石墨烯量子点/WO3超薄纳米片异质结的制备及光催化性能研究

Both enhancing the absorption of visible light and increasing separation efficiency of light-generated charge (electron and hole) are the effective way to improve the photocatalytic properties of semiconductor. Two-dimensional(2D) ultra-thin nanomaterials with super great surface area display high anisotropy、the quantum confinement effect and a very short carrier diffusion paths. Building graphene quantum dots(GQDs) heterojunctions, can enhance the visible light absorption and improve the light-generated electron - hole separation efficiency. The advantage of two aspects was combined in this project. We will design graphene quantum dots/2D ultra-thin WO3 nanosheets heterojunctions photocatalyst, and study the synthesis of GQDs、2D ultra-thin WO3 nanosheets and heterojunctions. The coupling mechanism of GQDs/2D ultra-thin WO3 nanosheets will be studied for propose the theories and methods of designing GQDs/2D ultra-thin nanosheets composites with high photocatalytical activity. In addition, it is investigated that the dynamic behavior of the surface photo-generated charge separation and recombination and transferring, so as to deeply reveal the influence of quantum confinement effect and built-in electric field of heterojunctions on photocatalytic properties. We will elucidate the photocatalytical mechanism of 2D ultra-thin conductor heterojunctions which will become an important basis for promoting two-dimensional ultra-thin semiconductor material applied in the field of sunlight catalyst

增强可见光的吸收与提高光致电荷（电子和空穴）的分离效率是提高半导体光催化性能的有效途径。二维(2D)半导体纳米材料，具有超高的比表面积，表现出高度的各向异性、量子限域效应和极短的光生载流子扩散路径。石墨烯量子点异质结的构建，能增强对可见光吸收，提高了光生电子-空穴的分离效率。本项目将结合二者的优点，构建石墨烯量子点（GQDs）/超薄WO3纳米片复合光催化剂，研究2D超薄WO3纳米片、石墨烯量子点（GQDs）的合成方法及二者的耦合机制，提出设计高催化活性的GQDs /2D超薄结构复合材料的理论和方法。探讨材料表面光生电荷分离与复合、传输等动力学行为，深入揭示量子限域效应、异质结内建电场对光催化性能的影响机制。本课题的开展，将阐明2D超薄半导体及其异质结的光催化作用机理，为促进二维半导体材料在太阳光催化领域的应用提供重要依据。

超薄2D和超细1D纳米结构能产生明显的量子限域效应和表面效应，同时具有极短的光生载流子扩散路径，这些优点均有利于提高半导体光致电荷的分离效率、增多光催化活性位点，从而提高光催化效率。本项目以WO3为主要研究对象，通过插层-剥离法成功获得超薄WO3•2H2O纳米片，本法可延伸至超薄SnS2纳米片的制备，证明采用此法剥离层状材料获得少层或单层的超薄结构是一种通用的方法；采用水热法制备超细WOx纳米线，研究超薄纳米片和超细纳米线的形成机理，并探索这些特殊结构对光催化活性的影响；以超细WOx纳米线为基础，分别采用溶剂热法制备石墨烯量子点/WO3纳米线异质结以及g-C3N4/WO3纳米线异质结；以超薄WO3•2H2O纳米片为基础，制备CdS量子点/WO3纳米片异质结，建立超薄WO3纳米片和超细WO3纳米线异质结光催化材料的制备理论和方法；研究WO3异质结复合材料中光生电荷分离与复合、传输等动力学行为，深入揭示量子限域效应、异质结形成与配比对光生电荷行为的影响机制。本项目的开展本项目开展这方面的研究具有将为构建具有可见光吸收、高催化活性光催化剂提供一条崭新的途径，也为解释1D、2D 材料及其异质结表面光催化反应机理提供重要的理论依据，具有重要的理论意义和学术价值。