Recycling Ag SERS-substrates from strongly chemisorbing molecules

Area of Science:

• Analytical Chemistry
• Materials Science
• Spectroscopy

Background:

• Surface-Enhanced Raman Spectroscopy (SERS) offers high sensitivity for molecular detection.
• Current SERS substrates, often noble metal nanostructures, are typically single-use due to analyte chemisorption.
• Recycling SERS substrates is crucial for commercial usability and waste reduction.

Purpose of the Study:

• To develop and evaluate a plasma-based recycling method for silver (Ag) SERS substrates.
• To assess the impact of recycling on substrate performance and structural integrity.
• To demonstrate the removal of various analytes using the proposed cleaning procedure.

Main Methods:

• A two-step plasma cleaning procedure involving O2-plasma oxidation followed by H2-plasma reduction was employed.
• Silver SERS substrates were exposed to analytes: rhodamine 6G (R6G), 2-mercaptobenzothiazole (MBT), and 1,2-benzenedithiol (BDT).
• Substrate performance was evaluated over 20 recycling cycles using SERS, and structural changes were analyzed via SEM.

Main Results:

• The plasma cleaning procedure successfully removed all tested analytes from the Ag SERS substrates.
• Analytical Enhancement Factors (AEFs) initially increased for the first ten recycling steps, then decreased.
• SEM analysis correlated the observed AEF trend with nanoscale structural alterations of the substrate.

Conclusions:

• The presented O2/H2 plasma treatment is an effective method for recycling Ag SERS substrates.
• The recycling process influences substrate nanostructure and SERS performance over multiple cycles.
• This method contributes to waste reduction and enhances the reproducibility of SERS measurements.