The development of ultrasensitive and biocompatible Surface-Enhanced Raman Spectroscopy (SERS) substrates, able to provide uniform and reproducible signals, has become a focus of study in the last decade. Graphene, with his advantageous properties, such as photoluminescence quenching of fluorescent dyes, chemical inertness and biocompatibility, allows to overcome many important limitations of conventional metal SERS substrates. In this work, we develop ultrasensitive graphene substrates by ethanol Chemical Vapor Deposition (CVD). Large-area thin films composed of nanosized sp² grains surrounded by disordered regions are obtained by lowering the growth temperature from the standard 1070 °C to 700 °C. Our substrates are able to detect trace amounts of molecules, down to 6·10^-11 M, which is the lowest concentration that has been achieved in Graphene-Enhanced Raman Spectroscopy (GERS) with rhodamine 6G (R6G) as probe molecule. This outstanding result is attributable to two main features: i) more efficient charge transfer due to the energy level matching between R6G and the nanocrystalline graphene film; ii) large number of grain boundaries acting as “trapping sites” for the molecules.

开发能够提供均匀和可重复信号的超灵敏和生物相容性表面增强拉曼光谱 (SERS) 基板已成为过去十年的研究重点。石墨烯具有其优越的特性，例如荧光染料的光致发光猝灭、化学惰性和生物相容性，可以克服传统金属 SERS 基板的许多重要限制。在这项工作中，我们通过乙醇化学气相沉积 (CVD) 开发了超灵敏的石墨烯基板。通过将生长温度从标准的 1070°C 降低到 700°C，获得由无序区域包围的纳米 sp ²晶粒组成的大面积薄膜。我们的底物能够检测微量分子，低至 6·10 ^-11M，这是在石墨烯增强拉曼光谱 (GERS) 中以罗丹明 6G (R6G) 作为探针分子的最低浓度。这一突出的结果归因于两个主要特征：i）由于 R6G 和纳米晶石墨烯薄膜之间的能级匹配，更有效的电荷转移；ii) 大量晶界作为分子的“俘获点”。