碳纳米材料因其结构可调性和多维特性成为跨学科领域的研究热点。碳点（CDs）作为碳纳米材料的典型代表，具有优异光学性质、良好生物相容性和易于表面功能化的优势，在离子/分子检测、细胞成像以及防伪和信息加密等传感领域展现出广阔的应用前景。然而，CDs实际应用中仍面临一些挑战，如：量子产率较低、易团聚、发光集中在蓝绿色区域以及室温磷光较难实现等问题，这些限制了CDs在传感领域的发展。针对这些问题，本文通过氮元素掺杂、表面功能化以及与水滑石（LDHs）复合的策略来提升CDs的性能，深入探究CDs及其LDHs复合材料的形貌、结构、元素组成以及发光性能，并探索其在传感领域的应用潜力。

本文主要的研究内容和结果如下：

（1）通过水热/溶剂热法，以聚乙二醇、色氨酸和洗煤废水为前驱体，实现了对CDs的氮掺杂以及表面功能化，制备出表面具有丰富官能团的氮掺杂碳点（BCDs）。BCDs通过“on-off-on”的过程可以实现对Hg²⁺和谷胱甘肽（GSH）的选择性检测，在0.01-100 µM和0.01-60 µM的线性范围内分别响应Hg²⁺和GSH，检测限分别为6.27 nM和3.53 nM。基于BCDs可逆的传感机制，开发了可用于Hg²⁺和GSH快速、可视化检测的纸基和水凝胶基固态传感器，并且也成功将BCDs用于人骨肉瘤细胞（MG-63）的成像与检测。此外，还将BCDs配制成荧光墨水，探究其在防伪和信息加密领域的应用。

（2）通过静电自组装的方式，将邻苯二胺和邻苯二甲酸为前驱体制备的氮掺杂碳点（YCDs）分别掺入Mg₂Al-LDHs和Zn₂Al-LDHs层间，成功制备了两种室温磷光材料（YCDs/Mg₂Al-LDHs和YCDs/Zn₂Al-LDHs）。研究发现，YCDs本身无磷光，但在插入LDHs层间后，LDHs的刚性二维纳米空间有效抑制了YCDs的振动和转动，促进系间窜越生成三重态，从而实现室温磷光发射。YCDs/Mg₂Al-LDHs-20和YCDs/Zn₂Al-LDHs-20在紫外灯照射下肉眼可见余辉时间最长分别可达9 s和11 s。此外，通过与聚乙烯醇（PVA）复合，进一步拓展了复合材料在防伪和信息加密领域的应用。

Carbon nanomaterials have become a popular research topic in interdisciplinary fields due to their structural tunability and multidimensional properties. Carbon dots (CDs), as a typical representative of zero-dimensional carbon nanomaterials, have the advantages of excellent optical properties, good biocompatibility, and easy surface functionalization, and exhibit broad application prospects in sensing fields such as ion/molecule detection, cellular imaging, and anti-counterfeiting and information encryption. However, there are still some challenges in the practical application of CDs, such as low quantum yield, easy agglomeration, luminescence concentrated in the blue-green region, and room-temperature phosphorescence is more difficult to realize, which limit the development of CDs in the field of sensing. To address these issues, this paper enhances the performance of CDs through the strategies of nitrogen doping, surface functionalization, and compositing with hydrotalcites (LDHs) to deeply investigate the morphology, structure, elemental composition, and luminescent properties of CDs and their LDHs composites, and to explore the potential of their application in the field of sensing.

The main research and results of this paper are as follows:

(1) Through hydrothermal/solvothermal methods, nitrogen doping and surface functionalization of CDs were achieved using polyethylene glycol, tryptophan, and coal washing wastewater as precursors, preparing nitrogen-doped carbon dots (BCDs) with abundant surface functional groups. BCDs enable selective detection of Hg²⁺ and GSH through an “on-off-on” process. They exhibit linear responses to Hg²⁺ (0.01-100 µM) and GSH (0.01-60 µM), with detection limits of 6.27 nM (Hg²⁺) and 3.53 nM (GSH). Based on the reversible sensing mechanism of BCDs, paper-based and hydrogel-based solid-state sensors were developed for the rapid and visual detection of Hg²⁺ and GSH. Furthermore, BCDs were successfully applied for imaging and detection in human osteosarcoma cells (MG-63). Additionally, BCDs were formulated into fluorescent ink, and their applications in anti-counterfeiting and information encryption were investigated.

(2) Through electrostatic self-assembly, nitrogen-doped carbon dots (YCDs) prepared with o-phenylenediamine and o-phenylenedicarboxylic acid as precursors were doped into the interlayers of Mg₂Al-LDHs and Zn₂Al-LDHs, respectively, and two room-temperature phosphorescent materials (YCDs/Mg₂Al-LDHs and YCDs/Zn₂Al-LDHs) were successfully prepared. Studies have found that YCDs themselves are non-phosphorescent, but after insertion into the layers of LDHs, the rigid two-dimensional nano space inhibition of LDHs effectively suppresses the vibration and rotation of YCDs and promotes intersystem scampering to generate a triplet state, thus realizing room-temperature phosphorescence emission. YCDs/Mg₂Al-LDHs-20 and YCDs/Zn₂Al-LDHs-20 have the longest naked-eye visible afterglow times of up to 9 s and 11 s, respectively, under UV light irradiation. Additionally, by incorporating with polyvinyl alcohol (PVA), the applications of the composite materials in anti-counterfeiting and information encryption have been further expanded.