氮氟掺杂石墨烯量子点的控制合成及其光致发光调控研究

Graphene quantum dots (GQDs) due to the characteristics of small size effect and surface effect, make it have special optical properties. Doping can adjust the structure of the GQDs and thus change its optical properties. This project intends to research the content of and type of the nitrogen or fluorine doping to tune the band gap and the intensity of photoluminescence (PL)of the GQDs with nitrogen or fluorine doping. Mainly including the following several aspects: (1) by controlling the reaction conditions for the nitrogen or fluorine doping of GQDs; (2)To discuss the dependencies between the content and type of nitrogen or fluorine doping of GQDs and the band gap and the intensity of PL of GQDs, and thus realize the control of GQDs; (3)GQDs by co-doping of nitrogen and fluorine are obtained by the fluorination of the GQDs with nitrogen doping,and investigate its band gap and the intensity of PL, and compare the band gap of and the intensity of PL of GQDs with nitrogen or fluorine doping, find out the effective method to adjust its band gap and the intensity of PL;(4)To make the theory simulation, calculate and analyze the band structure, and strive to get the reasonable explanation. In short, the project is expected to the control of the content and type of nitrogen or fluorine doping and understand the dependencies between these factors and band gap and the intensity of PL of GQDs, and the control of the band gap and the intensity of PL in experiment and theory study aspect is a breakthrough, and provide experimental and theoretical basis for its application.

石墨烯量子点（GQDs）由于表面效应和小尺寸效应等特点，使其拥有特殊的光学性质。掺杂可以调节GQDs的结构，从而改变其光学性能。本项目拟研究氮、氟掺杂量和掺杂形式对氮氟掺杂的GQDs的带隙和光致发光（PL）强度的调控。主要包括以下几个方面：（1）通过控制反应条件对GQDs的进行氮、氟掺杂；（2）探讨氮、氟掺杂量和掺杂形式对GQDs带隙和PL强度的影响，进而实现对其调控；（3）通过对掺杂氮的GQDs进行氟掺杂，得到氮氟共掺杂的GQDs，研究其带隙和PL强度，并与氮、氟掺杂的GQDs的带隙和PL强度进行比较，找出调节其带隙和PL强度的有效方法；（4）进行理论模拟，计算并分析其能带结构，力求得到合理解释。总之，本项目期望通过对氮、氟掺杂量及其掺杂形式的控制来了解这些因素与其带隙和PL强度的关系，并希望对其带隙和PL强度调控的研究在实验与理论方面有所突破，为其应用提供实验和理论依据。

石墨烯量子点作为石墨烯的衍生物，除了具备石墨烯优异的性质外，还具有更强的量子限制效应和边缘效应，在催化、光电器件等方面有较好的应用前景。石墨烯量子点的光致发光效应作为其最为突出光学性能之一，不仅受到量子限制效应的影响，还受到表面/内部的功能性基团所影响。本项目主要研究氮、氟、硫、氮硫共掺杂石墨烯量子点的光致发光、光电催化性能。主要研究内容如下：（1）通过气相加热石墨烯量子点和二氟化氙混合物制备了氟/碳原子比高达84.25%和直径分布在2-6纳米的氟化石墨烯量子点，并系统研究了石墨烯量子点和氟化石墨烯量子点的光致发光特性。与石墨烯量子点相比，氟化石墨烯量子点的光致发光发射谱位置发生了明显的蓝移，蓝移了90纳米。（2）通过水热法合成了硫掺杂石墨烯量子点/二氧化钛纳米复合物。与石墨烯量子点/二氧化钛和二氧化钛相比，硫掺杂石墨烯量子点/二氧化钛纳米复合物具有明显增强光催化活性，在8分钟可降解甲基橙70%。（3）通过水热法以氨水作氮源，升华硫粉末作硫源，一步制备出了晶粒尺寸集中于2.5纳米，具有激发波长不依赖性的氮硫共掺石墨烯量子点。与石墨烯量子点相比，氮硫共掺石墨烯量子点的光致发光发射峰发生了54纳米的蓝移。（4）通过两步水热法合成了高产量的尺寸为2-6纳米的氮掺杂石墨烯量子点。结果表明，氮掺杂石墨烯量子点和还原氧化石墨烯复合材料展示良好的电催化活性，而且发现吡啶氮在氧还原反应中起了主要作用，平均电子转移数和初始电压都正比于吡啶氮的含量。总之，对石墨烯量子点进行改性掺杂进而对光致发光、光电催化性能调控为进一步加深其在光电催化应用有重要的科学意义。