High-Performance Real-Time SERS Detection with Recyclable Ag Nanorods@HfO₂ Substrates

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Surface-enhanced Raman scattering (SERS) requires stable and efficient substrates for sensitive analyte detection.
• Existing SERS substrates often lack thermal stability and recyclability, limiting their practical applications.
• Developing robust and reusable SERS platforms is crucial for cost-effective sensing solutions.

Purpose of the Study:

• To develop a versatile, robust, and easily recyclable SERS substrate using silver nanorods coated with a hafnium oxide shell (Ag NRs@HfO2).
• To investigate the thermal stability, SERS activity, and reusability of the novel Ag NRs@HfO2 substrate.
• To demonstrate the substrate's capability for detecting analytes in both liquid and vapor phases at ultralow concentrations.

Main Methods:

• Synthesis of silver nanorods (Ag NRs) coated with an ultrathin hafnium oxide (HfO2) shell.
• Characterization of the Ag NRs@HfO2 composite substrate's structural and plasmonic properties.
• Evaluation of the substrate's SERS activity, thermal stability, and recyclability through multiple detection-heating cycles.
• Testing the substrate for real-time monitoring of vapor-phase samples and detection in liquids.

Main Results:

• The Ag NRs@HfO2 substrate exhibited excellent thermal stability due to the high melting point of the HfO2 shell, preserving the plasmonic efficiency of Ag NRs.
• The substrate demonstrated extraordinary SERS activity and maintained its efficiency over multiple cycles of analyte detection and thermal regeneration.
• Successful detection of analytes in both aqueous solutions and real-time monitoring of vapor-phase samples at ultralow concentrations were achieved.
• The regeneration process, involving annealing for several seconds, effectively removed adsorbed molecules, refreshing the substrate for subsequent measurements.

Conclusions:

• The Ag NRs@HfO2 composite serves as a versatile, robust, and cost-effective SERS sensor.
• The substrate's high sensitivity, stability, and recyclability make it suitable for practical applications in environmental, industrial, and homeland security sensing.
• This work presents a significant advancement in developing renewable SERS platforms for diverse analytical challenges.