Single Molecule Electrochemistry: Impact of Surface Site Heterogeneity

Bo Fu, Colin Van Dyck*, Stephanie Zaleski, Richard P. Van Duyne, Mark A. Ratner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Probing the electrochemistry of single molecules is a direct pathway toward a microscopic understanding of a variety of electron transfer processes related to energy science, such as electrocatalysis and solar fuel cells. In this context, Zaleski et al. recently studied the single electron transfer reaction of the dye molecule rhodamine-6G (R6G) by electrochemical single molecule surface-enhanced Raman spectroscopy (EC-SMSERS) (J. Phys. Chem. C 2015, 119, 28226-28234). In that work, the reductions of the dye molecule R6G were not only observed in the same potential range as in the ensemble surface cyclic voltammogram but also seen under some less negative potentials. Aiming to understand and explain this experiment theoretically, we relate the binding energy of R6G+ adsorbed on a silver nanoparticle (AgNP) to its reduction potential and further use periodic density functional theory to calculate this adsorption energy at different local surface sites. Well-defined crystal facets and defective surfaces, are considered. We find that the calculated adsorption energy distribution of the strongest binding states at each surface site closely matches the potential range of the experimentally observed Faradaic events. Moreover, the underpotential events are explained by the metastable adsorption states with less binding strength compared with those corresponding to Faradaic events. Our study reveals the importance of the heterogeneity of surface structures on the AgNP and offers a new perspective on understanding single molecule electrochemical behavior. (Graph Presented).

Original languageEnglish (US)
Pages (from-to)27241-27249
Number of pages9
JournalJournal of Physical Chemistry C
Volume120
Issue number48
DOIs
StatePublished - Dec 8 2016

Funding

This work was supported by Air Force Office of Scientific Research MURI (FA9550-14-1-0003). We gratefully acknowledge the computational resources from the Quest high performance computing facility at Northwestern University and the Extreme Science and Engineering Discovery Environment (XSEDE) Program, which is supported by National Science Foundation Grant ACI-1053575. S.Z. acknowledges Michael Mattei for helpful discussions.

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Fingerprint

Dive into the research topics of 'Single Molecule Electrochemistry: Impact of Surface Site Heterogeneity'. Together they form a unique fingerprint.

Cite this