Hongyan Yu,Yongxue Chen,Zhenyu Wen,Rensheng Wang,Sisi Jia,Wenjie Zhu,Yanping Song,Huanhuan Sun,Bingbing Liu
Pressure-induced surface-enhanced Raman spectroscopy (PI-SERS) has garnered significant attention as a subfield of SERS detection due to its capacity to regulate the band gap between molecules and substrates through pressure modulation. Currently, SERS detection primarily focuses on single molecules at atmospheric pressure with limited investigations conducted under high pressure conditions. Herein, we employed rose-shaped MoS2 nanoflowers as the SERS substrate and realized selective PI-SERS enhancement of R6G molecules in the binary (MV+R6G) and ternary (MV+R6G+RhB) systems. The MoS2 demonstrated an exceptionally low SERS detection limit of 5 × 10–6 M in binary and ternary systems with equimolar amounts of molecules. High-pressure experimental results indicate that MoS2 displays selective enhancement for R6G molecules, as evidenced by the comparison of the PI-SERS peak intensity ratio between MoS2 and the probe molecules. The proposed enhancement mechanism in binary and ternary SERS systems under high pressure involves pressure-induced changes in both the band structures of the MoS2 substrate and molecules, thereby influencing their charge transfer dynamics. Consequently, this approach holds great promise for practical applications in complex SERS systems operating under extreme conditions.
Huanhuan Sun,Hongyan Yu,Boyang Han,Junjie Ma,Rensheng Wang,Yanping Song
Pressure-induced surface-enhanced Raman spectroscopy (PI-SERS) is among the foremost achievements of high-pressure fields, benefiting from the advantage that pressure-modulated interactions between substrates and molecules overcome the weakness of individual substrates or molecules. However, the pressure corresponding to PI-SERS enhancement is currently still at a low-pressure stage within 8 GPa. Therefore, how to realize PI-SERS enhancement under higher or ultrahigh pressure remains a huge challenge. Here, we applied few-layer WS2 (FL-WS2) nanosheets as PI-SERS substrates and selected 4-mercaptobenzoic acid (4-MBA) molecules with a big energy gap as probes to explore PI-SERS enhancement in more depth. The experimental results indicate that the PI-SERS signals increase gradually as pressure increases and reaches a maximum at 18 GPa, which has set a pressure record for the PI-SERS field so far. Different from the C exciton resonance-induced SERS intensities at ambient conditions, the charge-transfer transition between FL-WS2 and 4-MBA is strengthened via the pressure-induced increase in the band gap of FL-WS2 and decrease in the highest-occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gap of 4-MBA, thus enhancing PI-SERS signals accordingly. Therefore, this strategy will be beneficial for practical applications in the field of optoelectronics and for the design of other PI-SERS sensors for trace detection in complex and extreme environments.
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