纤维素水热炭化：纳米碳点的生成和荧光性能调控机理

Fluorescent carbon quantum dots (CQDs) are a new class of carbon nanomaterials that have emerged recently and have garnered much interest as potential competitors to conventional semiconductor quantum dots. CQDs was composed by SP2 and unsaturated SP3 hybridization carbon atoms. Since their discovery, CQDs have become the most popular nanomaterials among the nanocarbon family，including fullerene，the carbon nanotube and graphene．In the present work, we will develop a simple, low cost, and green preparative strategy toward water-soluble CQDs by hydrothermal treatment of cellulose for the first time. The as-prepared CQDs will be characterized by UV–Vis, PL, XPS, FTIR and TEM, etc. Effect of experimental parameters which include reaction time, temperature and pressure on the morphology, particle size and distribution, crystalline structure, surface functional groups and fluorescent properties will be investigated systematically. Working mechanism of surface functional groups on the fluorescent properties of CQDs will be established. Intermediate products generated from cellulose hydrothermal carbonization will be measured in detail. Mechanism of formation and fluorescent properties adjustment of CQDs synthesized via cellulose hydrothermal carbonization will be established. The potential application of the obtained CQDS for high active composite photocatalyst, high sensitive and high selective detective probe will be investigated. The results will provide guided and support of both science and technology for the preparation of high performance CQDs from renewable biomass.

碳量子点是近几年来发现的一种以碳为骨架，由SP2 及不饱和SP3 杂化碳原子组成的新型荧光纳米粒子，是继富勒烯、碳纳米管及石墨烯之后最热门的碳纳米材料之一。本项目拟以自然界中储量最大的天然高分子纤维素为原料，采用环境友好的水热炭化法制备水溶性荧光纳米碳点，对反应条件改变引起的碳点微观形貌和光学性能改变进行系统研究。解析不同反应温度、时间、压强下碳点形貌、粒径分布、表面官能团结构与光学性能的改变规律，阐明表面功能基团对碳点荧光性能的影响机制，探讨纤维素水热条件下水解步骤，研究水热中间产物聚集成核机理及生长历程，阐明纤维素水热炭化纳米碳点的形成机理，建立并验证碳点的光学性能调控规律，确定纤维素水热炭化纳米碳点的结构调控制备体系，为进一步实现生物质资源制备高性能纳米碳点提供理论基础。

项目以纤维素及其衍生物、天然生物质多糖、合成有机小分子为原料，研究了反应温度、时间对碳点的粒径分布、晶相结构、化学性质与光学性能的改变规律，阐明了表面性能对表现出荧光等光学性能的影响机制，探讨了纤维素水热条件下水解机理，研究了水热中间产物聚集成核机理及生长历程，阐明了水热碳点的形成机理。确定了水热炭化纳米碳点的结构调控制备体系；通过非金属元素N、B、Si及金属元素Cu掺杂对其进行改性，构建不同表面能的功能性纳米碳点，研究了碳点在离子检测、有机小分子检测、细胞标记、光催化剂、LED发光以及室温磷光材料方面的应用性能，揭示了结构对其性能的影响规律。