新型石墨烯/贵金属/金属氧化物复合纳米材料的可控合成及光催化性能研究

Graphene based inorganic composite nanomaterials are one of the great research area in nanomaterials. In this project, a novel ternary composites nanocatalyst of graphene/ noble metal/metal oxides will be fabricated. This new designed composite nanomaterials will take advantage of all the good properties of the three components: large surface and novel photoelectric properties of graphene, the strong photocatalytic properties of metal oxides as well as the perfect electron transfer properties of the noble metals nanoparticles. The controllable loading factors of noble metals and metal oxides onto the graphene matrix will be deeply studied. We will study the effect of the reaction conditions on the morphology, size, chemical composite and structure of the composite nanomatierials. Various spectroscopy, surface analysis technologies will be used to study the photoelectric properties of the composite nanomaterials (such as photoelectric efficiency, optical absorption edge, band width as well as electron transfer properties) to reveal the relationship of the nanomaterial structure to the photoelectric properties of the composite materials. Then the nanocomposite materials will be applied on the photocatalytic degradation of organic pollutants in water. The mass collection, transfer, degradation reaction at the surface of the composite materials will be deeply studied to reveal the surface process and degradation mechanism of the organic pollutants. Then the relationship of performance of photocatalyst with the structure of the composite nanomatierials will be clarified. The carry out of this project will offer a system understand for the design and application of novel high efficient photocatalyst in degradation of organic pollutants in water.

基于石墨烯的无机纳米复合材料研究是当前纳米材料科学领域的研究热点之一。本课题将石墨烯大比表面积和独特的光电性能、金属氧化物的强光催化性能和贵金属纳米粒子优异的电子传输特性三者有机结合, 设计了一种新型的基于石墨烯/贵金属/金属氧化物三元复合纳米催化材料。采用氧化石墨烯作载体，以金属盐为前驱体，开展贵金属和金属氧化物负载的石墨烯复合材料的可控制备研究，揭示反应条件对三元复合材料形貌和尺寸、化学组成、结构与性能的影响规律；通过采用各种谱学和表面分析技术研究复合材料的光电流效率、光吸收边带、禁带宽度、电荷传输特性等光电性能，明确复合材料结构与光电性能之间的关系；研究水中有机污染物在复合材料上的富集、迁移、催化降解反应等界面过程和机制，阐明复合材料结构与光催化性能之间的构效关系。课题的实施为新型高效光催化剂的开发研究提供系统的理论依据。

本课题研究以石墨烯基复合纳米材料的构建及其光电性能研究为主要研究对象，以污染物去除，储能产氢为主要应用目标，展开系列研究。由于石墨烯具有超高电子迁移速率、较长的电子平均自由路径、良好的热传导和较高的机械强度与韧性，适合于做为基底材料来负荷可见光敏化窄禁带半导体来构建负荷纳米光催化剂。由于石墨烯的界面效应，半导体纳米材料能稳定的附着在石墨烯表面，并具有较高的分散度与良好的稳定性。二者相结合，不仅保持了各自的优势性能，还赋予了复合体优异的协同效应，在污染物光催化处理、储能、产氢等方面都展现出较好的性能。如制备的graphene-Bi2MoO6/Bi3.64Mo0.36O6.55，TiO2/graphene/Cu2O三元光催化剂不仅能灵敏的响应可见光，得益于石墨烯快速的电子传输特性，从而有效的抑制了光生载流子的复合几率。本研究中还合成了三维石墨烯-MnS，石墨烯/赤铁矿复合材料，前者展现出良好的储能特性，后者则具有优异的吸波性能，这些都得益于石墨烯的引入。此外还开发了g-C3N4/graphene dots，C/X（X=N，F，Cl）TiO2@C3N4 复合非金属半导体光催化剂应用于光解水产氢研究。该材料具有极好的可见光响应特性，在光解水产氢与光催化降解有机污染物方面均展现出较高的效率。 .针对以TiO2为催化剂的光催化氧化反应存在禁带宽度大，仅能被紫外光激发才能产生光生载流子，催化剂自身会充当短路微电极，增大光生空穴-电子对的复合几率，单一TiO2相催化效率低的问题。因我们构建了不同形貌，不同结构的TiO2光催化剂如TiO2 sphere, TiO2-Bi2MoO6/Bi3.64Mo0.36O6.55, Ag-AgI-WO3-TiO2，并深入探讨其作用机制。研究发现，构建Z型阶梯式能带结构是提高TiO2基催化剂的关键因素，同时，引入贵金属纳米颗粒，则能进一步提高其催化活性。