WFU Physics Colloquium

TITLE: Improving Existing and Discovering New Hydrogen Storage Materials Using Computational Materials Modeling

SPEAKER: David Harrison

TIME: Monday April 17, 2017 at 12:30 PM

PLACE: Room 204 ZSR Library

Alternative energy is one of the most active research areas in science currently. Lessening our dependence on fossil fuels has economic, environmental, and political benefits. With almost one-third of US energy going into transportation, a large piece of the puzzle is developing an alternative energy carrier to petroleum. Hydrogen is very attractive in the long term because it is abundant, potentially renewable, all countries have access to it, and it burns cleanly (no CO₂ production) with oxygen to produce a large amount of energy (120 kJ/g). Unfortunately, there are still plenty of basic science and engineering hurdles that need to be overcome for hydrogen to be viable. Foremost among these is storing hydrogen in a sufficiently dense medium such that it can be used for automotive applications.

In this work, computational modeling was used to investigate several techniques for improving hydrogen storage within borohydride materials and an entirely new class of hydrogen storage material that we have predicted. More specifically, borohydrides are promising hydrogen storage materials with two primary flaws: 1) the temperature at which they release hydrogen is often too high to be practical and 2) they also release diborane, which is poisonous to the fuel cell. I will first discuss how to lower the temperature of hydrogen release within borohydrides by alloying two borohydrides which have different metal cations, making significant progress towards solving the first issue. I will then discuss how to suppress diborane production within borohydrides by alloying different borohydrides and address the question which combinations and concentrations of borohydride alloys can be expected to produce diborane or not. Finally, I will discuss a new class of hydrogen storage materials we have predicted—known as H4-alkanes—where 4-H₂ molecules are physisorbed to each carbon atom on an alkane chain, exhibiting an exceptionally high hydrogen storage density.