碳量子点嫁接介孔羟基磷灰石复合结构的设计及其调控光能转化的研究

Designing microstructure is an effective way to reduce the loss of light energy and improve its adsorption. On the other hand, a good composite interface could promote fast conversion of photoinduced electrons. In this project, a novel type of heterostructure is proposed to incorporate carbon quantum dots, which are modified by other elements, into the mesoporous hydroxyapatite frameworks. The objectives of the proposed research are to improve the absorption and conversion of light energy by designing the microstructure of the composites, and recognize the effects of the chemical composition at the interface between hydroxyapatite and carbon quantum dots on the behaviors of photoinduced electrons. First, the mesoporous hydroxyapatite, possessing different pore size and volume as well as morphology, will be prepared. Carbon quantum dots will be incorporated into the mesoporous hydroxyapatite frameworks by the reaction of surface groups or via non-covalent bonding. Then, the underlying effects of the interface between mesoporous hydroxyapatite and carbon quantum dots on the light energy conversion will be clarified by studying the fluorescence and photocatalytic activities of the composites. On the basis of experimental results and theoretic analysis, the generation, transfer, and recombination behaviors of photoinduced electrons in different mesoporous frameworks will be investigated so as to ascertain the light energy conversion mechanisms. Finally, the microstructure of the composites with excellent light adsorption and conversion will be achieved. The project will improve fundamental understanding of the relationships between inner behaviors and external performance, and is expected to create a low-cost and green nanomaterial with excellent fluorescence or photocatalytic activities that would have important applications in biological and environmental fields.

构建/优化复合微观结构，一方面可降低光损耗，提高光的吸收；另一方面，良好的复合界面可促进光生电荷的转化，从而实现光能的高效利用。本项目将不同异相元素表面功能化的碳量子点嫁接在介孔羟基磷灰石上，是通过微观结构设计调控光能吸收及转化的探索。该研究还涉及低成本、绿色羟基磷灰石与碳量子点二者嫁接界面处的化学组分调节光生电荷行为的机制。首先对介孔羟基磷灰石的孔径、孔容和形貌进行设计，然后再通过非共价键、表面基团间反应，让碳量子点嫁接到羟基磷灰石介孔壁上。通过表征所得结构光物理和光化学性能，阐明介孔羟基磷灰石与碳量子点间的相互作用对光吸收及转化的影响机制；结合实验结果与理论分析，揭示不同介孔结构中碳量子点的空间分布以及光生电荷的产生、复合、消耗和传输等行为。最后明确出有利于光吸收及转化的最优复合结构，为生物检测、环境处理应用领域提供一种低成本、绿色的新材料。

构建二元或多元复合体系是增强可见光吸收和提升光子转化效率的重要途径，充分理解调控复合结构光吸收与转化性能的关键因素是开发高效光能转化材料的基础。本项目制备不同异相元素表面功能化的碳量子点嫁接介孔羟基磷灰石的复合结构，拟通过组成和结构的设计对光吸收与转化进行有效调控。首先，研究表/界面相互作用在调控碳量子点嫁接介孔羟基磷灰石复合结构性能方面的关键作用，提出提高光吸收与转化效率的新思路。然后，分析微观结构对复合结构中光生电荷行为的影响，发展调控光吸收与转化的新策略。最后，优化组成和结构以及制备工艺，构建出有利于光吸收与转化的含碳量子点复合结构。取得的重要结果：1）发现了碳量子点与异质组元间的相互作用与复合结构的光生电荷行为具有很强的关联性，提出了通过调控界面反应来构筑光生电荷的传输和转移通道以增强光子转化效率的观点；2）给出了在碳量子点表面构建合适的限域微环境来调控光生电荷行为的新策略；3）原位构建出了羟基磷灰石/碳量子点/磷酸银光催化材料，实现了光生电子-空穴的有效分离，大幅提高了复合结构的光催化活性和稳定性；4）发展了碳量子点与异质组元的复合技术，获得了具有良好界面结构的含碳量子点复合体系，实现了光子转化效率的大幅提升。相关研究结果为基于组成和微观结构设计来发展高效的光吸收与转化材料提供了有益参考。