Highly sensitive and stable Ag nanoparticles decorated TiO2-ZrO2 composite SERS substrates for Rhodamine 6G detection

Abstract

Surface Enhanced Raman Scattering (SERS) has long been considered as a highly promising method for general and label free identification and single molecule sensing. In this technique, the Raman signals got enhanced enormously several times for probe molecules adsorbed on or near some roughened metal surfaces. Nano-plasmonic substrates coated over a binary metal oxide thin film is a key component in the persistent advances of SERS molecular analysis but also very much challenging to fabricate inexpensively on large scale. Herein, we synthesized TiO2-ZrO2 composite thin film using facile and cost-effective sol–gel assisted dip coating technique, to produce highly stable and sensitive SERS substrates. Layer by layer incorporation of silver nanoparticles on to TiO2-ZrO2 thin films with different molar concentrations has proved to act as an efficient SERS substrate,TiO2-ZrO2 thin film coated with 0.05 M Ag nanoparticle was the optimized excellent substrate. Since the density of electrons is more for corner shaped silver nanoparticles, the surface plasmon resonance is enhanced and hence the enhancement of Raman signals occurs. Rhodamine 6G in water is chosen as the probe molecule for the evaluation of Raman enhancement. Dye concentration up to 10-18 M (1 aM) detected using Raman analysis shows the high sensitive nature of the SERS substrate thin films.