Photocatalytical decoration of thin titania coatings with silver nanostructures provides a robust and reproducible SERS signal

Abstract

AbstractCost‐effective photocatalytic synthesis was used to fabricate silver nanostructures (AgNSs) on TiO2 coatings (AgNSs/TiO2) with plasmonic properties. In this study, the AgNSs growth controlled by variation of the concentration of Ag+ ions, hole scavengers, and ultraviolet illumination was systematically studied in terms of morphological characterization, extinction, and surface‐enhanced Raman spectroscopy (SERS). These structures with well‐defined and high photocatalytic properties show a plethora of shapes (from spherical to polygonal objects), diameter (8–108 nm), and surface coverage (12–62%). Morphological properties strongly affect nanoplasmonic features as revealed by electronic and SERS spectra. Surface enhancement of Raman signal was probed by using 4‐mercaptobenzoic acid to elucidate the stability and uniformity of the designed substrates. A detailed examination and correlation of geometrical parameters and SERS performance indicate synergistic contribution of the formation of hot spots between AgNSs. Some of the fabricated AgNSs present a very good homogeneity and reproducibility as well as long‐time stability. The highest enhancement factor in SERS was obtained for the Ag–TiO2 hybrids with a diameter and surface coverage of AgNSs less than 30 nm and larger than 50%, respectively.