Ionic effects in self-propelled Pt-coated Janus swimmers

Aidan Brown*, Wilson Poon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Colloidal particles partially coated with platinum and dispersed in H2O2 solution are often used as model self-propelled colloids. Most current data suggest that neutral self-diffusiophoresis propels these particles. However, several studies have shown strong ionic effects in this and related systems, such as a reduction of propulsion speed by salt. We investigate these ionic effects in Pt-coated polystyrene colloids, and find here that the direction of propulsion can be reversed by addition of an ionic surfactant, and that although adding pH neutral salts reduces the propulsion speed, adding the strong base NaOH has little effect. We use these data, as well as measured reaction rates, to argue against propulsion by either neutral or ionic self-diffusiophoresis, and suggest instead that the particle's propulsion mechanism may in fact bear close resemblance to that operative in bimetallic swimmers.

Original languageEnglish
Pages (from-to)4016-4027
Number of pages12
JournalSoft Matter
Volume10
Issue number22
Early online date11 Apr 2014
DOIs
Publication statusPublished - 14 Jun 2014

Keywords

  • HYDROGEN-PEROXIDE SOLUTIONS
  • ELECTROCHEMICAL OXIDATION
  • CATALYTIC DECOMPOSITION
  • PLATINUM-ELECTRODES
  • OXYGEN REDUCTION
  • ACIDIC MEDIA
  • SURFACES
  • ADSORPTION
  • PROPULSION
  • MECHANISM

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