【作者】 陆希峰；

【导师】 王琪珑； 崔得良；

【作者基本信息】 山东大学 ， 无机化学， 2009， 博士

【摘要】 1989年,美国科学家Liu和Cohen从β-Si₃N₄的结构出发,利用固体体弹模量的经验计算公式,从理论上预言β-C₃N₄的硬度可以和金刚石相媲美,同时指出该材料还具有一系列独特的力学、光学和摩擦性能。这一预言引起了物理学家、化学家和材料学家的兴趣和广泛关注。此后,许多实验和理论工作相继展开,对这种材料及其同系物进行了系统的探索研究。本文首先综述了氮化碳的晶体结构、研究历史和现状。在已有工作的基础之上,我们提出了一种新的合成氮化碳和进行性质研究的思路,并进行了比较系统的工作:我们首次提出了一种新的恒压溶剂热合成方法,并将其应用于可控制备氮化碳材料的探索研究中,初步探讨了其中的温度和压力反应参数。在该体系中,我们以三氯代嗪（C₃Cl₃N₃）作为碳、氮源,以盐酸肼（N₂H₄·2HCl）作为氮化剂,制备了石墨型氮化碳纳米晶,实验条件分别为40 MPa,220、250、280℃和280℃,50、80、120 MPa。结果表明,反应温度和反应体系的压力对产物的结晶质量和形貌具有重要影响。探索了模板方法在氮化碳纳米晶和纳米管合成中的应用。用介孔分子筛（SBA-15）表面为模板,以三氯代嗪（C₃Cl₃N₃）作碳、氮源,NaN₃作氮源,N,N-二甲基甲酰胺作溶剂;恒压溶剂热法（300℃）制备了C₃N₄纳米晶。分子筛的引入提高了产物的产率、结晶度,展现了分子筛表面羟基的配位-催化作用和表面吸附作用。此外,以多孔氧化铝（AAO）作模板,结合溶胶-凝胶高温聚合（600℃）制备了石墨型氮化碳纳米管。用常规的三电极体系在0.5 mol·dm^-3 H₂SO₄和0.5mol·dm^-3 H₂SO₄+1 mol·dm^-3 CH₃OH中对氮化碳纳米管的稳定性和电化学性质进行了研究。实验结果显示,该物质对甲醇氧化表现出一定的催化活性和良好的稳定性。以三氯代嗪（C₃Cl₃N₃）和三聚氰胺（C₃N₆H₆）作原料,通过氮气气氛下的固相反应（300℃）制备了石墨型氮化碳,并对其结构和组成进行了表征。同时,利用循环伏安法和充放电曲线对该物质的电化学性能进行了研究;结果表明,该材料具有一定的嵌锂能力,但比容量低、循环寿命短。本文通过在饱和的硝酸锂、硫酸镁、硫酸铝以及硝酸钾、硫酸钾溶液中电解实现阴、阳离子的可控嵌入;并通过控制电解时间来实现对石墨相氮化碳片层电子云密度的控制,从而制备片层中具有不同电子云密度的石墨型氮化碳插层化合物。采用XRD、FTIR、XPS、TEM和TG对产物的结构、组成、形貌和热稳定性进行了表征;我们提出了石墨型氮化碳插层化合物的结构模型,并尝试用离子-π作用解释了插层前后物质的结构变化。最后,我们以钛酸四丁酯和g-C₃N₄的前驱物（溶胶-凝胶）的混合物为前驱物,采用水解法和高温煅烧制备了N掺杂TiO₂的g-C₃N₄/TiO₂复合物纳米微粒,利用X射线衍射（XRD）和X射线光电子能谱（XPS）等技术对所得产物进行了表征,并考察了g-C₃N₄/TiO₂催化剂在紫外光和可见光下光催化降解罗丹明的性能。总之,本论文的工作为氮化碳的合成、性质研究和应用提供了重要的理论意义和应用价值。更多还原

【Abstract】 In 1989, Liu and Cohen proposed a hypothetic covalent carbon-nitrogen compoundβ-C₃N₄, on the basis ofβ-Si₃N₄ structure. According to this formula and on the basis of theβ-Si₃N₄ structure, the authors have claimed that it might have bulk modulus and hardness comparable to that of diamond. Then C₃N₄ has attracted considerable interest and attention from physicists, chemists and materials scientists, due to its unique mechanical, optical and tribological properties. Intensive experimental and theoretical investigations of C₃N₄ and other derived polymorphs have been performed.In this thesis, the literature related to research history, crystal structure and research state of carbon nitride are reviewed. Based on the reported work, a novel way to research on carbon nitride is proposed and systematic investigations have been carried out The major results are as follows:We firstly develop a new route called constant-pressure solvothermal synthesis, which is used in the synthesis of carbon nitride. In this reaction system, the reaction parameters, i.e., reaction temperature and pressure factors have been primarily discussed. Herein, graphite-like C₃N₄ （g-C₃N₄） nanocrystals have been synthesized by the reaction between C₃N₃Cl₃ and N₂H₄·2HCl. The process was carried out at 40 MPa （220,250,280℃） and 80℃（50,80,120 MPa）, respectively. The results indicate that the temperature and the pressure play an important role in affecting the crystalline perfection and morphology of C₃N₄ products.The application of template-assisted method in the synthesis of carbon nitride nanocrystals and nanotubes has been explored. Herein, mesoporous molecular sieves （SBA-15） are used as the template. Nanocrystals of C₃N₄ have been prepared via the reaction of C₃N₃Cl₃ with NaN₃ at 300℃in DMF solution through constant-pressure solvothermal method. The introduction of SBA-15 improved yield and crystallinity of the desired products, indicating the functions of surface adsorption and coordination-catalysis of hydroxyls. In addition, carbon nitride nanotubes （CNNTs） have been synthesized with porous anodic aluminum oxide （AAO） membrane as template by the thermal polymerization of sol-gel precursors （600℃）. Measurement on stability and electrochemical performance of carbon nitride nanotubes are carried out in 0.5 mol·dm^-3 H₂SO₄ and 0.5 mol·dm^-3 H₂SO₄ + 1 mol·dm^-3 CH₃OH in the conventional three electrodes system. The experimental results show that the nanotubes are stable and electrocatalytic for methanol oxidation to an extent.Graphite-like carbon nitride （g-C₃N₄） was prepared in large quantities at 300℃under nitrogen via the reaction of C₃N₃Cl₃ with NaN₃ by a solid-state reaction route, of which the structure and the composition were characterized. The electrochemical properties of g-C₃N₄ were studied using both cyclic voltammetry and charge-discharge recycling. It was found that the g-C₃N₄ sample showed certain reversible intercalation capacity of Li⁺, but the capacity was small and the recycling time was short. Furthermore, the intercalated carbon nitrides with Li⁺, Mg²⁺, Al³⁺, SO₄^2- and NO₃^2- as guest ions were prepared by electrolysis of carbon nitride powder in the saturated solution of lithium nitrate, magnesium sulfate, aluminum sulfate, potassium nitrate and potassium sulfate. In the experiments, the electron density within the layers was adjusted by changing the intercalation time, and the corresponding intercalation compounds were obtained. The structure, composition, morphology and thermal stability of intercalation compounds were characterized by X-ray powder diffraction （XRD）, Fourier transform infrared spectra （FTIR）, X-ray photoelectron spectroscopy （XPS）, transmission electron microscopy （TEM）, and thermogravimetry （TG）. The possible structure model of intercalation compounds is proposed. The cation-πinteractions and electrostatic interactions are used to explain the changes of microstructure and chemical bonds before and after intercalation.At last, g-C₃N₄/TiO₂ composite was prepared by hydrolysis of tetrabutyl titanase and the precursors of g-C₃N₄ at room temperature and annealing in nitrogen atmosphere. The structure and the composition of g-C₃N₄/TiO₂ were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and so on. The photocatalytic activity of g-C₃N₄/TiO₂ composite for the UV and visible-light degradation of Rhodamine B was studied. In summary, the experiment results presented here provide useful information on the synthesis, property, and application of carbon nitride.更多还原