In-Operando characterization of Electrochemical Interfaces Via Shiners: Shell-Isolated Nanoparticle Enhanced Raman Spectroscopy

Abstract

The advent of SERS created a new avenue for investigating interfacial phenomena by coupling the localized surface plasmon resonance (LSPR) of metal nanostructures to the inelastic scattering properties of molecules. Seeing a 104-fold enhancement in Raman signals, SERS scattering events were used to identify adsorbed molecules and substrate-surface structural conformations. But, even with the advent of SERs, Raman spectroscopy was still confined to LSPR active materials with roughened surfaces. However, recent technical modifications to SERS, such as shell-isolation and localized probe modes, have shown potential for the in-operando investigation of flat non-plasmon active single-crystal surfaces. Shell-isolated Nanoparticle Enhanced Raman Spectroscopy(SHINERS) provides two parallel paths for electric field enhancement of non-plasmon active surfaces while minimizing chemical perturbations by encasing reporters in a chemically inert shell (Figure 1). This technique can be used to perform in-operando measurements during electrochemical processes to bridge the gap between observing and understanding the state of metallic interfaces under an applied bias. This serve as a great utility to not only understand surface adsorbates, but to also characterize dynamic surfaces (e.g. Cu) that undergo reconstruction in response to the applied biases. Such metastable surfaces can impede capturing surface structure information, preventing accurate structure-activity assignments necessary to further understanding of the system. Furthermore, a lack of in-operando technology has inhibited the characterization of active sites and surface phenomena via in-situ measurements. These limitations have resulted in uncertainty of how novel findings are interconnected and ways to design refined interfaces. Herein, I report the synthesis of SiO2 encapsulated Au NPs and their application in-operando to track the state of Cu interfaces under varying electrochemical and chemical conditions. Figure 1