Cottrell College Science Awards - 2015
Efficient Computational Screening and Chemical Understanding of Oxide Nanostructures for Energy Applications
We know of 118 different elements, of which 38 are “transition metals,” all of which are, to one degree or another, malleable and conduct electricity and heat. The “transition” term refers to the fact that their atoms have a valence shell (the electron “orbit,” or energy state), that allows them to readily connect with atoms of other elements.
Most commonly, transition metal atoms seem to connect to oxygen atoms, giving rise to many different varieties of “metal oxides.”
“Transition metal oxides exhibit remarkable diversity of composition, structure, and properties, and can often be manipulated at the atomic scale via strain, doping, layering, and the engineering of surfaces and interfaces,” notes Robert Berger, assistant professor of chemistry at Western Washington University.
In other words, transition metal oxides -- and their crystalline molecular structures -- present a wonderful opportunity for scientists looking to create new materials, especially compounds that may eventually prove useful for energy-related applications such as batteries, and devices that generate electricity directly from heat or sunlight.
Berger has received a Cottrell College Science Award from Research Corporation for Science Advancement to develop a new method to examine the behavior of electrons in very complex hybrid transition metal oxides.
The task is daunting.
“A small number of oxide building blocks can form infinite combinations by changing the thickness and orientation of the components,” Berger said. “In the same way that chains of a relatively small number of distinct amino acids constitute proteins with a staggering variety of functions, these metal oxide structures consisting of a few building blocks also have the potential to be highly tunable for desired functions.”
The trick is to more quickly and efficiently figure out what works and why.
Specifically, Berger and his students will attempt to tweak an existing computational method (extended Hückel) by combining it with relevant aspects of Density Functional Theory, a quantum mechanical modelling method, to screen oxide materials for desired electronic structures -- for example, to determine if they’re appropriate for solar panels.
If successful, their work will help guide synthetic chemists and materials scientists by providing fundamental understanding of the electronic structure of oxides, and by predicting concrete routes to tune them.