The Research Institute of Advanced Technologies, Ningbo University, No. 818 Fenghua Road, Ningbo 315211, China.
School of Physical Science and Technology, Ningbo University, No. 818 Fenghua Road, Ningbo 315211, China.
Biosensors (Basel). 2022 Jan 19;12(2):50. doi: 10.3390/bios12020050.
Surface-enhanced Raman scattering (SERS) is a non-destructive spectra analysis technique. It has the virtues of high detectivity and sensitivity, and has been extensively studied for low-trace molecule detection. Presently, a non-noble-metal-based SERS substrate with excellent enhancement capabilities and environmental stability is available for performing advanced biomolecule detection. Herein, a type of molybdenum carbide/molybdenum oxide (MoC@MoO) heterostructure is constructed, and attractive SERS performance is achieved through the promotion of the charge transfer. Experimentally, MoC was first prepared by calcinating the ammonium molybdate tetrahydrate and gelatin mixture in an argon atmosphere. Then, the obtained MoC was further annealed in the air to obtain the MoC@MoO heterostructure. The SERS performance was evaluated by using a 532 nm laser as an excitation source and a rhodamine 6G (R6G) molecule as the Raman reporter. This process demonstrates that attractive SERS performance with a Raman enhancement factor (EF) of 1.445 × 10 (R6G@10 M) and a limit of detection of 10 M can be achieved. Furthermore, the mechanism of SERS performance improvement with the MoC@MoO is also investigated. HRTEM detection and XPS spectra reveal that part of the MoC is oxidized into MoO during the air-annealing process, and generates metal-semiconductor mixing energy bands in the heterojunction. Under the Raman laser irradiation, considerable hole-electron pairs are generated in the heterojunction, and then the hot electrons move towards MoO and subsequently transfer to the molecules, which ultimately boosts the Raman signal intensity.
表面增强拉曼散射（SERS）是一种非破坏性的光谱分析技术。它具有高检测性和灵敏度的优点，并且已经广泛研究用于痕量分子的检测。目前，一种基于非贵金属的 SERS 基底具有优异的增强能力和环境稳定性，可用于进行先进的生物分子检测。本文构建了一种碳化钼/氧化钼（MoC@MoO）异质结构，并通过促进电荷转移获得了有吸引力的 SERS 性能。实验上，首先通过在氩气气氛中煅烧钼酸铵四水合物和明胶混合物来制备 MoC。然后，将获得的 MoC 进一步在空气中退火以获得 MoC@MoO 异质结构。通过使用 532nm 激光作为激发源和罗丹明 6G（R6G）分子作为拉曼报告分子来评估 SERS 性能。该过程证明可以实现具有 1.445×10（R6G@10M）的拉曼增强因子（EF）和 10M 的检测限的有吸引力的 SERS 性能。此外，还研究了 MoC@MoO 提高 SERS 性能的机制。HRTEM 检测和 XPS 光谱表明，在空气退火过程中，部分 MoC 氧化成 MoO，并在异质结中产生金属-半导体混合能带。在拉曼激光照射下，异质结中会产生大量的空穴-电子对，然后热电子向 MoO 移动，并随后转移到分子上，从而最终增强了拉曼信号强度。
