Jump to main content
Jump to site search


Real-time plasmon spectroscopy study of the solid-state oxidation and Kirkendall void formation in copper nanoparticles

Author affiliations

Abstract

Oxidation and corrosion reactions have a major effect on the application of non-noble metals. Kinetic information and simple theoretical models are often insufficient for describing such processes in metals at the nanoscale, particularly in cases involving formation of internal voids (nano Kirkendall effect, NKE) during oxidation. Here we study the kinetics of solid-state oxidation of chemically-grown copper nanoparticles (NPs) by in situ localized surface plasmon resonance (LSPR) spectroscopy during isothermal annealing in the range 110–170 °C. We show that LSPR spectroscopy is highly effective in kinetic studies of such systems, enabling convenient in situ real-time measurements during oxidation. Change of the LSPR spectra throughout the oxidation follows a common pattern, observed for different temperatures, NP sizes and substrates. The well-defined initial Cu NP surface plasmon (SP) band red-shifts continuously with oxidation, while the extinction intensity initially increases to reach a maximum value at a characteristic oxidation time τ, after which the SP intensity continuously drops. The characteristic time τ is used as a scaling parameter for the kinetic analysis. Evolution of the SP wavelength and extinction intensity during oxidation at different temperatures follows the same kinetics when the oxidation time is normalized to τ, thus pointing to a general oxidation mechanism. The characteristic time τ is used to estimate the activation energy of the process, determined to be 144 ± 6 kJ mol−1, similar to previously reported values for high-temperature Cu thermal oxidation. The central role of the NKE in the solid-state oxidation process is revealed by electron microscopy, while formation of Cu2O as the major oxidation product is established by X-ray diffraction, XPS, and electrochemical measurements. The results indicate a transition of the oxidation mechanism from a Valensi–Carter (VC) to NKE mechanism with the degree of oxidation. To interpret the optical evolution during oxidation, Mie scattering solutions for metal core–oxide shell spherical particles are computed, considering formation of Kirkendall voids. The model calculations are in agreement with the experimental results, showing that the large red-shift of the LSPR band during oxidation is the result of Kirkendall voiding, thus establishing the major role of the NKE in determining the optical behavior of such systems.

Graphical abstract: Real-time plasmon spectroscopy study of the solid-state oxidation and Kirkendall void formation in copper nanoparticles

Back to tab navigation

Supplementary files

Publication details

The article was received on 14 Jun 2017, accepted on 09 Aug 2017 and first published on 10 Aug 2017


Article type: Paper
DOI: 10.1039/C7NR04256F
Citation: Nanoscale, 2017, Advance Article
  •   Request permissions

    Real-time plasmon spectroscopy study of the solid-state oxidation and Kirkendall void formation in copper nanoparticles

    M. D. Susman, Y. Feldman, T. A. Bendikov, A. Vaskevich and I. Rubinstein, Nanoscale, 2017, Advance Article , DOI: 10.1039/C7NR04256F

Search articles by author

Spotlight

Advertisements