量子点敏化半导体/石墨烯复合纳米材料的光催化特性及机理

The design and preparation of semiconductor photocatalysts is one of the key issue for the photocatalytic water splitting for hydrogen evolution. In this project, we propose firstly to prepare nanocomposites such as carbon quantum dots (CQDs)/TiO2/reduced graphene oxide/metallic nanoparticles and CQDs/CdS/reduced graphene oxide/metallic nanoparticles. Their visible-light driven water splitting for photocatalytic hydrogen production, the photoelectrochemical properties and mechanism will be investigated. We will prepare size-controlled CODs by electrochemical methods and to synthesize CQDs/TiO2/reduced graphene oxide nanocomposites by sol-gel or hydrothermal approaches. The photocatalytic activity of hydrogen evolution will be detected using a gas chromatograph for the powder nanocomposite. Besides, thin film electrodes of the nanocomposites will be assembled with controllable nanostructure by dip-coating technique. The photocatalytic and photoelectrochemical conversion and charge transfer mechanism for the composites film electrodes will be declared in combining with electrode surface analysis. The doping of nitrogen into TiO2 and the upconversion luminescence properties of CQDs will promise to harness the use of the full spectrum of sunlight. The presence of reduced graphene oxide can dramatically improve photoinduced charge transfer performance and inhibit the charge recombination. The metallic nanoparticles can enhance surface chemical reaction rate. Thus, the efficiency of the photocatalytic hydrogen production can be improved for such nanocomposites. This study will provide novel information to understand the mechanism and new photocatalysts with high efficiency in the application of visible-light-driven water splitting for hydrogen evolution and other areas.

太阳能光催化分解水制氢的一个关键问题是半导体光催化材料的设计与制备。本项目在前期研究碳、氮掺杂纳米TiO2的基础上，提出制备碳量子点修饰半导体TiO2（CdS）/石墨烯（金属纳米粒子）复合新材料并研究其光催化制氢与光电化学特性和反应机理。通过电化学方法制备尺寸可控的碳量子点，利用溶胶-凝胶、水热法制备碳量子点/TiO2(CdS) /石墨烯(金属纳米粒子)复合材料并测试粉体材料光催化产氢活性。通过浸渍-提拉与组装方法制备结构可控的复合纳米结构薄膜电极，结合表面分析研究碳量子点/TiO2（CdS）/石墨烯复合薄膜电极的光电转换及电荷传输机理和能级关系。利用N元素掺杂、碳量子点的光转换特性实现光的广谱吸收；而石墨烯能大幅度提高光生电荷的传输能力，抑制光生电荷复合，利用金属纳米粒子的修饰提高表面反应速率，达到提高光催化制氢效率的目的。研究新型功能复合材料在可见光光电催化制氢等方面的应用。

氢能清洁无污染，太阳能光解水制氢是具有重大意义的研究课题，其中关键的问题是半导体光催化剂的设计与制备，较高的光吸收特性、快速的光生载流子分离以及界面反应是提高光催化活性的关键。.本项目围绕量子点敏化以及元素掺杂提高TiO2对光的吸收，引入石墨烯提高载流子的分离等方面开展了系列研究工作。通过阳极氧化的方法制备TiO2纳米管，研究了碳（硅，CdS）量子点敏化的TiO2以及C掺杂的TiO2电极的光分解水特性，其中碳量子点敏化的TiO2的研究论文被国内外学者图文亮点引用。.利用水热方法制备了TiO2与石墨烯的复合材料并研究了其光解水制氢特性，当RGO含量为0.2 wt%复合材料可以达到43.8μmol h-1的产氢效率，是P25的1.6倍。 研究了水热方法制备碳点-P25以及新的TiNxOy材料的光催化特性等。.发展了一种制备氧化物半导体的全新的实验方法-火焰辅助热解方法，该方法无能耗无废液排放，可用于制备金属元素（Fe， Mn）修饰的TiO2、Ti3+自掺杂的TiO2和TiO2-SiO2的复合材料，还利用火焰辅助热解方法制备了Ta2O5，Nb2O5等氧化物并探索验证了其在光催化制氢、染料敏化太阳能电池以及锂电储能等方面的应用。.依托该项目发表SCI研究论文16篇，其中国际学术期刊发表13篇，被引用100余次，申请国家发明专利5项，获授权2项，培养博士、硕士研究生8人。