Quantitative Label-Free and Real-Time Surface-Enhanced Raman Scattering Monitoring of Reaction Kinetics Using Self-Assembled Bifunctional Nanoparticle Arrays

Abstract

Although surface-enhanced Raman scattering (SERS) has proven to be an effective tool for label-free monitoring of catalytic reactions, quantitative characterization of reaction kinetics via this technique remains challenging owing to the difficulty in integrating catalytic and plasmonic activities into a single platform. In this work, we report on an easy access to highly sensitive plasmonic nanoarrays for direct and label-free monitoring of a gold-catalyzed reaction by SERS. The hierarchically structured three-dimensional assemblies, which consist of small gold catalyst nanoparticles distributed on a self-assembled monolayer of larger gold nanoparticles, were formed through a simple and rapid stepwise interfacial self-assembling process (fabrication time <10 min). The well-defined interparticle distances (<1 nm) lead to efficient plasmonic coupling and ensure both catalytic and SERS-active sites exposed to the environment. Such a versatile bifunctional platform thus allows quantitative determination of the rate constant and activation energy of the catalytic reaction with SERS.

Two different behaviors in 4-ABT and 4,4′-DMAB surface enhanced Raman spectroscopy

“…[26] However, it is biasedly reported in recent literatures that only the photoproduct mechanism has been accepted as a more convincing interpretation than other mechanism. [27][28][29][30][31][32][33][34][35][36][37][38] Here, I report two evidences to support the CHEM mechanism in 4-ABT SERS.…”

Tracking the Fate of Surface Plasmon Resonance‐Generated Hot Electrons by In Situ SERS Surveying of Catalyzed Reaction

“…The key step for the p‐NTP reduction is to break the NO bonds, and converse into p‐ABT through intermediates like dihydroxylaminobenzenethiol (DHABT), nitrosobenzenethiol (NSBT), hydroxylaminobenzenethiol (HABT), azoxybenzenethiol (AZOBT), and dimercaptohydroazobenzene . Normally, this process is realized by the active H species, approximately, H‐Pd, with an activation energy of no more than 100 kJ mol −1 . However, under the excitation of light, the generated HEs may migrate into the antibond orbit of the nitro groups, and facilitates their cleavage (Scheme S2, Supporting Information).…”

Surface‐Enhanced Raman Spectroscopy as a Probe of the Surface Chemistry of Nanostructured Materials

“…reduction of p-nitrothiophenol to p-aminothiophenol by NaBH4 to be monitored. [33] Similarly, SERS can be used as an in situ spectroelectrochemical probe of the active speces and products formed on electrode surfaces. [34] In a more complex example, Ling et al prepared a layer of Ag nanocrystals protected by a thin alumina layer onto which was deposited a layer of TiO2 nanoplates decorated with Pt co-catalyst nanoparticles.…”