Constructing the Mo₂C@MoO_x Heterostructure for Improved SERS Application

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Surface-enhanced Raman scattering (SERS) offers high sensitivity for detecting trace molecules.
• Developing non-noble metal SERS substrates with excellent enhancement and stability is crucial for advanced applications.
• Molybdenum-based materials show potential for SERS applications.

Purpose of the Study:

• To construct a novel molybdenum carbide/molybdenum oxide (Mo2C@MoOx) heterostructure for SERS.
• To investigate the charge transfer mechanism enhancing SERS performance.
• To evaluate the substrate's sensitivity and stability for biomolecule detection.

Main Methods:

• Synthesis of Mo2C via calcination of ammonium molybdate tetrahydrate and gelatin in argon.
• Formation of Mo2C@MoOx heterostructure by annealing Mo2C in air.
• SERS performance evaluation using a 532 nm laser and Rhodamine 6G (R6G) as a reporter molecule.
• Characterization using High-Resolution Transmission Electron Microscopy (HRTEM) and X-ray Photoelectron Spectroscopy (XPS).

Main Results:

• Achieved a high Raman enhancement factor (EF) of 1.445 × 10^8 for R6G at 10^-8 M.
• Demonstrated a limit of detection (LOD) of 10^-8 M for R6G.
• Identified the formation of metal-semiconductor mixing energy bands in the heterojunction.
• Revealed that charge transfer, specifically hot electron transfer from Mo2C to MoOx and then to molecules, enhances the SERS signal.

Conclusions:

• The Mo2C@MoOx heterostructure serves as an effective non-noble metal SERS substrate.
• The enhanced SERS performance is attributed to efficient charge transfer facilitated by the heterojunction.
• This material holds promise for sensitive and stable trace molecule detection in various analytical applications.