Heavy Anionic Complex Creates a Unique Water Structure at a Soft Charged Interface

William Rock, Baofu Qiao, Tiecheng Zhou, Aurora E. Clark, Ahmet Uysal*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Ion hydration and interfacial water play crucial roles in numerous phenomena ranging from biological to industrial systems. Although biologically relevant (and mostly smaller) ions have been studied extensively in this context, very little experimental data exist about molecular-scale behavior of heavy ions and their complexes at interfaces, especially under technologically significant conditions. It has recently been shown that PtCl6 2- complexes adsorb at positively charged interfaces in a two-step process that cannot fit into well-known empirical trends, such as Hofmeister series. Here, a combined vibrational sum frequency generation and molecular dynamics study reveals that a unique interfacial water structure is connected to this peculiar adsorption behavior. A novel subensemble analysis of molecular dynamics simulation results shows that after adsorption PtCl6 2- complexes partially retain their first and second hydration spheres and that it is possible to identify three different types of water molecules around them on the basis of their orientational structures and hydrogen-bonding strengths. These results have important implications for relating interfacial water structure and hydration enthalpy to the general understanding of specific ion effects. This in turn influences interpretation of heavy metal ion distribution across, and reactivity within, liquid interfaces.

Original languageEnglish (US)
Pages (from-to)29228-29236
Number of pages9
JournalJournal of Physical Chemistry C
Volume122
Issue number51
DOIs
StatePublished - Dec 27 2018

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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