Novel Au−Ag Hybrid Device for Electrochemical SE(R)R Spectroscopy in a Wide Potential and Spectral Range

Abstract

A nanostructured gold-silver-hybrid electrode for SER spectroelectrochemistry was developed which advantageously combines the electrochemical properties and chemical stability of Au and the strong surface enhancement of (resonance) Raman scattering by Ag. The layered device consists of a massive nanoscopically rough Ag electrode, a thin (2 nm) organic layer, and a ca. 20 nm thick Au film that may be coated by self-assembled monolayers for protein adsorption. The SERR-spectroscopic and electrochemical performance of this device is demonstrated using the heme protein cytochrome c as a benchmark model system, thereby extending, for the first time, SE(R)R studies of molecules on Au surfaces to excitation in the violet spectral range. The enhancement factor is only slightly lower than for Ag electrodes which can be rationalized in terms of an efficient transfer of plasmon resonance excitation from the Ag to the Au coating. This mechanism, which requires a thin dielectric layer between the two metals, is supported by theoretical calculations.

Ultrathin Diamond-like Carbon Film Coated Silver Nanoparticles-Based Substrates for Surface-Enhanced Raman Spectroscopy

“…Recently an AuϪAg hybrid device was developed in which Au/Ag was separated by an ultrathin insulating organic film using an electrochemical method. 6 This device was found to exhibit an enhancement nearly the same as that of the Ag surface. The mechanism can be attributed to an efficient transfer of plasmon resonance excitation from Ag to Au.…”

“…The principle of the method exploits mainly the enhancement of Raman scattering from the molecules in the proximity of nanoscale rough metal surfaces due to the coupling of an oscillating electric field of the incident and scattered radiation with surface plasmons of the metal. 6 A convenient way to build a SERS-active substrate is to use Ag or Au nanoparticles, 7,8 either in a solution or immobilized at a dielectric surface. 9,10 Ag is generally preferred over Au as a SERS active element because of its up to 2 orders of magnitude greater enhancement factor especially in the visible spectrum region.…”

Spatial dispersion in two-dimensional plasmonic crystals: Large blueshifts promoted by diffraction anomalies

“…From these results, a remarkable impact on high-Q sensing applications, quantum dot emitters, molecular decay rates, and absorption spectra in large-area nanostructured materials is anticipated. A nonlocal methodology for 2D PlCs can give a full account on the impact of nonlocal response for important concepts and applications in photonics, such as particle-array-enhanced spectroscopic methods [16][17][18]21,[54][55][56][57][58] and transmission through holey metal films. We show that additional pressure waves induced by the electron oscillation lead to a change in the band structure and electromagnetic fields supported by a plasmonic crystal.…”

Magnetic and noble metal nanocomposites for separation and optical detection of biological species

“…[100][101][102] The advantages of using nanoalloys in this context are the possibility of generating higher signal enhancement and improving biocompatibility. [103][104][105][106][107] This is particularly the case in applying silver to bio diagnostics. Silver can yield very high Raman enhancements and toxicity induced by silver can be mitigated by coating silver in gold.…”