Direct Observation Of Ion Pairing At The Liquid/Solid Interfaces By Surface Enhanced Raman Spectroscopy

Abstract

Ion-pairing, the association of oppositely charged ionic species in solution and at liquid/solid interfaces has been proposed as a key factor for a wide range of physicochemical phenomena. However, experimental observations of ion pairing at the ligand/solid interfaces are challenging due to difficulties in differentiating ion species in the electrical double layer from that adsorbed on the solid surfaces. Using surface enhanced Raman spectroscopy in combination with electrolyte washing, we presented herein the first direct experimental evidence of ion pairing, the coadsorption of oppositely charged ionic species onto gold nanoparticles (AuNPs). Ion pairing reduces the electrolyte concentration threshold in inducing AuNP aggregation and enhances the competitiveness of electrolyte over neutral molecules for binding to AuNP surfaces. The methodology and insights provided in this work should be important for understanding electrolyte interfacial interactions with nanoparticles.

Publication Date

8-25-2015

Publication Title

Langmuir

Volume

31

Issue

33

Number of Pages

8998-9005

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1021/acs.langmuir.5b01903

Socpus ID

84939864407 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84939864407

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