Two-Dimensional Amorphous Titanium Dioxide/Silver (TiO₂/Ag) Nanosheets as a Surface-Enhanced Raman Spectroscopy...

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical technique.
• Improving the sensitivity and chemical enhancement of SERS substrates is crucial for various applications.
• Titanium dioxide (TiO2) and silver (Ag) nanoparticles are known for their optical and catalytic properties.

Purpose of the Study:

• To investigate the chemical enhancement of amorphous semiconductors for SERS.
• To increase the sensitivity of SERS substrates using amorphous titanium dioxide (a-TiO2) and silver nanoparticles.
• To fabricate and characterize a novel 2D a-TiO2/Ag nanosheet SERS substrate.

Main Methods:

• Calcination of TiO2 precursors at different temperatures to obtain amorphous (a-TiO2) and crystalline (c-TiO2) nanosheets.
• Fabrication of a 2D a-TiO2/Ag nanosheet SERS substrate via electrostatic interaction.
• SERS detection of probe molecules (rhodamine 6G and malachite green) and contaminants.
• Finite-difference time-domain (FDTD) simulation to evaluate electromagnetic field enhancement.

Main Results:

• The a-TiO2/Ag nanosheet substrate demonstrated significantly higher SERS sensitivity compared to c-TiO2 or Ag nanoparticles alone.
• Achieved detectable concentration limits of 10^-11 M for rhodamine 6G and 10^-10 M for malachite green.
• Obtained an enhancement factor (EF) up to 1x10^8 and a limit of detection of 1x10^-8 M for 4-mercaptobenzoic acid and alizarin red.
• FDTD simulations indicated that a-TiO2 nanosheets contribute positively to the chemical enhancement of SERS.

Conclusions:

• The fabricated 2D a-TiO2/Ag nanosheet SERS substrate exhibits high sensitivity and repeatability.
• Amorphous TiO2 plays a beneficial role in the chemical enhancement mechanism of SERS.
• This work presents a promising approach for developing advanced SERS substrates for sensitive chemical detection.