title: Simple synthesis and size-dependent surface-enhanced Raman scattering of Ag nanostructures on TiO2 by thermal decomposition of silver nitrate at low temperature.
abstract: A low-temperature dry-process was proposed to synthesize silver nanoparticles, nanorods, and nanoplates on TiO(2) films via thermal decomposition of silver nitrate. X-ray diffraction (XRD) shows only silver crystals were synthesized on the substrate without other byproducts remaining. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveal the Ag nanoparticles are single-crystalline face-centered cubic (FCC) structures and their average diameters decrease from 100 to 15 nm with the increase in distance from the source, which corresponds to a decrease of substrate temperature from 350 to 110 degrees C. The Ag nanorods are also single-crystalline FCC structures growing along the [110] direction with diameter and length around 40 and 500 nm, respectively. The morphology of silver nanostructures could be adjusted by varying the working pressure as well as the roughness of the substrates. An obvious size-dependent SERS effect on the TiO(2) substrate with silver nanoparticles was observed for the first time. The enhancement factor increases as the size of the Ag nanoparticles decreases, which is attributed to the increase of hot spots. In addition, fractional brookite in the anatase films could be detected only after being loaded with Ag nanoparticles, which demonstrates the application of SERS in detecting fractional and important features of semiconductors.
authors.affiliation: Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan. rcwang@nuk.edu.tw
authors.forename: Ruey-Chi
authors.initials: RC
authors.lastname: Wang
authors.forename: Yong-Siang
authors.initials: YS
authors.lastname: Gao
authors.forename: Shu-Jen
authors.initials: SJ
authors.lastname: Chen
mesh_terms: D003080:Cold Temperature; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D012834:Silver / Q000737:chemistry*; D012835:Silver Nitrate / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: C009495:titanium dioxide; D012834:Silver; D012835:Silver Nitrate; D014025:Titanium