Enhanced Electrochemical Dark-Field Scattering Modulation on a Single Hybrid Core–Shell Nanostructure

We study the in situ electrochemically modulated dark-field scattering of a gold nanoparticle (AuNP) coated with the poly(3,4-ethylenedioxythiophene) (PEDOT) shell, allowing for the visualization of the oxidation–reduction (redox) state of PEDOT down to a single-nanoparticle level. The presence of the gold nanoparticle as a core dramatically increases scattering cross-section, which enables the visible detection of electrochemically induced modulation, a phenomenon otherwise is not observable in dark-field microscopy of pure PEDOT nanostructures. The dynamic modulation of AuNP@PEDOT core–shell nanostructures with a diameter of 100 nm is investigated for individual nanoparticles. In contrast to pure PEDOT nanoparticles with nondetectable changes, a significant 2-fold reversible increase in scattering peak intensity is revealed for the single-hybrid nanoparticle when the PEDOT shell is switched from its doped state to its dedoped state. Further in situ analysis of the core–shell nanostructures with PEDOT sh...