Conductivity Of Reverse Microemulsion And Synthesise Nanoparticles In The System

The reverse microemulsion technique is a method for fabricating nanomaterials in W/O microemulsion, where nanopools stabilized by surfactant and cosurfactant molecules can be used as "microreactors". Continuous exchange of the micellar contents through dynamic collisions enables the reactions to proceed. It features a simple experimental setup, easy operation, wide application and controllable size of nanoparticles.This dissertation is concentrated on the preparation of a series of nanomaterials by using chemical and electrochemical methods in W/O microemulsion. The structures, morphologies, properties and applications of the as-prepared Pd nanomaterials were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), cyclic voltammetry (CV) and chronoamperometry. Furthermore, the effects of the components on conductivity of the mixed surfactants reverse microemulsion were also studied. The main points of this dissertation are summarized as follows:(l)P-octyl polyethylene glycol phenyl ether (Triton X-100) was used with cetyltrimethylammonium bromide (CTAB) to form mixed surfactants. Then the microemulsion which was prepared with the mixed surfactants, n-hexane, n-hexanol and ammonium palladium chloride solution, was used as the soft templet to synthesize Pd nanoparticles in one step at room temperature. Compared with the single surfactant reverse microemulsion and aqueous solution, the Pd nanoparticles fabricated in the mixed surfactants reverse microemulsion has better dispersion and electrochemical activity for the oxidation of ethanol in alkaline medium. The corresponding results of chronoamperometry imply that the Pd/CTAB/TX-100has better resistance to poisoning and long-term stability for ethanol oxidation.(2) Based on the ideal conductivity of the mixed surfactants reverse microemulsion, it can be used as soft templet directly in the electrochemistry research. The Triton X-100and CTAB were mixed with n-hexane,n-hexanol and ammonium palladium chloride solution to prepare reverse microemulsion. The obtained system was used in the galvarostatic electrodeposition of Pd nanoparticles coating. The morphology and electrocatalytic capability of the Pd nanoparticles coating were investigated. The results indicate that,compared with the single surfactant reverse microemulsion and aqueous solution, the Pd nanoparticles coating prepared in the mixed surfactants reverse microemulsion exhibit the best electrochemical stability and the most excellent catalytic properties for the oxidation of ethanol in alkaline medium. And the current density and the electrodeposition method have effects on electrocatalytic properties of Pd nanoparticles coating.(3) Triton X-100and CTAB was used with bis(2-ethylhexyl) sulfosuccinate sodiumsalt (AOT) to form mixed surfactants. Then microemulsions were prepared with the mixed surfactants, n-hexane, n-hexanol and water. We studied the effects of interaction between non-ionic and ionic surfactants, temperature, structure of the apolar solvent, concentration of cosurfactant and the volume ratio of water to oil on the conductivity of mixed surfactants reverse microemulsion. Moreover the electrochemical behavior of potassium ferricyanide [K3Fe(CN)6]/potassium ferrocyanide [K4Fe(CN)6] in the system was investigated by CV. The results indicate that the conductivity of the mixed surfactants reverse microemulsion is greatly higher than that of the single surfactant systems. But the conductivity ranges between that of TX-100/CTAB and TX-100/AOT double surfactants system, more than that of TX-100/AOT and less than that of TX-100/CTAB. To change the non-ionic surfactant weight ratio, temperature, concentrations of water and cosurfactant have significant effects on the conductivity of mixed surfactants reverse microemulsion.The CV result shows that the redox peak potentials of Fe(CN)63-/Fe(CN)64-/-are almost constant with the change of scan rate, and the redox potentials gaps are about67mV in the mixed surfactants reverse microemulsion. Furthermore, the ratios of redox peak currents at all scan rates are close to1. The oxidation peak current increases linearly with the square root of scan rate. The electrochemical reaction of Fe(CN)63-/Fe(CN)64-is reversible and is controlled by diffusion in the system.