Hybrid Gold Nanoparticle–Polyoxovanadate Matrices: A Novel Surface Enhanced Raman/Surface Enhanced Infrared Spectroscopy Substrate

Abstract

Bare gold nanoparticles were embedded into an iron-polyoxovanadate matrix and used to enhance both the infrared and Raman signatures of a model analyte. A detailed characterization of the matrix-embedded nanoparticles revealed that they retained a plasmon resonance at 564 nm. The enhancement of vibrational signatures of the model analyte crystal violet using bare and embedded gold nanoparticles was compared for both surface enhanced infrared (SEIRA) spectroscopy and surface enhanced Raman spectroscopy (SERS) yielding enhancement factors of 2.2 for SEIRA and 77 for SERS. In contrast, the bare gold nanoparticles revealed significantly lower enhancements (1.6 for SEIRA; 20 for SERS). Hence, it was shown that embedding nanoparticles within an inorganic polyoxometalate-based matrix is an innovative strategy to amplify their signal enhancement properties in vibrational spectroscopies.

Recent Advances in Hybrid Materials of Metal Nanoparticles and Polyoxometalates

“…To date, two possible explanations have been proposed: either an improvement of the enhancement factor of crystal violet during the SERS studies [33] or the electrostatic interaction between the positively charged substrates and negatively charged POMs is important. [38] For further application of these novel materials in the field of SERS, more thorough mechanistic studies are required. This is particularly important considering that SERS is an efficient and useful tool for the determination of the surface states and growth mechanisms of nanostructures because of its high sensitivity, especially when combined with other characterization techniques such as electron microscopy.…”

“…This research field started from a pioneering study where SERS was used to determine strong metal–ligand interactions between the POM ligands and the Ag nanoparticles [7h] . Following this study, SERS‐active POM‐modified metal nanoparticles with high selectivity toward different substrates have been developed [33–38] . Although these hybrid materials have been applied in SERS studies, the investigation of the origin of the SERS effect in POMs is still in progress.…”

“…Although these hybrid materials have been applied in SERS studies, the investigation of the origin of the SERS effect in POMs is still in progress. To date, two possible explanations have been proposed: either an improvement of the enhancement factor of crystal violet during the SERS studies [33] or the electrostatic interaction between the positively charged substrates and negatively charged POMs is important [38] . For further application of these novel materials in the field of SERS, more thorough mechanistic studies are required.…”

“…[7h] Following this study, SERS-active POM-modified metal nanoparticles with high selectivity toward different substrates have been developed. [33][34][35][36][37][38] Although these hybrid materials have been applied in SERS studies, the investigation of the origin of the SERS effect in POMs is still in progress. To date, two possible explanations have been proposed: either an improvement of the enhancement factor of crystal violet during the SERS studies [33] or the electrostatic interaction between the positively charged substrates and negatively charged POMs is important.…”

Surface-Enhanced Infrared Absorption Spectroscopy for Analyzing Nucleophilic Molecules Using Ethylene Glycol Decorated TiO2 Nanosheet

“…The SEIRA active substrates are usually antenna arrays and noble metals with abundant conduction electrons, which exhibit surface plasmon resonance (SPR) in the infrared region, coupling with the molecular vibrations of the analytes. ,− Recently, the SEIRA active substrates have extended to two-dimensional (2D) materials such as graphene and graphene oxides. These substrates mainly take advantage of chemical mechanisms (CM), ,− which originated from the electron or charge transfer between analytes and substrates. Specifically, the π–π stacking interactions between the delocalized π orbitals of the substrates and the aromatic moieties of the analytes contributed to the SEIRA effects by accumulating the analytes and facilitating the charge transfer (CT). , Inspired by the SEIRA effect of graphene and graphene oxide, we propose that 2D metal oxide may be a potential SEIRA substrate.…”