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12 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on NaBH4 by Materials Project

NaBH4 crystallizes in the orthorhombic Pnma space group. The structure is two-dimensional and consists of two NaBH4 sheets oriented in the (0, 0, 1) direction. Na1+ is bonded in a 7-coordinate geometry to seven H+0.50+ atoms. There are a spread of Na–H bond distances ranging from 2.19–2.57 Å. B3- is bonded in a tetrahedral geometry to four H+0.50+ atoms. There are a spread of B–H bond distances ranging from 1.22–1.24 Å. There are three inequivalent H+0.50+ sites. In the first H+0.50+ site, H+0.50+ is bonded in a single-bond geometry to two equivalent Na1+ and one B3- atom. In the second H+0.50+ site, H+0.50+ is bonded in a distorted single-bond geometry to one Na1+ and one B3- atom. In the third H+0.50+ site, H+0.50+ is bonded in a 1-coordinate geometry to two equivalent Na1+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaBH4 by Materials Project

NaBH4 crystallizes in the tetragonal P-42_1c space group. The structure is three-dimensional. Na1+ is bonded in a 12-coordinate geometry to twelve equivalent H+0.50+ atoms. There are a spread of Na–H bond distances ranging from 2.46–2.59 Å. B3- is bonded in a tetrahedral geometry to four equivalent H+0.50+ atoms. All B–H bond lengths are 1.23 Å. H+0.50+ is bonded in a distorted single-bond geometry to three equivalent Na1+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaBH4 by Materials Project

NaBH4 crystallizes in the cubic F-43m space group. The structure is three-dimensional. Na1+ is bonded in a 12-coordinate geometry to twelve equivalent H+0.50+ atoms. All Na–H bond lengths are 2.53 Å. B3- is bonded in a tetrahedral geometry to four equivalent H+0.50+ atoms. All B–H bond lengths are 1.23 Å. H+0.50+ is bonded in a single-bond geometry to three equivalent Na1+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaBH4 by Materials Project

NaBH4 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven H+0.50+ atoms. There are a spread of Na–H bond distances ranging from 2.26–2.49 Å. In the second Na1+ site, Na1+ is bonded in a 9-coordinate geometry to nine H+0.50+ atoms. There are a spread of Na–H bond distances ranging from 2.28–2.54 Å. There are two inequivalent B3- sites. In the first B3- site, B3- is bonded in a tetrahedral geometry to four H+0.50+ atoms. There is one shorter (1.22 Å) and three longer (1.23 Å) B–H bond length. In the second B3- site, B3- is bonded in a tetrahedral geometry to four H+0.50+ atoms. All B–H bond lengths are 1.23 Å. There are six inequivalent H+0.50+ sites. In the first H+0.50+ site, H+0.50+ is bonded in a distorted single-bond geometry to two Na1+ and one B3- atom. In the second H+0.50+ site, H+0.50+ is bonded in a distorted single-bond geometry to two Na1+ and one B3- atom. In the third H+0.50+ site, H+0.50+ is bonded in a distorted single-bond geometry to two equivalent Na1+ and one B3- atom. In the fourth H+0.50+ site, H+0.50+ is bonded in a distorted single-bond geometry to two Na1+ and one B3- atom. In the fifth H+0.50+ site, H+0.50+ is bonded in a distorted single-bond geometry to two equivalent Na1+ and one B3- atom. In the sixth H+0.50+ site, H+0.50+ is bonded in a distorted single-bond geometry to two equivalent Na1+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaBH4 by Materials Project

NaBH4 crystallizes in the tetragonal P-42_1c space group. The structure is three-dimensional. Na1+ is bonded in a 8-coordinate geometry to eight equivalent H+0.50+ atoms. There are four shorter (2.42 Å) and four longer (2.45 Å) Na–H bond lengths. B3- is bonded in a tetrahedral geometry to four equivalent H+0.50+ atoms. All B–H bond lengths are 1.23 Å. H+0.50+ is bonded in a distorted single-bond geometry to two equivalent Na1+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaBH4 by Materials Project

NaBH4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Na1+ is bonded in a 12-coordinate geometry to twelve H+0.50+ atoms. There are a spread of Na–H bond distances ranging from 2.39–2.67 Å. B3- is bonded in a tetrahedral geometry to four H+0.50+ atoms. There is two shorter (1.22 Å) and two longer (1.23 Å) B–H bond length. There are three inequivalent H+0.50+ sites. In the first H+0.50+ site, H+0.50+ is bonded in a single-bond geometry to three equivalent Na1+ and one B3- atom. In the second H+0.50+ site, H+0.50+ is bonded in a distorted single-bond geometry to three equivalent Na1+ and one B3- atom. In the third H+0.50+ site, H+0.50+ is bonded in a distorted single-bond geometry to three equivalent Na1+ and one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Synthesis of Cp* Terphenylamido U(III) Iodide Complexes with a Substitutable Iodide Position to Generate Terminal U(III)–(κ 3 -BH 4 ) Complexes

Reaction of Cp*UI 2 (THF) 3 (Cp* = pentamethylcyclopentadienide; THF = tetrahydrofuran) with Na R3 TerNH ( R3 Ter = 2,6(2,4,6-R 3 C 6 H 2 ) 2 C 6 H 3 ; R = Me, Et, iPr) gave the U(III) monoiodide complexes Cp*( R3 TerNH)UI (R = Me, 1-Me; R = Et, 2-Et; R = iPr, 3-iPr). These complexes contain a functionalizable iodide position which reacts favorably with NaBH4 to give the κ 3 -borohydride complexes Cp*( R3 TerNH)U(H 3 BH) (R = Me, 4-Me; R = Et, 5-Et; R = iPr, 6-iPr). All compounds were experimentally characterized by SC-XRD, 1 H and 11 B NMR spectroscopy as well as UV–vis–NIR and FTIR analyses. DFT calculations corroborate the experimental findings, confirming the 5f 3 U(III) configuration across the entire series and revealing an increased U 5f orbital contribution in the borohydride derivatives. All compounds exhibit small but non-negligible U(III)–(η 6 -arene) δ-back-bonding interactions arising from the unpaired 5f electrons. Calculated steric parameters show progressively greater shielding of the U(III) center with increasing bulk of the terphenyl substituents from Me to iPr.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2024

Nanoscopic Imaging of Self-Propelled Ultrasmall Catalytic Nanomotors

Ultrasmall nanomotors (<100 nm) are highly desirable nanomachines for their size-specific advantages over their larger counterparts in applications spanning nanomedicine, directed assembly, active sensing, and environmental remediation. While there are extensive studies on motors larger than 100 nm, the design and understanding of ultrasmall nanomotors have been scant due to the lack of high-resolution imaging of their propelled motions with orientation and shape details resolved. Here, we report the imaging of the propelled motions of catalytically powered ultrasmall nanomotors─hundreds of them─at the nanometer resolution using liquid-phase transmission electron microscopy. These nanomotors are Pt nanoparticles of asymmetric shapes (“tadpoles” and “boomerangs”), which are colloidally synthesized and observed to be fueled by the catalyzed decomposition of NaBH4 in solution. Statistical analysis of the orientation and position trajectories of fueled and unfueled motors, coupled with finite element simulation, reveals that the shape asymmetry alone is sufficient to induce local chemical concentration gradient and self-diffusiophoresis to act against random Brownian motion. Our work elucidates the colloidal design and fundamental forces involved in the motions of ultrasmall nanomotors, which hold promise as active nanomachines to perform tasks in confined environments such as drug delivery and chemical sensing.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Synthesis and Flash Sintering of (Hf1-xZrx)B2 Solid Solution Fine Powders

Fine powders of (Hf1-xZrx)B2 solid solution were synthesized by two methods. In the first one, solution-based processing of HfCl4, ZrCl4, sucrose and H3BO3 was carried out followed by heat treatment (e.g., at 1500 °C for 1 h) in Argon to achieve the carbothermal reduction (CTR) reaction to form the boride solid solution. In the second one, called boron hydride reduction (BHR) method, HfCl4, ZrCl4 and NaBH4 were directly mixed in a glove box followed by heat treatment in Argon at elevated temperatures from 700 to 1500 °C. In addition, the powders synthesized via both methods were flash sintered without sample preheating in a homemade setup. The synthesized powders as well as the flash sintered bulk ceramics were characterized using different techniques including XRD, SEM, EDS, TEM, TGA-DSC, and Vickers hardness test to reveal the inter-relationships between starting materials composition, processing conditions, and the resulting materials microstructure and physical/chemical properties.

Belisario, Jose↗
DOE OSTI2022

Ru Single Atoms on One-Dimensional CF@g-C 3 N 4 Hierarchy as Highly Stable Catalysts for Aqueous Levulinic Acid Hydrogenation

Herein, we report a stable catalyst with Ru single atoms anchored on a one-dimensional carbon fiber@graphitic carbon nitride hierarchy, by assembling wet wipes composed of fiber-derived carbon fiber (CF), melamine-derived graphitic carbon nitride (g-C3N4) and RuCl3 before NaBH4 reduction. The atomically dispersed Ru species (3.0 wt%) are tightly attached via N-coordination provided by exterior g-C3N4 nanosheets, and further stabilized by the interior mesoporous CF. The obtained CF@g-C3N4–Ru SAs catalyst can be cycled six times without notable leaching of Ru or loss of GVL yield in the acidic media. This catalyst is more stable than Ru nanoparticles supported on CF@g-C3N4, as well as Ru single atoms anchored on CF and g-C3N4, and proves to be one of the most efficient metal catalysts for aqueous LA hydrogenation to γ-valerolactone (GVL). The isolated Ru atoms by strong N-coordination, and their enhanced electron/mass transfer afforded by the one-dimensional hierarchy, can be responsible for the excellent durability of CF@g-C3N4–Ru SAs under harsh reaction conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Using Additives to Control the Decomposition Temperature of Sodium Borohydride

Hydrogen (H 2 ) shows great promise as zero-carbon emission fuel, but there are several challenges to overcome in regards to storage and transportation to make it a more universal energy solution. Gaseous hydrogen requires high pressures and large volume tanks while storage of liquid hydrogen requires cryogenic temperatures; neither option is ideal due to cost and the hazards involved. Storage in the solid state presents an attractive alternative, and can meet the U.S. Department of Energy (DOE) constraints to find materials containing > 7 % H 2 (gravimetric weight) with a maximum H 2 release under 125 °C. While there are many candidate hydrogen storage materials, the vast majority are metal hydrides. Of the hydrides, this review focuses solely on sodium borohydride (NaBH 4 ), which is often not covered in other hydride reviews. However, as it contains 10.6% (by weight) H 2 that can release at 133 ± 3 JK -1 mol -1 , this inexpensive material has received renewed attention. NaBH 4 should decompose to H 2 (g), Na(s), and B(s), and could be recycled into its original form. Unfortunately, metal to ligand charge transfer in NaBH 4 induces high thermodynamic stability, creating a high decomposition temperature of 530 °C. In an effort make H 2 more accessible at lower temperatures, researchers have incorporated additives to destabilize the structure. This review highlights metal additives that have successfully reduced the decomposition temperature of NaBH 4 , with temperatures ranging from 522 °C (titanium (IV) fluoride) to 379 °C (niobium (V) fluoride). We describe synthetic methods employed, chemical pathways taken, and the challenges of boron derivative formation on H 2 cycling. Though no trends can be found across all additives, it is our hope that compiling the data here will enable researchers to gain a better understanding of the additives’ influence and to determine how a new system might be designed to make NaBH 4 a more viable H 2 fuel source.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗