| With an increasing demand on membrane materials with specific functionalities, the research on inorganic-inorganic and organic-organic composite films has drawn an ever greater attention in the science and technology fields. The synergism of inorganic, organic molecules and metallic nanoparticles in the film show various unique properties typical of their components; for instance, an addition of an organic component could compensate the fragileness of inorganic material and raise its flexibility. Tailoring material with both ingredients and component ratio may result in a composite film with outstanding performance in optic, electric, magnetic and catalytic areas.TiO2 nanotube array films with a large aspect ratio and high specific surface area, characteristic of a hollow structure and an easiness to be modified, grow perpendicularly on matrix, and transit electrons conveniently and quickly inside their nanotube array, resulting that electrons cannot be easily annihilated and they can transit easily onto matrix. In addition, nanotube array scatters light less than nanoparticles or orderless nanotubes, and has a larger light absorption in comparison, which shows an extensive application in photoelectrochemistry and catalytic fields. TiO2 nanotube array is characterized as wide valence band semiconductor material, which means a difficult electron transition between valence band and conduction band, i.e. electron transition can be realized as a result of UV light absorption in photocatalysis and photoelectric conversion. Recently extensive work has been carried out in modification areas like decreasing the valence band, widening absorption spectrum, and improving performance of TiO2 nanotube array. The experimental section is mainly on the preparation of TiO2 nanotube array film via anodic oxidation and subsequent doping modification by semiconductor nanoparticle.In addition, polyoxometalates, with a fascinating structure, specific constitution, high symmetry, thermal stability, good conduction and storage for electrons and protons, as well as good solubility in polar solvents, have drawn wide attention in photo, electro, magnetic, catalytic and biologic chemistry. Traditional polyoxometalates are inorganic compounds with a large molecular mass as well as structures difficult to alter, and their size, shape and physicochemical properties are difficult to be tailored in application. Large amount of research shows that many polyoxometalates with novel structures and specific properties can be obtained through decoration. The research trend lies in the synthesis of novel functional materials with different performance. Organic compounds, with excellent molecular tailoring and decorating capabilities, are widely used in decorating modification of polyoxometalates and preparation of polyoxometalates-organic composite materials with a variable structure and performance of both inorganic and organic compounds. The organic decoration of polyoxometalates alters their physicochemical properties, facilitates their additional assembly, and expands their application, which constitutes to be a major topic in the study of polyoxometalates chemistry. Polyoxometalates film materials with organic decoration have an improved surface property and capabilities in photo, electro and catalytic chemistry.Electrochemistry is a branch of physical chemistry that studies chemical reactions taking place at the interface of an electrode, usually a solid metal or a semiconductor, and an ionic conductor, the electrolyte. These reactions involve electric charges moving between the electrodes and the electrolyte (or ionic species in a solution). Thus electrochemistry deals with the interaction between electrical energy and chemical change. Electrochemical analytical methods are a class of techniques in analytical chemistry which study an analyte by measuring the potential (volts) and/or current (amperes) in an electrochemical cell containing the analyte, which were introduced by a German chemist C. Winckellel in 19th century. They are widely used in bioelectrochemistry, electrochemical detectors or sensors in energy and materials section, and spectroelectrochemistry with advantages like easy operation, high accuracy and wide application.This work is based on the preparation and characterization of TiO2 nanotube array films and polyoxometalate{Mo72Fe3o} based inorganic-inorganic or inorganic-organic doping materials in surface properties, photoelectrochemical and/or electrocatalytical properties.This paper is made up of four chapters:Chapter I is consisted of an introduction of research background, topic selection principle and main content of this work.In chapter II, Ag2S/CdS/Ti02 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor-Ag2S (0.9 eV) quantum dots (QDs)-in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs fabricated by uniformly depositing the QDs into the TNTs via the successive ionic layer adsorption and reaction (SILAR) method were synthesized, respectively. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) results demonstrated that the Ag2S/CdS/TNTs prepared by SSM and other films were successfully prepared. In comparison with the four films of TNTs, CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs by SILAR, the Ag2S/CdS/TNTs prepared by SSM showed much better absorption capability and the highest photocurrent density in UV-vis range (320-800 run). The cycles of local deposition have great influence on their photoelectric properties. The photocurrent density of Ag2S/CdS/TNTs by SSM with optimum deposition cycles of 6 was about 37-fold that of TNTs without modification, demonstrating their great prospective applications in solar energy utilization fields.In chapter III, Mo72Fe3o-PDA-Ag composite material was prepared by using polyoxometalates{Mo72Fe3o}, dopamine chloride and silver nitrate under non-alkaline conditions. The Mo72Fe3o-PDA-Ag composite material was then dropped onto pretreated ITO conduction glass surface due to the strong adsorption of dopamine on solid surface. Later the Mo72Fe3o-PDA-Ag composite material modified ITO electrode was used in electrocatalytic reaction with IO3". X-ray powder diffraction, UV-vis spectroscopy, SEM, TEM and XPS studies were used in characterization of Mo72Fe3o-PDA and Mo72Fe3o-PDA-Ag composite materials. Results show that the dopamine (DA) was polymerized into polydopamine (PDA) and globular aggregates of composite materials were obtained under acid conditions with a variable size in relative to the dosage of dopamine chloride. Mo72Fe3o-PDA-Ag composite materials were resulted from the reduction of silver nitrate with Mo72Fe3o-PDA. Ag nanoparticles were deposited on the surface of the Mo72Fe3o-PDA via in-situ reduction by polydopamine. Electrochemical work shows Mo72Fe3o-PDA-Ag modified ITO glass electrode has a good electrocatalytic capability in reduction of IO3-.In chapter IV, the work describes the preparation and hydrophobic behavior of self-patterning porous films consisting of giant vesicles formed by a 2.5-nm-diameter, polyoxometalate (POM) cluster{Mo72Fe3o} macroanion and a double-tailed cationic surfactant dimethyldistearylammonium bromide (DODMABr) in CHCI3-CH3OH mixture solvent (VCHC13:VCH3OH= 3:1). These inverse vesicles with the diameter in the range of 0.45～1.30μm in organic solution and the porous films consisting of the giant vesicles of the{Mo72Fe3o}(DODMA)3 complexes were characterized by SEM, TEES. and AFM observations. Self-patterning of these giant vesicles into porous films which are highly ordered honeycomb films on solid surfaces can survive drying as the frameworks are firstly studied in detail. Water contact angle measurements confirmed that the porous films of{Mo72Fe3o}(DODMA)3 vesicles were endowed with hydrophobic properties from the hydrophilic surface. This porous film materials consisting of giant vesicles may be promising new options in many fields like photoelectrochemistry, sterilization, template, catalysis, in-situ synthesis, etc. |
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