| By using the depersive phase of the reverse microemulsion as a micro-reacter or a template, nano-materials with various structure and morphology can be obtained from microemulsion. Nano water-pools in the reverse microemulsion are independent and the materials in water-pools transits after the collision of water-pools, which made nanoparticles to be systhesized. However, this synthesis method can only prepare single nanoparticle and can't prepare functional materials at the appointed surface of electrode. Electrochemical technique as an effective synthesis and analysis approach has attracted much attention in many fields including energy transform, biology, and metallurgy and corrosion science etal. Traditionally, aqueous solution, organic solution and molten salt are used as electrolytes for electrochemical reaction. Reverse microemulsion that is characterized by low conductivity is not used as an electrolyte yet.In this text, a good conductive water-in-oil (W/O) microemulsion composed of p-octyl polyethylene glycol phenyl ether (Triton X-100), n-hexanol, n-hexane and water solution with high concentration hydrochloric acid was prepared. K3Fe(CN)6 was added in as a water-soluble electroactive probe, and its electrochemical behavior was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was found that the increases of the HCl concentration in the water phase will increases the on the conductivity of the W/O microemulsion, and hence influences the electrochemical behavior of K3Fe(CN)6. When HCl in the water phase is 0 mol?L-1 (the pH of water phase is about 7), the conductivity of the W/O microemulsion is only 1.2μS?cm-1, and K3Fe(CN)6 almost can not react at the glassy carbon (GC) electrode. But when the HCl concentration is more than 3 mol?L-1, the W/O microemulsion has good conductivity and K3Fe(CN)6 shows good electrochemical performances in it. The results of CV and EIS studies indicate that the electrochemical behavior of Fe(CN)63-/Fe(CN)64- in the W/O microemulsion is a quasi-reversible process and is controlled by both diffusion and charge transfer, which is different from that in the aqueous solution where the electrochemical behavior of Fe(CN)63-/Fe(CN)64- is a reversible one and is controlled by diffusion only. These results may be due to the unique liquid structure of the W/O microemulsion and the unique mass transfer in the W/O microemulsion. Au nanoparticles coatings were successfully electrodeposited from the electrode/reverse microemulsion system by using the reverse microemulsion composed of Triton X-100, n-hexanol, n-hexane and water with strong-acid gold chloride solution. The electrodeposition process of Au was studied by CV and EIS. The results indicate that the reduction of Au (Ш) is a completely irreversible process, and the impedance of the electrochemical reaction in microemulsion is 5.5 times as high as that in the water solution. The scanning electron microscopy images show that the coatings electrodeposited from the reverse microemulsions are made up of gold nanoparticles with diameter of about 50 nm. The electrochemical reaction activity of the Au nanoparticles modified electrode is higher than that of the pure gold electrode. Due to the large specific surface area, the Au nanoparticles modified electrode has good hydrogen evolution capability in acid solution and good electrocatalytic capability for glycerol oxidation in alkaline media.Additionally, W/O microemulsion, bicontinuous (B.C.) microemulsion and Liquid Crystals (L.C.) systems were successfully prepared by using cetyltrimethylammonium bromide (CTAB) as the surfactant, n-butylalcohol as the cosurfactant, n-octanethis as the oil phase, and NiSO4 and HCl aqueous solution as the aqueous phase. Using these systems above as the electrolytes, special electrochemical systems were also established, and Ni deposits were prepared by electrodepostion. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy were employed to study the cathodic process of Ni2+ in the W/O system, B.C system and L.C. system. The results indicate that the cathodic processes of Ni2+ in the three systems are quite different. The SEM study shows that the Ni electrodepsit prepared from the W/O system is made up of compact nanoparticles with diameter of 60～80 nm, and the Ni electrodepsit prepared from B.C. system is made up of larger particles with diameter of 100~300 nm, while the Ni electrodeposit prepared from L.C. system is quite smooth and there are also a few of Ni nanoparticles with diameter of about 100 nm embedded in the deposit. Due to the different morphologies and specific surface areas, the anodic passive currents of Ni electrodepsitions modified Ni electrodes in H2SO4 solution are quite different. |
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