Mhlanga Nikiwe, Ntho Thabang A, Chauke Hleko, Sikhwivhilu Lucky
DSI/Mintek Nanotechnology Innovation Centre, Randburg, South Africa.
Advanced Materials Division, Mintek, Randburg, South Africa.
Front Chem. 2022 Mar 9;10:832282. doi: 10.3389/fchem.2022.832282. eCollection 2022.
Surface-enhanced Raman spectroscopy (SERS), a marvel that uses surfaces to enhance conventional Raman signals, is proposed for a myriad of applications, such as diagnosis of diseases, pollutants, and many more. The substrates determine the SERS enhancement, and plasmonic metallic nanoparticles such as Au, Ag, and Cu have dominated the field. However, the last decades have failed to translate SERS prototypes into real-life applications. Irreproducibility on the SERS signal that stems from the roughened SERS substrates is the main causative factor for this observation. To mitigate irreproducibility several two-dimensional (2-D) substrates have been sought for use as possible alternatives. Application of 2-D graphene substrates in Raman renders graphene-enhanced Raman spectroscopy (GERS). This account used density functional theory (DFT) substantiated with experimental Raman to compare the enhancement capabilities of plasmonic Au nanoparticles (SERS), graphene substrate (GERS), and coupling of the two SERS and GERS substrates. The DFT also enabled the study of the SERS and GERS systems molecular orbital to gain insight into their mechanisms. The amalgamation of the SERS and GERS occurrence, i.e., graphene doped with plasmonic metallic substrates showed a pronounced enhancement and matched the Au-driven enhancement emanating from both electromagnetic and charge transfer SERS and GERS mechanisms.
表面增强拉曼光谱（SERS）是一种利用表面增强传统拉曼信号的神奇技术，被广泛应用于多种领域，如疾病诊断、污染物检测等。基底决定了SERS的增强效果，金、银、铜等等离子体金属纳米颗粒在该领域占据主导地位。然而，在过去几十年中，SERS原型未能转化为实际应用。源于粗糙SERS基底的SERS信号不可重复性是导致这一现象的主要原因。为了减轻不可重复性，人们一直在寻找几种二维（2-D）基底作为可能的替代方案。二维石墨烯基底在拉曼光谱中的应用产生了石墨烯增强拉曼光谱（GERS）。本文利用密度泛函理论（DFT）并结合实验拉曼光谱，比较了等离子体金纳米颗粒（SERS）、石墨烯基底（GERS）以及两种基底耦合的SERS和GERS的增强能力。DFT还使得对SERS和GERS系统分子轨道的研究成为可能，从而深入了解它们的机制。SERS和GERS的结合，即掺杂有等离子体金属基底的石墨烯，显示出显著的增强效果，并且与由电磁和电荷转移SERS及GERS机制产生的金驱动增强效果相匹配。
