Graphene quantum dot (GQD) represents an emerging noble metal-free surface-enhanced Raman scattering (SERS)-active nanomaterials for applications such as optoelectronics, chemical sensing, and biomedical imaging and therapy. However, it lacks a scalable method to synthesize GQD with selective structures and the fundamental understanding of their SERS enhancement through charge transfer between GQD and probe molecules. Here a bottom–up liquid-phase synthesis of colloidal GQDs with selective bandgaps using atmospheric-pressure microplasmas is reported. Electron microscopic and optical spectroscopic characterizations suggest that highly crystalline GQDs with nanographene structures can be synthesized with ambient conditions using microplasmas. Moreover, the bandgaps of GQDs are tuned from 2.8 to 3.18 eV by controlling the size of organosulfate micelles. Raman spectroscopic study demonstrates that the as-synthesized GQDs exhibit a unique quantum dot bandgap-dependent SERS enhancement property with an improved charge transfer between the GQD and probe molecules. This study provides an insight into the fundamental of semiconductor-enhanced Raman scattering of GQDs and scalable production of structure-controlled GQDs using plasma-activated chemistry.

中文翻译：

---

来自带隙控制石墨烯量子点的无贵金属表面增强拉曼散射增强

石墨烯量子点 (GQD) 是一种新兴的无贵金属表面增强拉曼散射 (SERS) 活性纳米材料，可用于光电子学、化学传感、生物医学成像和治疗等应用。然而，它缺乏一种可扩展的方法来合成具有选择性结构的 GQD 以及通过 GQD 和探针分子之间的电荷转移对其 SERS 增强的基本理解。本文报道了使用大气压微等离子体自下而上液相合成具有选择性带隙的胶体 GQD。电子显微镜和光学光谱表征表明，可以使用微等离子体在环境条件下合成具有纳米石墨烯结构的高结晶 GQD。此外，GQD 的带隙从 2.8 调整到 3。18 eV 通过控制有机硫酸盐胶束的大小。拉曼光谱研究表明，合成的 GQD 表现出独特的量子点带隙相关 SERS 增强特性，并改善了 GQD 和探针分子之间的电荷转移。这项研究提供了对 GQD 的半导体增强拉曼散射和使用等离子体激活化学可扩展生产结构控制 GQD 的基本原理的深入了解。