A
Mechanistic Analysis of Phase Evolution and Hydrogen
Storage Behavior in Nanocrystalline Mg(BH<sub>4</sub>)<sub>2</sub> within Reduced Graphene Oxide
Sohee Jeong
Tae Wook Heo
Julia Oktawiec
Rongpei Shi
ShinYoung Kang
James L. White
Andreas Schneemann
Edmond W. Zaia
Liwen F. Wan
Keith G. Ray
Yi-Sheng Liu
Vitalie Stavila
Jinghua Guo
Jeffrey R. Long
Brandon C. Wood
Jeffrey J. Urban
10.1021/acsnano.9b07454.s001
https://acs.figshare.com/articles/journal_contribution/A_Mechanistic_Analysis_of_Phase_Evolution_and_Hydrogen_Storage_Behavior_in_Nanocrystalline_Mg_BH_sub_4_sub_sub_2_sub_within_Reduced_Graphene_Oxide/11638212
Magnesium
borohydride (Mg(BH<sub>4</sub>)<sub>2</sub>, abbreviated
here MBH) has received tremendous attention as a promising onboard
hydrogen storage medium due to its excellent gravimetric and volumetric
hydrogen storage capacities. While the polymorphs of MBHalpha
(α), beta (β), and gamma (γ)have distinct
properties, their synthetic homogeneity can be difficult to control,
mainly due to their structural complexity and similar thermodynamic
properties. Here, we describe an effective approach for obtaining
pure polymorphic phases of MBH nanomaterials within a reduced graphene
oxide support (abbreviated MBHg) under mild conditions (60–190
°C under mild vacuum, 2 Torr), starting from two distinct samples
initially dried under Ar and vacuum. Specifically, we selectively
synthesize the thermodynamically stable α phase and metastable
β phase from the γ-phase within the temperature range
of 150–180 °C. The relevant underlying phase evolution
mechanism is elucidated by theoretical thermodynamics and kinetic
nucleation modeling. The resulting MBHg composites exhibit structural
stability, resistance to oxidation, and partially reversible formation
of diverse [BH<sub>4</sub>]<sup>−</sup> species during de-
and rehydrogenation processes, rendering them intriguing candidates
for further optimization toward hydrogen storage applications.
2020-01-17 16:37:41
nucleation modeling
α phase
phase evolution mechanism
polymorphic phases
γ- phase
hydrogen storage capacities
onboard hydrogen storage medium
Mg
Mechanistic Analysis
temperature range
MBH nanomaterials
BH 4
Phase Evolution
graphene oxide support
Reduced Graphene Oxide Magnesium borohydride
metastable β phase
rehydrogenation processes
MBHg composites exhibit
Hydrogen Storage Behavior
hydrogen storage applications