Hydrogen is an excellent energy carrier with potential uses in next-generation transportation, energy storage, and diverse chemical processes, but efficient and cost-effective storage of hydrogen remains challenging. Although stakeholders in developing a global hydrogen infrastructure are currently focused on high-pressure tanks, solid-state materials have unique potential to deliver hydrogen with much lower storage pressures and at far higher densities. Among the available options, complex metal hydrides promise high storage capacities but suffer from thermodynamic and kinetic limitations that are often poorly understood.<br/><br/>Computational studies of hydrogen storage materials have mostly have focused on thermodynamic predictions of reaction enthalpies. Far fewer studies have tackled the relevant kinetic phenomena, including how hydrogen interacts with material surfaces, and how initial chemical reactions relate to the formation of new phases. This talk will address how multiscale computational methods have been applied within the U.S. Department of Energy Hydrogen Storage Materials—Advanced Research Consortium (HyMARC) to understand fundamental mechanisms governing the interaction of hydrogen with model complex hydrides.<br/><br/>Focusing on recent examples from our work on the Mg-B-H and Na-Al-H complex metal hydride systems, I will show how spectroscopy and computational modeling can be integrated to understand the initial reactions of hydrogen molecules with surfaces and to elucidate how bonds are broken and formed. Particular emphasis will be placed on the role of defects, interfaces, and oxide chemical impurities, which we find are critical to understanding the hydrogenation chemistry. I will also discuss how computational investigations at multiple scales can help to identify how surface and interface reactions relate to key pathways and kinetic limitations associated with the nucleation of product phases.

Computational studies of kinetic mechanisms governing hydrogen interactions with complex hydrides

255th National Meeting (2018)

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