Reversible light-dependent molecular switches on Ag/AgCl nanostructures

The Origin of Mo2C Films for Surface-Enhanced Raman Scattering Analysis: Electromagnetic or Chemical Enhancement?

The relatively weak Raman enhanced factors of semiconductor-based substrate limit its further application in surface-enhanced Raman scattering (SERS). Here, a kind of two-dimensional (2D) semimetal material, molybdenum carbide (Mo₂C) film, is prepared via a chemical vapor deposition (CVD) method, and the origin of SERS is investigated for the first time. The detection limits of the prepared Mo₂C films for crystal violet (CV) and rhodamine 6G (R6G) molecules are low at 10^-6 M and 10^-8 M, respectively. Our detailed theoretical analysis, based on density functional theory and the finite element method, demonstrates that the enhancement of the 2D Mo₂C film is indeed CM in nature rather than the EM effects. Besides, the basic doping strategies are proposed to further optimize the SERS sensitivity of Mo₂C for Fermi level regulation. We believe this work will provide a helpful guide for developing a highly sensitive semimetal SERS substrate.

Highly efficient core–shell Ag@carbon dot modified TiO2 nanofibers for photocatalytic degradation of organic pollutants and their SERS monitoring

The possible mechanism of enhanced photocatalytic performance of Ag@CDs–TiO₂ hybrid NFs.

Plasmonic Cu/CuCl/Cu2S/Ag and Cu/CuCl/Cu2S/Au Supports with Peroxidase-Like Activity: Insights from Surface Enhanced Raman Spectroscopy

In the present study, we present nanostructured bimetallic Cu/CuCl/Cu2S/Au(Ag) supports that exhibit plasmonic electromagnetic field enhancement and peroxidase-like catalytic activity. The Cu2S component acts as the peroxidase-like catalyst, while the Au or Ag component provides the necessary light enhancement for surface enhanced Raman spectroscopic (SERS) studies of surface bound molecular reactants. As a test reaction the catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in presence of H2O2 was investigated. The comparison of product evolution in solution measured by UV-Vis spectroscopy and on the surface measured via SERS is able to give more insight into the different steps involved in the overall catalysis.

Near-field chemical mapping of gold nanostructures using a functionalized scanning probe

We report on photochemical and photophysical properties produced by Surface Plasmon Resonance (SPR) on metallic nanograins by means of high resolution Functionalized Tip-Enhanced Raman Spectroscopy (F-TERS). This technique relies on a sharp gold tip functionalized with Raman-active molecules to be scanned relatively to plasmonic hot-spots on a surface. We describe the local variation of plasmon-induced Raman enhancement on the surface of nanostructures that also affects the photochemistry while the quantitative interpretation of peak intensities requires the consideration of surface topography near the tip apex. Our F-TERS maps show Raman modes of hot electron reduction of 4-nitrothiophenol (4-NTP) molecules on the tip and indicate at least partial photochemical dimerization. An apparent photo-induced reversibility of this dimerization can be conservatively explained by a local topography feature that we simulate in a finite element environment. Our experimental results reveal a spatial resolution of approximately 10 nm, corresponding to a few hundred 4-NTP molecules exposed to the near-field.

A molecular quantum switch based on tunneling in meta-d-phenol C6H4DOH

The concept of a molecular quantum switch is introduced from realistic, quantitative wavepacket analyses of tunneling switching in m-d-phenol.

Bi-functional reduced graphene oxide/AgCo composite nanosheets: an efficient catalyst and SERS substrate for monitoring the catalytic reactions

We describe the fabrication of bifunctional rGO/AgCo composite nanosheets as SERS substrates to monitor catalytic and photocatalytic reaction.