Ultrasensitive Surface-Enhanced Raman Spectroscopy Detection Based on Amorphous Molybdenum Oxide Quantum Dots

Area of Science:

• Materials Science
• Spectroscopy
• Nanotechnology

Background:

• Surface-enhanced Raman spectroscopy (SERS) is effective for trace substance detection.
• Plasmonic semiconductive materials offer potential for SERS but have weaker resonance than noble metals.
• Weak plasmon resonance limits the practical application of semiconductive SERS materials.

Purpose of the Study:

• To develop a facile method for fabricating amorphous HxMoO3 quantum dots with tunable plasmon resonance.
• To investigate the tunability of plasmon resonance in amorphous HxMoO3 quantum dots.
• To evaluate the performance of amorphous HxMoO3 quantum dots as SERS substrates for high-precision molecule detection.

Main Methods:

• Fabrication of amorphous HxMoO3 quantum dots via a controlled oxidization route.
• Characterization of plasmon resonance in the visible and near-infrared regions.
• Analysis of tunability induced by supercritical CO2 using molecular kinetic and thermodynamic models.
• SERS detection of methyl blue, Rhodamine 6G (Rh6G), and Rhodamine B (RhB) using HxMoO3 quantum dots.

Main Results:

• Amorphous HxMoO3 quantum dots with tunable plasmon resonance were successfully fabricated.
• Tunable plasmon resonance was observed in the visible and near-infrared light regions.
• An ultrahigh enhancement factor of up to 9.5 × 10^5 was achieved for methyl blue detection.
• The limit of detection was extended to 10^-9 M for methyl blue.
• Similar high performance was observed for Rh6G and RhB detection, indicating broad applicability.

Conclusions:

• Amorphous HxMoO3 quantum dots are a promising plasmonic semiconductive material for SERS.
• The developed fabrication method provides tunable plasmon resonance for enhanced SERS applications.
• These quantum dots enable high-precision trace molecule detection with an ultrahigh enhancement factor.