Title: Chemistry of hydrogen interactions with materials

Laboratory: Lawrence Livermore National Laboratory (LLNL) and Lawrence Berkeley National Laboratory (LBNL)

Category: Modeling/Simulation

Capability Experts: Brandon Wood (wood37@llnl.gov), ShinYoung Kang (kang10@llnl.gov), Keith Ray (ray30@llnl.gov), Tadashi Ogitsu (ogitsu1@llnl.gov), David Prendergast (dgprendergast@lbl.gov), Liwen Wan (lwan@lbl.gov)

Description: The development of specific strategies for optimizing solid-state hydrogen storage often relies on a comprehensive picture of the chemistry of hydrogen interaction with surfaces, interfaces, and bulk materials. HyMARC employs first-principles and kinetic modeling techniques to probe mechanisms, pathways, and energetics of these interactions. We offer the following techniques for sorbents and hydrides:

Accurate computation of weak binding of hydrogen molecules in sorbents: We employ first-principles density functional theory (DFT) with advanced functionals, along with beyond-DFT calculations, to computationally investigate binding energy curves for the interaction of H2 with framework and disordered sorbents. Effects of chemical functionalization or substitution on H2 binding beyond the van der Waals limit can be determined.

Chemical bond formation and breaking in hydrides: We combine DFT energetics, barrier calculations, and ab initio molecular dynamics to determine mechanisms and pathways for reaction chemistry in bulk metal hydrides, as well as at surfaces and interfaces. Predictions are validated by comparing spectroscopy data from experiments directly to simulated spectra. In addition to chemical insight, this approach can also help to identify unknown phases and compounds. Our capabilities for simulated spectroscopy currently include XAS/XES, XPS, NMR, Neutron methods, IR, and Raman.

Graphics

(a) Experimental and (b) simulated B K-edge TFY XAS data for MgB2 compared to MgB12H12, Mg(BH4)2, and B2O3. [1]

References

[1] K.G. Ray, L.E. Klebanoff, J.R.I. Lee, V. Stavila, T.W. Heo, P. Shea, A.A. Baker, S. Kang, M. Bagge-Hansen, Y.-S. Liu, J.L. White and B.C. Wood, “Elucidating the mechanisms of MgB2 initial hydrogenation via a combined experiment-theory study,” Phys. Chem. Chem. Phys. 19, 22646 (2017).

[2] L.F. Wan, Y.-S. Liu, E.S. Cho, J.D. Forster, S. Jeong, H.-T. Wang, J.J. Urban, J. Guo, and D. Prendergast, “Atomically thin interfacial suboxide key to hydrogen storage performance enhancements of magnesium nanoparticles encapsulated in reduced graphene oxide,” Nano Lett. 17, 5540 (2017).