Isotropic Iodide Adsorption Causes Anisotropic Growth of Copper Microplates

Myung Jun Kim, Mutya A. Cruz, Zihao Chen, Heng Xu, Micah Brown, Kristen A. Fichthorn, Benjamin J. Wiley

Research output: Contribution to journalArticlepeer-review

Abstract

Control over the shape of a metal nanostructure grants control over its properties, but the processes that cause solution-phase anisotropic growth of metal nanostructures are not fully understood. This article shows why the addition of a small amount (75-100 μM) of iodide ions to a Cu nanowire synthesis results in the formation of Cu microplates. Microplates are 100 nm thick and micronwide crystals that are thought to grow through atomic addition to {100} facets on their sides instead of the {111} facets on their top and bottom surfaces. Single-crystal electrochemical measurements show that the addition of iodide ions decreased the rate of Cu addition to Cu(111) by 8.2 times due to the replacement of adsorbed chloride by iodide. At the same time, the addition of iodide ions increased the rate of Cu addition to Cu(100) by 4.0 times due to the replacement of a hexadecylamine (HDA) self-assembled monolayer with the adsorbed iodide. The activation of {100} facets and passivation of {111} facets with increasing iodide ion concentration correlated with an increasing yield of microplates. Ab initio thermodynamics calculations show that, under the experimental conditions, a minority of iodide ions replaces an overwhelming majority of chloride and HDA on both Cu(100) and Cu(111). While Cu nanowire formation is predicted (and observed) in solutions containing chloride and HDA, the calculations indicate that a strong thermodynamic driving force occurs for {111} facet (and microplate) growth when a small amount of iodide is present, consistent with the experiment.

Original languageEnglish (US)
Pages (from-to)881-891
Number of pages11
JournalChemistry of Materials
Volume33
Issue number3
DOIs
StatePublished - Feb 9 2021

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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