基于大共轭平面结构的石墨烯量子点与金属酞箐复合超薄膜气体传感器研究

Graphene thin film gas sensors generally suffer from dense structure due to compact stack of thin layer nanosheets, which hinder the viscosity and absorption of gas molecules and further seriously affect their gas sensing detection. Graphene quantum dots (GQDs) are a kind of novel carbon nanomaterials, which possesses characters of both graphene and quantum dots. In this project, a new material that has novel phthalocyanine (MPc)-like derivative containing plane-conjugated structures will be synthesized through designing at molecular level based on the similar nanometer sizes and conjugated structures of GQDs and MPc. The properties of GQD-MPc can be controlled by the sizes and different doped atoms of GQDs, and/or by changing the central metal and surrounding substituent groups of MPc. Subsequently, GQD-MPc ultra-thin film with oversized plane- conjugated structure will be fabricated through Langmuir-Blodgett method and electrostatic self-assembly technique. The intramolecular electron in the conjugated system can be transfer quickly by modifying the molecular orientation, crystallinity and microstructure of the GQD-MPc ultra-thin film. Finally, GQD-MPc ultra-thin film gas sensors will be constructed and their sensing behaviors will be measured. We will further focus on the study of the electron transfer, charge transportation, and the kinetics of their sensing performance, as well as their response mechanisms. This project will achieve ultra-sensitive detection with second-level fast response and recovery time at room temperature, and high sensitivity at ppt level. This work will establish the research basis and provide new idea for novel GQD thin film gas sensor.

石墨烯薄膜气体传感器通常由于薄片层堆砌而形成致密结构，易阻碍和粘滞气体分子，不利于气敏检测。石墨烯量子点（GQDs）是一种兼具石墨烯和量子点特性的新型碳纳米材料。基于GQDs与金属酞菁（MPc）分子的尺寸大小同在纳米级别，本项目首先通过调控GQDs的尺寸和掺杂原子以及MPc的中心金属和周边取代基，从分子角度设计并制备出含GQD共轭平面结构的类MPc衍生物（GQD-MPc）。接着采用Langmuir-Blodgett拉膜法和静电自组装技术制备超大共轭平面的GQD-MPc超薄膜，通过控制超薄膜的分子取向、结晶性和微观结构，促进分子内的电子在共轭体系中快速转移。最后构建GQD-MPc超薄膜气体传感器并测试气敏性能，揭示电子转移、电荷传输和响应动力学规律，阐明传感机理，实现在室温下对气体分子的高灵敏检测（ppt量级）以及快速响应和恢复（秒量级），为新型GQD薄膜气体传感器奠定研究基础和提供新思路。

由于石墨烯量子点（GQDs）尺寸大小与金属酞菁（MPc）分子直径同在纳米级别，这有利于从分子角度设计并制备含GQD共轭平面结构的类MPc衍生物。GQD-MPc可看作一个超大共轭平面分子结构体系。GQD-MPc保留了GR-MPc中GR优异的电荷传输特性，可以保证电子在大分子内的快速转移，从而实现传感器对气体分子的超灵敏响应。我们将GQDs与MPc结合，设计并制备出了高灵敏和快响应的GQD-MPc薄膜气体传感器，表现出优异的气敏特性。.以四羧基酞菁钴CoPc-COOH为代表的金属酞菁MPc，与石墨烯量子点GQDs结合，构建了一种新型的具有超大共轭平面的GQD-CoPc 薄膜气体传感器，实现了在室温下对氧化性气体二氧化氮（NO2）的检测极限为50 ppt，响应时间为50 s，在激光辅助照射下恢复时间为50 s。对还原性气体氨气（NH3）的检测极限为100 ppt，响应时间为60 s，在红外灯加热辅助下恢复时间为35 s。揭示了GQD-MPc 薄膜结构与薄膜气敏性能的内在联系，构筑了GQD-MPc 薄膜结构，阐明了其气敏机理，本项目为新型GQD-MPC 薄膜气体传感器奠定了研究基础和提供新思路，对实现其商业化应用具有重要的研究意义。