Physics Colloquium: Exploring the Surface Dynamics of Bimetallic Nanomaterials
Physics Colloquium
Exploring the Surface Dynamics of Bimetallic Nanomaterials: From Overlayers to Nanoparticles
Dr. Obioma Uche
Assistant Professor
Chemical Engineering, RIT
Abstract:
Surface dynamics plays a key role in processes which are relevant for a variety of applications such as thin films, functionalized nanomaterials, and heterogeneous catalysis. Although microscopy techniques are useful for investigating the phenomenon, there are limitations regarding their applicability. For example, these surface analysis tools are unable to resolve the reduced time scales at which intriguing behavior may occur. In this presentation, we will employ molecular simulation methods to provide insights on the dynamics of two sets of bimetallic systems. Firstly, we investigate the diffusion of two-dimensional, hexagonal silver islands on copper and nickel substrates below room temperature. Our results indicate that certain-sized islands diffuse orders of magnitude faster than other islands and even single atoms under similar conditions. An analysis of several low-energy pathways reveals two governing processes: a rapid, glide-centric process and a slower, vacancy-assisted one. The relative magnitude of the energies required to nucleate a vacancy appears to play a role in determining the size-selective diffusion of these islands. Secondly, we study the transformation mechanics between cuboctahedral and icosahedral geometries of gold-silver bimetallic nanoparticles. Our findings reveal that transformation between the above geometries occurs via a martensitic, symmetric mechanism for the investigated sizes. The associated transformation barriers are observed to be strongly dependent on both size and morphology. In addition, the barriers are shown to be correlated with the silver content of the bimetallic nanoparticles.
Speaker Bio:
Dr. Obioma Uche is currently an Assistant Professor of Chemical Engineering at the Rochester Institute of Technology. She earned her Ph.D. degree in Chemical Engineering from Princeton University. Her research interests focus on the application of molecular simulation techniques to understand the interfacial behavior of solid, catalytic surfaces and evaluate the structure-function relationships of heterogeneous catalysts. While at RIT, her research program has been supported by grants from the Army Research Laboratory and American Association of University Women.
Intended Audience:
Anyone with interest in the topic. All are Welcome.
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Event Snapshot
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Open to the Public
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