affected by the preparation conditions such as reaction temperature, concentration of SHCH2COOH and pH of the solution. CdS nanoparicles with diameter 2.4 nm were prepared at room temperature in a solution with pH=9.0 and the value HSCH2COOH/S2-=3.5. The size distribution of the CdS nanoparticles is ±5% with a long-time stability.