Surface enhanced Raman spectroscopy (SERS) is a popular method of organic molecules detection in low concentrations. Being close to each other, noble metal nanoparticles, such as gold and silver, form hot spots, which can enhance signal of Raman spectroscopy. To obtain substrates with high value of enhancement coefficient and good signal reproducibility, metal nanoparticles should be uniformly distributed on the substrate surface. That could be achieved using titania nanosheets as a sublayer. Titania nanosheets represent 2D photocatalytic material, which demonstrates strong bond with metal nanoparticles, and, therefore, is perspective in production of reusable substrates for SERS with reproducible signal on the surface.
In present research, titania nanosheets were obtained during cesium titanate exfoliation using solutions of hydrochloric acid and tetrabutylammonium hydroxide. The nanosheets show lateral sizes up to 1 µm and thickness of 0.5 nm, which proves the formation of single-layered titania nanosheets. Silver nanoparticles were deposited on the surface of nanosheets via AgNO3 solution reduction using sodium borohydride. The optimized synthesis of the substrates allows achieving enhancement coefficient up to 5·106 and ability to detects molecules of rhodamine 6G with concentration of 10-8 M. Moreover, investigation of SERS signal distribution throughout the surface shows high reproducibility of it. Due to photocatalytic properties of titania, surface of the substrates can be cleaned after measurement by UV irradiation, and the substrates can be used repeatedly.
