KBH4

Potassium borohydride · Potassium tetrahydroborate

Potassium borohydride is a stable, insulating complex hydride primarily used as a selective reducing agent in chemical synthesis and as a model material for hydrogen storage research.

Crystal structure of KBH4 (cubic, Fm-3m (No. 225))
Ground-state structure · Materials Project
Overview

About Potassium borohydride

Potassium borohydride is a wide-band-gap insulating compound characterized by its high thermodynamic stability. As a member of the borohydride family, it serves as a robust platform for investigating hydrogen storage mechanisms and chemical reactivity. Its position on the convex hull underscores its structural reliability, making it a significant subject for materials research in energy storage.

The compound is frequently utilized in organic synthesis as a selective reducing agent. Its stable nature allows for controlled reactions, while its underlying chemistry provides insights into the broader class of complex hydrides used in hydrogen delivery systems.

At a glance

Key Properties

Cross-validated computational properties for Potassium borohydride, aggregated across 3 databases.

Band Gap

1.30–6.33 eV
Range across DFT structures · ground state: insulator

Energy Above Hull

0.000 eV/atom
Best (lowest) across sources

Stability

Stable
3 DFT sources

Structures

13
3 databases, 3 space groups
Validation

Cross-Source DFT Agreement

How well independent DFT databases agree on the thermodynamics of KBH4. Tight agreement means computed properties can be trusted without re-running calculations.

Agreement Score

1.00 / 1.00
Trust tier: high

Hull Spread

0.000 eV
EAH spread across sources

Sources Compared

3
jarvis, materials_project, oqmd

Space Group Consensus

All match
Crystallography

Reported Structures

Lowest-energy structures reported for KBH4, ranked by energy above hull.

Space GroupCrystal SystemBand Gap (eV)E above hull (eV/atom)E/atom (eV)Density (g/cm³)
——6.240.0000-0.399—
P42/nmc (No. 137)tetragonal6.100.0000-4.9851.25
P42/nmc (No. 137)tetragonal6.080.0000-0.447—
F-43m (No. 216)cubic6.220.0028-4.9821.24
——6.330.0048-0.394—
F-43m (No. 216)cubic6.060.0051-0.442—
Pnma (No. 62)orthorhombic1.300.3043-0.143—
——1.800.3147-0.084—
Pnma (No. 62)orthorhombic1.400.3156-4.6701.46
——0.001.97241.573—
F-43m (No. 216)cubic———1.18
F-43m (No. 216)cubic———1.17
Uses

Applications

Where Potassium borohydride is used.

Reducing agent in organic synthesisHydrogen storage researchChemical intermediate
Reference

Frequently Asked Questions

Common questions about Potassium borohydride, answered from cross-validated data.

What is KBH4?

Potassium borohydride is a stable, insulating complex hydride primarily used as a selective reducing agent in chemical synthesis and as a model material for hydrogen storage research.

More questions
What is KBH4 used for?
Potassium borohydride (KBH4) is used in reducing agent in organic synthesis, hydrogen storage research, and chemical intermediate.
What is the band gap of KBH4?
Potassium borohydride (KBH4) has a DFT-computed band gap of 1.30–6.33 eV across 13 reported structures. Standard DFT underestimates band gaps, so the measured gap is typically larger.
Is KBH4 a metal, semiconductor, or insulator?
DFT predicts a wide band gap of up to 6.33 eV (an insulator or wide-band-gap material).
Is KBH4 thermodynamically stable?
Yes — Potassium borohydride (KBH4) sits on the convex hull (energy above hull 0 eV/atom), i.e. stable.
What is the crystal structure of KBH4?
The reference structure of Potassium borohydride (KBH4) is cubic symmetry, space group Fm-3m (No. 225).
What is the density of KBH4?
The computed density of the ground-state structure of Potassium borohydride (KBH4) is 1.18 g/cm³.
How many polymorphs of KBH4 are known?
13 structures of KBH4 are reported across 3 databases, spanning 3 distinct space groups.
What elements does KBH4 contain?
Potassium borohydride (KBH4) contains B, H, and K (3 elements).
Where does the data for KBH4 come from?
KBH4 data is cross-referenced from oqmd, materials_project, jarvis, mpaloe, cod.
Comparison

How It Compares

Within the hydrogen storage hydrides class.

Compared to simple binary hydrides like LiH or MgH2, KBH4 offers a more complex structural framework that influences its hydrogen release kinetics. While compounds like AlH3 or BH3 are often noted for their higher gravimetric hydrogen density, KBH4 is distinguished by its superior thermodynamic stability, which simplifies handling and storage requirements relative to more reactive or volatile class members.

Explore

Related Compounds

Other Hydrogen Storage Hydrides in the database.

Data sources & attribution
  • oqmd — Data from the OQMD (oqmd.org). Cite: Saal et al., JOM 65, 1501 (2013); Kirklin et al., npj Comp. Mater. 1, 15010 (2015). (CC-BY-4.0)
  • materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
  • jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
  • mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
  • cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)

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