Single Copper Nanoparticle Oxidation
Licentiatavhandling, 2019

Cu nanoparticles are commonly used in microelectronic devices and as catalysts in, for example, methanol synthesis and methanol steam reforming reactions. However, Cu nanoparticles are prone to oxidation. During the oxidation process so-called Kirkendall voids often form due to different diffusion rates of oxygen and copper ions through the growing oxide. The growing void entirely transforms the nanoparticle structure, leading to fatal failure of microelectronic devices or to radically different catalytic properties. It is therefore of fundamental interest to gain deeper insight into the oxidation mechanism of nanoparticles to, for instance, understand under which conditions Kirkendall voids form. For this purpose, it is ideal to study the oxidation of Cu nanoparticles at the single particle level under close-to real application conditions since there is evidence that the grain structure significantly affects the oxidation mechanism and may accelerate or suppress the Kirkendall void formation.
 
Since only a handful of single particle studies concerning the oxidation of Cu nanoparticles exist to date, all but one by means of transmission electron microscopy (TEM), in this thesis I have developed an in situexperimental method for studying the oxidation of single Cu nanoparticles. It combines the structural information from TEM imaging with a non-invasive optical dark-field scattering spectroscopy method – plasmonic nanospectroscopy – that enables the tracking of oxidation kinetics in real time. In this way, I can minimize exposure of the particles to the electron beam in the TEM, and thus minimize the risk for beam-induced structural and chemical changes to the particles during the experiments.
 
Using this platform in combination with finite-difference time-domain electrodynamics simulations of models representing different stages during the oxidation, I was able to systematically analyze the single particle optical response measured in the experiments and thus shed light on the oxidation of the single Cu nanoparticles from a mechanistic perspective. As the first key result, we found a distinct evolution of the single particle dark-field scattering spectra of single Cu nanoparticles indicative of Kirkendall void formation. As the second key result, we identified a clear dependence of the induction time to the onset of Kirkendall void formation on the grain structure of the single nanoparticles, where an abundance of high-angle grain boundaries favors the coalescence of vacancies into one large void.

dark-field scattering spectroscopy

single particle

plasmonic nanospectroscopy

plasmonic sensing

transmission electron microscopy

oxidation

nanoscale Kirkendall effect

PJ
Opponent: Maria Messing, Lunds Universitet, Sverige

Författare

Sara Nilsson

Chalmers, Fysik, Kemisk fysik

Nilsson, S., Albinsson, D., Antosiewicz, T., Friztsche, J., Langhammer, C., In situ Plasmonic Nanospectroscopy of Single Cu Nanoparticle Oxidation and Kirkendall Void Formation

Nilsson, S., Albinsson, D., Bastos da Silva Fanta, A., Friztsche, J., Langhammer, C., Grain Boundary Mediated Oxidation of Single Cu Nanoparticles

Single Particle Catalysis in Nanoreactors (SPCN)

Knut och Alice Wallenbergs Stiftelse, 2016-01-01 -- 2020-12-31.

Drivkrafter

Hållbar utveckling

Styrkeområden

Nanovetenskap och nanoteknik (2010-2017)

Materialvetenskap

Ämneskategorier

Fysik

Materialkemi

Nanoteknik

Fundament

Grundläggande vetenskaper

Infrastruktur

Chalmers materialanalyslaboratorium

Nanotekniklaboratoriet

Utgivare

Chalmers tekniska högskola

PJ

Opponent: Maria Messing, Lunds Universitet, Sverige

Mer information

Senast uppdaterat

2019-05-10