| In addition to the basic properties of nanomaterials,semiconductor nanomaterials have broad application prospects in many fields such as biology,electronics,catalysis,photoelectric conversion and composite materials due to the special optical,electrical and magnetic properties of semiconductors.Under the dual pressure of energy crisis and environmental problems,the development of new semiconductor nanomaterials with excellent characteristics is an important way to solve current dilemmas.This study focuses on titanium-based and iron-based semiconductor nanomaterials which have abundant reserves,simple production process and superior performance and TiO2 nanotube array,Ag-TiO2 nanotube,Ti3+ self-doped Ag-TiO2 nanotube,hydroxyapatite loaded Ag-TiO2 nanotube,Fe2O3 nanotube array,FeS2 nanotube array,Fe2SiS4 nanoparticle,Fe2GeS4 nanoparticle,FeS2 nanoparticle,CaTiO3 nanotube array,TiO2 nanotube powder,graphene oxide,reduced graphene oxide and graphene modified TiO2 nanotube powder were prepared by different methods.Based on the physical and chemical characterization of these samples,the effects and mechanisms of the semiconductor nanomaterials used in the fields of biomaterials,photocatalytic degradation of pollutants and photoelectric conversion were studied.The specific research contents and results are as follows:(1)TiO2 nanotube arrays with different diameters were prepared by anodic oxidation method.The biological behaviors of Porphyromonas gingivalis on nanotube coatings were studied by using TiO2 nanotube arrays as culture carrier.The modification effects of nanotube array on the biological properties of bacteria and the potential risks of nanomaterials on bacterial resistance were evaluated.The study found that the biological behavior of bacteria on nanotubes is affected by the hydroxyl radicals generated by TiO2 when it’s irradiated by ultraviolet light.At the same time,the bacteria also exhibits nano-size dependence.The oxidative stress effect induced by TiO2 nanotube can change the structure and fluidity of Porphyromonas gingivalis’ cell membrane.The fusion occurs between the bacterial cells and the plasmid containing the drug resistant gene would migrates,thereby enhancing the drug resistance of the bacteria.In addition,Ag doped TiO2 nanotube arrays were successfully prepared by anodization method using Ag-Ti alloy as precursor.Ti3+ self-doped Ag-TiO2 nanotubes were successfully achieved by electrochemical reduction.Then the hydroxyapatite was successfully deposited on Ti3+ self-doped Ag-TiO2 nanotubes by electrochemical deposition.The study focused on its corrosion resistance as the biomaterial.The study found that the Ti3+ self-doping process can effectively enhance the deposition efficiency of hydroxyapatite on the nanotube coating.Compared with Ag-Ti02 nanotube and hydroxyapatite loaded Ag-TiO2 nanotubes,the polarization curves and electrochemical impedance spectroscopy results showed that hydroxyapatite loaded Ti3+self-doped Ag-TiO2 nanotube have higher corrosion resistance which make it a promising biomaterial.(2)The Fe2O3 nanotube arrays were prepared on iron substrate by anodization method,then FeS2 nanotube arrays were prepared by high temperature vacuum vulcanization method using Fe2O3 nanotube as precursor.Based on the characterization of FeS2 nanotube’s physical and chemical properties,the effects and mechanisms of its light absorption and catalytic property were investigated.Compared with Fe2O3 nanotubes and FeS2 nanoparticles,FeS2 nanotubes exhibit excellent light absorption properties.The light absorlption coefficient reached 4.2 × 105 cm-1 and the indirect forbidden band width was 1.24 eV.The prepared FeS2 nanotube array showed certain adsorption and degradation ability to methylene blue and phenol.Under dark condition,the removal of methylene blue by FeS2 nanotube is mainly due to its adsorption capacity and the catalytic degradation caused by FeS2 oxidation.Under visible light illumination,the oxidation of FeS2 is negligible.The degradation of methylene blue can be mainly attributed to the hydroxyl radicals produced by photocatalytic effect and photosensitization effect of dyes.In addition,the unique tubular shape of the nanotube could effectively enhance the light absorption and provide more sites for the adsorption and catalytic reactions,which would further improve the catalytic performance of FeS2 nanotube.(3)Fe2SiS4 and Fe2GeS4 nanoparticles were successfully prepared by vacuum sintering combined with high energy ball milling.Based on its physical and chemical characterization,the catalytic effect and catalytic mechanism of the heterogeneous Fenton system constructed by Fe2SiS4 and Fe2GeS4 nanoparticles were systematically studied for the first time.Other than that,FeS2 nanoparticles are prepared by high energy ball milling.The catalytic effect and catalytic mechanisms of Fe2SiS4,Fe2GeS4 and FeS2 nanoparticles were compared.The study found that in the heterogeneous Fenton system,the dominant reaction is a series of chain reactions occurring on the surface of Fe2SiS4/Fe2GeS4.In addition,the catalytic performance of heterogeneous Fenton system is affected by the Fe atom density of the material’s dominant crystal plane and material’s stability.(4)Highly ordered CaTiO3 nanotube arrays were successfully prepared by simple hydrothermal method using TiO2 nanotube array as precursor.The effects and mechanisms of hydrothermal condition on CaTiO3 nanotube formation were systematically investigated.On the basis of its physical and chemical characterization,the photoelectrochemical properties of CaTiO3 nanotube were tested and evaluated.The study found that compared with TiO2 nanotube and TiO2 coating,hydrothermally prepared CaTiO3 nanotube has higher photocurrent and photovoltage values.The cyclic/linear voltammetry curve indicated that the specific capacitance of CaTiO3 nanotube is higher than that of TiO2 nanotube and TiO2 coating.At the same time,CaTiO3 nanotube has the most negative current rise corresponding voltage and the highest stable current density.The electrochemical impedance spectroscopy results showed that CaTiO3 nanotube has higher barrier resistance.The Mott-Schottky test showed that the flat band potential of the TiO2 coating,TiO2 nanotube and CaTiO3 nanotube were-0.77,0.04 and-0.32 V,respectively.Compared with TiO2 nanotubes,CaTiO3 nanotubes have higher donor density and stability,which make it a promising alternative material for TiO2.(5)The TiO2 nanotube powder was successfully prepared by hydrothermal method.On the basis of systematically studying the influence of preparation conditions on the morphology of nanotubes,the process parameters and mechanism were optimized and confirmed.The graphene oxide was successfully prepared by chemical oxidation method and the reduced graphene oxide was prepared by a simple hydrothermal reduction method using graphene oxide as the precursor.The graphene-modified TiO2 nanotube powder was successfully prepared by in-situ growth method and its photocatalytic properties and the optimization effect of graphene on TiO2 nanotube were investigated.The study found that the in-situ growth method can produce a composite material which graphene and nanotubes are uniformly combined.Compared with pure TiO2 nanotube powders,appropriate amount of graphene modification is beneficial to improve the light absorption and photocatalytic properties of the composite materials. |
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