石墨相氮化碳纳米复合材料的制备与光电化学性能研究

发布时间：2018-03-02 04:29

本文关键词： 光催化异质结纳米片石墨相氮化碳模特-肖特基效应　出处：《湘潭大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着全球环境恶化日益严重,人们对环境污染问题逐渐重视,利用光催化剂将太阳能转化为人类可以直接利用的能量,并用其解决地球资源的枯竭和生存环境的恶化是可再生清洁能源研究的一个重要方向。石墨相氮化碳(g-C3N4)作为一种新型的无污染环保型光电材料,有着广阔的研究空间和应用前景。本文以g-C3N4的纳米复合材料为研究对象,分别通过声化学方法和热缩聚方法合成了三元复合纳米材料g-C3N4/MoS2/GO和g-C3N4/MoS2/Ag。我们对合成的复合材料进行成分、结构、形貌、光学特性等进行表征,通过对样品的瞬态光电流响应测试和交流阻抗测试表征其光电化学性能,通过光催化降解RhB溶液进行了光催化性能表征。而且,基于表征和测试结果对合成的三元复合材料进行了光生电子空穴转移、分离和光催化机理分析。本文以g-C3N4纳米复合材料的研究结果为界面的异质结和原位耦合助催化剂的半导体催化材料设计和大规模生产提供了参考。主要结果如下:(1)通过简易的声化学方法制备了g-C3N4/MoS2/GO。制备的三元复合纳米材料中超薄MoS2纳米片和GO纳米片大范围地提高了可见光的吸收性能,进而促进三元复合纳米材料产生更多的光生电子。MoS2纳米片与GO纳米片和石墨相氮化碳耦合,在g-C3N4/Mo S2和g-C3N4/GO界面形成两类P-N异质结,这些异质结产生的空间电荷层不仅有效地提高光生电子率,而且提高了电子空穴对的转移、分离,有效地延长了光生电子空穴对的寿命。同时,超薄MoS2纳米片和GO纳米片是高迁移率的电子转移媒介,进一步促进产生的光生电子空穴对在g-C3N4/Mo S2和g-C3N4/GO界面的转移、分离。实验表明合成的三元样品g-C3N4/Mo S2/GO的瞬态光电流强度是纯的g-C3N4样品的1.8倍,其降解Rh B溶液的光催化效率是纯的g-C3N4样品的2.3倍,结果证明了制备的三元复合纳米材料g-C3N4/MoS2/GO在可见光下较其它相关对比材料展现了更加优越的光电化学性能和光催化性能。(2)利用AgNO3的多功能修饰性在三聚氰胺热缩聚过程中复合MoS2纳米片一步合成一种由g-C3N4、Ag和MoS2纳米片组成的多孔三元复合纳米材料g-C3N4/Mo S2/Ag。AgNO3热解产生的气泡作为一种额外的软模板使三聚氰胺热缩聚过程自组装生成超薄g-C3N4纳米片和多孔结构,提高了对光的吸收性能。金属Ag和g-C3N4纳米片之间自组装耦合产生的纳米级Mott-Schottky效应不仅为电荷的转移、分离提供了有效通道,而且调整了g-C3N4纳米片的能带。同时,g-C3N4纳米片经调整后的能带结构有协同作用,加快了光生电子空穴对在二维g-C3N4/Mo S2异质结界面的转移和分离。通过该方法合成的三元复合纳米材料g-C3N4/Mo S2/Ag在可见光的照射下较其它相关对比材料,其瞬态光电流强度是纯的g-C3N4样品的大约3倍,其降解Rh B溶液的光催化效率是纯的g-C3N4样品的3.8倍,显著提高了光电化学性能和光催化性能。
[Abstract]:With the worsening of the global environment, people pay more and more attention to the problem of environmental pollution, using photocatalyst to convert solar energy into energy that can be directly used by human beings. It is an important direction in the research of renewable clean energy to solve the depletion of the earth's resources and the deterioration of the living environment. Graphite phase carbon nitride (GN) g-C3N4) is used as a new type of pollution-free environment-friendly optoelectronic material. In this paper, the nanocomposites of g-C _ 3N _ 4 have been synthesized by means of sonochemical method and thermocondensation method, respectively, and g-C _ 3N _ 4 / MoS _ 2 / go and g-C _ 3N _ 4 / MoS _ 2 / Ag have been synthesized. The structure, morphology and optical properties of the samples were characterized. The photochemical properties of the samples were characterized by transient photocurrent response test and AC impedance test. The photocatalytic properties of the samples were characterized by photocatalytic degradation of RhB solution. Based on the characterization and measurement results, the photogenerated electron hole transfer of the synthesized ternary composites was carried out. Separation and photocatalytic mechanism analysis. The research results of g-C _ 3N _ 4 nanocomposites provide references for the design and mass production of semiconductor catalytic materials with interfacial heterostructures and in-situ coupling cocatalysts. The main results are as follows. The g-C _ 3N _ 4 / MoS _ 2 / go was prepared by a simple sonochemical method. The ultrathin MoS2 and go nanocrystals in the ternary composite nanomaterials have greatly improved the absorption properties of visible light. Further more, the photogenerated electrons. MoS2 nanocrystals were coupled with go and graphite to form two kinds of P-N heterojunctions at the interfaces of g-C _ 3N _ 4 / Mo _ 2 and g-C _ 3N _ 4 / go. The space charge layer produced by these heterojunctions not only effectively increases the photoelectron yield, but also increases the transfer and separation of electron hole pairs, effectively prolongs the lifetime of photogenerated electron hole pairs. Ultrathin MoS2 and go nanocrystals are high mobility electron transfer mediums, which further promote the transfer of photogenerated electron holes to g-C _ 3N _ 4 / Mo _ 2 and g-C _ 3N _ 4 / go interfaces. The experimental results show that the transient photocurrent intensity of the synthesized ternary sample g-C3N4 / MoS2 / go is 1.8 times that of the pure g-C3N4 sample, and the photocatalytic efficiency of degradation of RhB solution is 2.3 times of that of the pure g-C3N4 sample. The results show that g-C _ 3N _ 4 / MoS _ 2 / go has better photochemical properties and photocatalytic properties than other related contrast materials in visible light.) the multifunctional modification of AgNO3 is used in melamine thermal condensation. One-step synthesis of a porous ternary composite nano-material, g-C _ 3N _ 4 / Mo _ 2 / Ag. Agno _ 3, composed of g-C _ 3N _ 4 / Mo _ 2 / Ag. Agno _ 3, as an additional soft template for self-assembly of melamine during thermal condensation of melamine. Thin g-C _ 3N _ 4 nanocrystals and porous structures, The nanoscale Mott-Schottky effect produced by self-assembly coupling between Ag and g-C _ 3N _ 4 nanoparticles not only provides an effective channel for charge transfer, but also for separation. Moreover, the energy band of g-C _ 3N _ 4 nanochip was adjusted, and the energy band structure of g-C _ 3N _ 4 nanochip had synergistic effect. The transfer and separation of photogenerated electron holes at the interface of two-dimensional g-C _ 3N _ 4 / Mo _ S _ 2 heterojunction were accelerated. The ternary composite nanomaterials, g-C _ 3N _ 4 / Mo _ S _ 2 / Ag, synthesized by this method, were compared with other related contrast materials under visible light irradiation. The transient photocurrent intensity is about 3 times of that of the pure g-C _ 3N _ 4 sample, and the photocatalytic efficiency of the Rh _ B solution is 3.8 times that of the pure g-C _ 3N _ 4 sample. The photochemical and photocatalytic properties of the sample are greatly improved.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ127.11;TB33

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