Tailored FTO/Ag/ZIF-8 structure as SERS substrate for ultrasensitive detection

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Surface-enhanced Raman scattering (SERS) is a powerful analytical technique for molecular detection.
• Developing highly sensitive and stable SERS substrates is crucial for practical applications.
• Zeolite imidazole framework (ZIF-8) materials offer unique properties for molecular adsorption and interaction.

Purpose of the Study:

• To fabricate and optimize a novel F-doped SnO2/Ag/ZIF-8 sandwich structure as a SERS substrate.
• To investigate the synergistic enhancement mechanisms (electromagnetic and charge-transfer) in the fabricated substrate.
• To evaluate the SERS performance, including sensitivity, detection limit, and stability, for 4-mercaptobenzoic acid (4-MBA) detection.

Main Methods:

• Fabrication of F-doped SnO2/Ag/ZIF-8 sandwich structures using magnetic sputtering.
• Optimization of silver nanoparticle (Ag NPs) sputtering time for maximum SERS performance.
• SERS experiments using 4-mercaptobenzoic acid (4-MBA) as the probe molecule.

Main Results:

• The optimal FTO/Ag/ZIF-8 substrate was achieved with 120s Ag sputtering time, exhibiting maximum SERS performance.
• Synergistic effects of electromagnetic (EM) and charge-transfer (CT) mechanisms were observed, enhancing SERS signals.
• An exceptionally high enhancement factor (EF) of 7.67 × 10^6 and a low detection limit of 10^-9 M for 4-MBA were achieved.
• The SERS substrate demonstrated excellent stability, with signals remaining unchanged after 6 months of natural storage.

Conclusions:

• The FTO/Ag/ZIF-8 sandwich structure serves as a highly sensitive and stable SERS substrate.
• The combined EM and CT mechanisms contribute significantly to the enhanced SERS performance.
• This work holds potential for broadening the practical applications of SERS in various fields due to its high sensitivity and stability.