Electrodeposited Gold Nanodaggers on Conductive Metal Oxide Films Provide Substrates for Dual-Modality Surface Sensitive Vibrational Spectroscopy

Abstract

Dagger shaped gold particles have been electrodeposited on surfaces of conductive indium tin oxide (ITO) films. The optical extinction of these AuND@ITO substrates extends from the near-IR to long wavelength mid-infrared frequencies. AuND@ITO substrates are assessed as potential enhancing interfaces for dual modality, spectroelectrochemical, surface sensitive vibrational spectroscopy; specifically surface enhanced Raman spectroscopy (SERS) using 1064 nm excitation and attenuated total reflectance surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) using a broadband emission source. The potential dependent spectra of pyridine establishes the SERS suitability of the AuND@ITO interfaces and confirms the N-bonded adsorption model. The ability of the substrates to provide surface enhancement for both SERS and ATR-SEIRAS allows an analogous study of 4methoxypyridine (MOP) and, with the assistance of DFT calculations and surface selection rules, demonstrates that MOP adsorbs with a vertical orientation over a broad range of applied potentials. In a proof of principle experiment, the SEIRAS and SERS spectra of the same self-assembled monolayer of 4-mercaptobenzoic acid (MBA) is reported using a AuND@ITO film supported on a ZnSe hemisphere.

Nanostructured Black Silicon as a Stable and Surface-Sensitive Platform for Time-Resolved In Situ Electrochemical Infrared Absorption Spectroscopy

“…Six distinct signals in the range between 1000 and 1700 cm –1 are visible for all cases and are consistent with those previously observed from a MOP monolayer adsorbed at a polycrystalline Au/electrolyte interface. , The observed vibrational modes correspond to in-plane ( A ′) vibrations of the MOP molecule, with those at 1615, 1562, 1509, and 1211 cm –1 attributable to υ 8a , υ 8b , υ 19a , and υ 9a ring vibrations, respectively . The 1308 cm –1 signal can be assigned to the asymmetric C–O–C stretching vibration of the methyl group and that at 1030 cm –1 can be attributed to an in-plane ring breathing vibration υ 12 of the MOP …”

Review on Silver Nanoparticle Synthesis Method, Antibacterial Activity, Drug Delivery Vehicles, and Toxicity Pathways: Recent Advances and Future Aspects

“…Fungal-Derived Synthesis. Polydispersed spherical Agnips ranging in dimension from 17-33 nm were produced utilizing Helminthosporium tetramer cell-free filtration and demonstrated substantial antibacterial activity [26]. Escherichia coli has been reported to become more vulnerable than S. aureus to silver nanoparticles [27].…”

Surface sensitive infrared spectroelectrochemistry using palladium electrodeposited on ITO-modified internal reflection elements

“…MOP, like its parent pyridine compound, can on metal surfaces in different orientations depending on the electrolyte acidity, and the electronic state and crystallography of the metal surface. 42 The two limiting MOP adsorption motifs on gold are end-on (s bonding through the ring N atom) and flat-lying (bonding with the metal through the molecular p-orbitals) as confirmed through ATR-SEIRAS 41 and SERS 31 experiments. Previous surface enhanced vibrational spectroscopy studies have shown intact, edge-tilted orientations for pyridine adsorption on transition metals such as Ru 51 and Rh, 51,52 whereas strong evidence exists for a-pyridyl on Pt 51,[53][54][55][56] (see Fig.…”

“…[26][27][28] Thin films of indium zinc oxide (IZO) 27 or indium tin oxide (ITO) 26,29,30 were shown to have the free charge carrier density and mobility to be sufficiently conductive to allow electrodeposition of gold island films from solutions of gold salt precursor. Gold films on CMO (Au@CMO) give strong ATR-SEIRAS (and SERS) signals 31 and are remarkably robust compared to metal films directly deposited on IRE surfaces, which are highly susceptible to film delamination under electrochemical conditions. 19 In this report, we extend the use of CMOs for ATR-SEIRAS to palladium and describe a reproducible means to monitor the SEIRAS activity of Pd@ITO surfaces during electrodeposition.…”