Effect of Edge Charges on Stability and Aggregation of Ti3C2T z MXene Colloidal Suspensions

Varun Natu, Maxim Sokol, Louisiane Verger, Michel W. Barsoum

Research output: Contribution to journalArticlepeer-review

155 Scopus citations

Abstract

Herein, the stabilities of aqueous Ti3C2Tz (MXene) colloidal suspensions were studied as a function of pH and sodium chloride concentrations using ζ-potential and dynamic light scattering measurements. Complete sedimentation was observed when the pH was changed to 5 or 10. In the low pH regime, protons saturate the surface functional groups, rendering the ζ-potential less negative that, in turn, leads to aggregation. In the high pH regime, the ζ-potential remained constant up to a pH of almost 12. As the molarity of NaCl increases from 0 to 0.04, the ζ-potential goes from -35 to -22.5 mV. At a molarity of 0.02, sedimentation was observed. When the pH or NaCl concentration is high, sedimentation occurred, presumably, because of a reduction in the double-layer thickness. In all cases, the sediment comprised crumpled Ti3C2Tz flakes. After adding charged nanoparticles to the colloidal suspension, at neutral pH, subsequent transmission electron microscope micrographs showed that the negative gold nanoparticles preferred the edges, whereas the positive ones preferred the surfaces. The charge differences between the edges and faces open opportunities for direct edge or face-specific organic functionalizations, similar to work done on other two-dimensional materials.

Original languageEnglish
Pages (from-to)27745-27753
Number of pages9
JournalJournal of Physical Chemistry C
Volume122
Issue number48
DOIs
StatePublished - 6 Dec 2018
Externally publishedYes

ASJC Scopus subject areas

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

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