Recyclable Au-TiO₂ nanocomposite SERS-active substrates contributed by synergistic charge-transfer effect

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Surface-Enhanced Raman Spectroscopy (SERS) requires efficient substrates for enhanced signal detection.
• Titanium dioxide (TiO2) nanoparticles (NPs) offer a versatile platform for developing novel SERS substrates.
• Noble metal deposition on semiconductors can lead to synergistic effects for improved SERS performance.

Purpose of the Study:

• To prepare and characterize Au-TiO2 nanocomposites as effective SERS-active substrates.
• To investigate the influence of preparation parameters on SERS enhancement.
• To evaluate the stability and reusability of the Au-TiO2 nanocomposite substrates.

Main Methods:

• Photocatalytic reduction of gold (Au) species (HAuCl4) onto TiO2 NPs to form Au-TiO2 nanocomposites.
• SERS measurements using 4-mercaptobenzoic acid (4-MBA) as a probe molecule.
• Characterization of substrate properties, including self-cleaning and stability.

Main Results:

• Au-TiO2 nanocomposites demonstrated significantly enhanced SERS signals compared to pure TiO2 NPs.
• The charge-transfer mechanism between the semiconductor and metal components contributed to the SERS enhancement.
• Optimal photo-reduction time and HAuCl4 concentration were found to be crucial for maximizing SERS enhancement.
• The Au-TiO2 nanocomposite substrates exhibited excellent self-cleaning properties and stability for repeated SERS analyses.

Conclusions:

• Au-TiO2 nanocomposites are efficient and reusable SERS-active substrates.
• The synergistic effect between Au and TiO2 is key to the enhanced SERS performance.
• The self-cleaning property of these nanocomposites allows for long-term, stable SERS applications.