Citrate Coordination and Bridging of Gold Nanoparticles: The Role of Gold Adatoms in AuNP Aging.


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Article
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Authors
Grys, David-Benjamin  ORCID logo  https://orcid.org/0000-0002-4038-6388
de Nijs, Bart 
Huang, Junyang 
Wang, Wenting 
Abstract

Gold nanoparticles used in many types of nanostructure are mostly stabilized by citrate ligands. Fully understanding their dynamic surface chemistry is thus essential for applications, particularly since aging is frequently a problem. Using surface-enhanced Raman spectroscopy in conjunction with density functional theory calculations, we are able to determine Au-citrate coordination in liquid with minimal invasiveness. We show that citrate coordination is mostly bidentate and simply controlled by its protonation state. More complex binding motifs are caused by interfering chloride ions and gold adatoms. With increasing age of stored gold nanoparticle suspensions, gold adatoms are found to move atop the Au facets and bind to an additional terminal carboxylate of the citrate. Aged nanoparticles are fully refreshed by removing these adatoms, using etching and subsequent boiling of the gold nanoparticles.

Description
Keywords
SERS reproducibility, capping agent, citrate binding, colloidal gold, gold atom movement, ligand, nanogap
Journal Title
ACS Nano
Conference Name
Journal ISSN
1936-0851
1936-086X
Volume Title
14
Publisher
American Chemical Society (ACS)
Rights
All rights reserved
Sponsorship
EPSRC (1783357)
Engineering and Physical Sciences Research Council (EP/H007024/1)
Engineering and Physical Sciences Research Council (EP/L027151/1)
Engineering and Physical Sciences Research Council (EP/P029426/1)
Engineering and Physical Sciences Research Council (EP/R020965/1)
Isaac Newton Trust (18.08(K))
Leverhulme Trust (ECF-2018-021)
Engineering and Physical Sciences Research Council (EP/L015889/1)
Engineering and Physical Sciences Research Council (EP/G060649/1)
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