Low-Cost Fabrication of Pt Thin Films with Controlled Nanostructures and Their Effects on SERS

Abstract

We fabricated nanostructured Pt thin films with two different morphologies and studied their effects on the Raman spectrum of rhodamine 6G. The syntheses were achieved by templating mesoporous silica thin films which are characterized by 8-nm-sized pore channels and 3-4-nmthick walls in two different orientations of the channels. Therefore, the resultant nanostructured Pt thin films are composed of Pt nanorods of 8 nm in diameter vertically standing in one morphology and horizontally lying in the other. The latter produced stronger Raman signals than the former. Simulations based the discrete-dipole approximation on model nanostructures showed that the horizontally lying nanorods produce stronger local electromagnetic field than the vertically standing ones, in agreement with the experimental observations.

Templated syntheses of Pt thin films with feature sizes of 3, 6 and 9 nm and their effects on SERS

“…One of the reasons for this may be that the closely spaced Pt nanorods interact with one another to extend the SPR to longer wavelengths. The extension of the SPR to longer wavelengths has been demonstrated experimentally and theoretically on Pt‐9.…”

“…Our group has introduced a novel method to create nanostructured thin films by using mesoporous silica thin films (MSTFs) as templates . Filling the pores with SERS‐active metals and removing the template can produce nanostructured thin films.…”

“…We have previously reported the SERS activity of nanostructured Pt films with the feature size of 9 nm focusing on the effects of the amount of Pt and the details of the nanostructures . In this study, we synthesized Pt thin films with the feature sizes controlled to be 3, 6 and 9 nm and investigated the effects of the feature size on SERS.…”

Synergistic Effects between Gold Nanoparticles and Nanostructured Platinum Film in Surface-Enhanced Raman Spectroscopy

“…Even in the cases of Au/Au_film and Au/Pt_film, because the metallic films have smooth surfaces, the analyte molecules spilled onto them will not contribute to the SERS. On the contrary, Pt NRs substrate itself is SERS-active thanks to its nanoscopic morphology . Therefore, the excess analyte molecules can contribute to the SERS adding to the SERS produced by those in the hot spots.…”

“…A scheme of synthesis and a scanning electron microscopy (SEM, JEOL JSM-7100) image of a nanostructured Pt thin film are in Figure S1. More details of the synthesis of MSTF and the nanostructured Pt thin film can be found in our previous papers. − …”