RESUMO
The WO3 nanopores array was obtained by an anodization method in aqueous solution with addition of F- ions. Several factors affecting the final morphology of the samples were tested such as potential, time, and F- concentrations. The morphology of the formed nanopores arrays was examined by SEM microscopy. It was found that the optimal time of anodization process is in the range of 0.5-1 h. The nanopores size increased with the increasing potential. The XPS measurements do not show any contamination by F- on the surface, which is common for WOx samples formed by an anodization method. Such a layer was successfully modified by anisotropic gold trisoctahedral NPs of various sizes. The Au NPs were obtained by seed-mediated growth method. The shape and size of Au NPs was analysed by TEM microscopy and optical properties by UV-VIS spectroscopy. It was found that the WO3-Au platform has excellent SERS activity. The R6G molecules could be detected even in the range of 10-9 M.
RESUMO
The deposition of a layer of plasmonic metal on a surface of highly ordered nanostructured oxide is one of the important methods of preparation of substrates for surface-enhanced Raman scattering (SERS) measurements. In this contribution we describe formation of SERS substrates by the deposition of a gold layer on ordered ZrO2 nanotubes. The influence of various experimental parameters on the structure of formed composites and the achievable SERS enhancement factor has been analysed. Like commonly used SERS substrates formed by the deposition of plasmonic metals on TiO2 nanotubes, gold-covered ZrO2 nanotubes also could be used as reversible SERS platform after water rinsing: there is no any significant decrease in the SERS activity of the substrate even after 20 radiation-induced cleaning cycles. Moreover, SERS substrates formed on ZrO2 nanotubes are significantly more stable in strongly acidic media than the previously developed SERS substrates based on ordered TiO2 nanotubes.
