Role of Hexadecylamine in the Shape-Controlled Synthesis of Copper Nanocubes

Undergraduate #333
Discipline: Physics
Subcategory: Materials Science

Bria Andrews - Hampton University
Co-Author(s): Tonnam Balankura and Kristin Fichthorn, Department of Chemical Engineering, Penn State University, State College, PA

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The role of structure-directing agents (SDAs) in the shape-controlled synthesis of copper(Cu) nanocubes has not yet been thoroughly investigated. Cu nanostructures can potentially be used as materials for improved and inexpensive conductors in computer chips, high precision spectroscopy and imaging, catalysis, etc. The SDA examined was Hexadecylamine or HDA. HDA can act as a capping agent and has been used to manipulate surface energies and growth rates of different facets. It has also been thought to influence the surface energies or growth rates of facets by forming a self-assembled monolayer on the surface of nanostructures. This ultimately changes the shape and affects the properties of the nanocrystals, which alters the function and efficiency of the application [2]. Facets covered by capping agents like HDA have been suggested to have a slower growth rate. However, these hypotheses have not been completely supported. In this study, LAMMPS based molecular dynamics simulation was used to replicate the process of copper atom deposition to understand more about the shape control mechanism. Potential of mean force was calculated using umbrella sampling and umbrella integration, quantifying the influence of HDA on the growth rates of Cu (100) and Cu(111) facets.

Funder Acknowledgement(s): NSF, Pennsylvania State University.

Faculty Advisor: Kristen Fichthorn, kristen.fichthorn@psu.edu

Role: I contributed by using molecular dynamics to produce visuals. Molecular dynamics is a computer simulation method for studying physical movements of atoms and molecules. It gives views of the interactions, of molecules, evolution of the system, and the growth rate of the surfaces. I also used potential of mean force calculations to measure the influence of HDA on the growth rates of Cu(100) and Cu(111) facets.