Mesoporous plasmonic nanocomposites based on Au/Ag-TiO2 aerogels as SERS substrates

Au/Ag-TiO2 mesoporous nanocomposite aerogels are special materials that can be applied as efficient surface-enhanced Raman spectroscopy (SERS) substrates, in order to detect low concentration of analytes from aqueous environments. At the same time, they benefit from structural and intrinsic properties of aerogels and TiO2, respectively, and also the plasmonic effects of Au/Ag nanoparticles. Here, several composites of TiO2 aerogel modified with various concentrations of Au, Ag, and a mixture of Au-Ag nanoparticles were prepared by applying two different methods of synthesis. The SERS detection efficiency of the nanocomposites was established by using the dye crystal violate (CV) as the test molecule. The lowest concentration of CV detectable by SERS, which was 10-10 M, was found to depend on the method of synthesis, size, and type of the nanoparticles that were used in the nanocomposite structure. In addition, the morphological and structural characterizations of the nanocomposites were investigated through Brunauer-Emmet-Teller results, field emission scanning electron microscopy (FESEM), and transmission electron microscope images.