石墨烯-氮化硼双层异质结构的生长及其表面增强拉曼特性的研究

Food safety problem, especially in China, has become more and more severe in these years, the need for simple and smart food detection becomes urgently necessary. Surface-enhanced Raman spectroscopy (SERS) is a highly-sensitive tool for molecule identification and has attracted much interest. Designing and developing substrates which can significantly enhance the intensity of Raman signal of molecule(s) is the key goal. Graphene is an ultrathin, flexible, fidelity and green enhanced Raman substrate, and the only disadvantage is its modest Raman enhancement factor. Combining chemical enhancement and electromagnetic enhancement is a promising method for solving this problem. However, the Raman enhancement factor has not been improved in graphene-metal hybrid structure. In this proposal, we introduced the BN layer and design a flexible and ultrathin layer stacked by grahene and BN layers (namely, grahene-BN hybrid structure) for novel SERS-substrate applications. As a result of the out-of-plane broken symmetry (which can be controlled by surface doping), the designed grahene-BN hybrid structures could have exceptionally large surface dipole. This surface dipole can not only improve the chemical Raman enhancement; but also eliminate the energy dissipation channel directly from metal to graphene, allow manipulating the LSPR of the surface metal nanoparticle array, which could result in a much larger electromagnetic enhancement. This grahene-BN hybrid structure could be very helpful for smart, non-destructive, highly sensitive identification of molecules.

当下，食品安全问题层出不穷，对简便快速的检测手段的需求日益迫切。表面增强拉曼光谱（SERS）作为一种新型分子探测手段引发了极大的关注。设计研发对拉曼信号有显著增强作用的衬底是该领域发展的关键。石墨烯作为一种超薄、柔性、保真、绿色的化学增强拉曼衬底，唯一不足是拉曼增强因子较小，将化学增强和电磁增强结合有望解决此瓶颈。然而，石墨烯与金属的直接复合体系并未展现出拉曼增强因子的进一步提高。本申请设计引入氮化硼夹层，构造石墨烯-氮化硼双层异质结构，作为金属的柔性介质层。一方面，由于具有内在的、可被掺杂显著增强的面外对称性破缺，石墨烯-氮化硼双层结构可形成较大的表面偶极，有望获得更高的化学增强能力；另一方面，通过隔断金属到石墨烯的能量弛豫和耗散通道、形成衬底表面偶极与金属LSPR的耦合，有望实现对金属LSPR的调控，提高其电磁增强因子，从而获得快速、无损、高灵敏度的分子识别与检测能力。

为了应对食品安全问题，需要简便、快速而有效的检测识别食品中的有毒或污染物。表面增强拉曼是一种新型的分子探测手段，其技术的关键在于设计开发对拉曼信号有增强能力的衬底。对于拉曼信号的增强机制有两种：化学增强和电场增强，将这两种机制有效结合有望获得更优的增强效果。石墨烯、氮化硼等二维材料作为近年来的研究热点，不仅具有优异的电学、光学和力学特性，而且展现出对拉曼信号的化学增强能力。将二维材料与金属相结合有望实现化学增强和电场增强的有效结合。本申请提出以二维材料作为金属纳米阵列的柔性介质层，在引入化学增强的同时，隔断金属LSPR的能量弛豫和耗散通道的同时，有望实现对金属LSPR调控，进一步提高电磁增强因子，实现对分子的快速、无损、高灵敏度的识别与检测能力。本申请围绕高性能表面增强拉曼衬底的设计、制备和研发开展工作，主要进展和成果包括：以氮化硼作为金纳米阵列的柔性介质层，实现了具有优异的热稳定性、高灵敏度、且可重复使用的表面增强拉曼衬底；发展了对有毒或有害物质的原位检测与降解技术，推进了表面增强拉曼的应用。这些研究成果丰富了表面增强拉曼衬底的制备方法；为进一步提高其性能指标提供了新思路；同时对基于异质结构的其他应用研究也具有一定的参考价值。