KO2
Potassium superoxide · Potassium dioxide
Potassium superoxide is a yellowish solid that reacts readily with water and carbon dioxide. It is primarily used as a chemical oxygen source in specialized environments where air regeneration is required.
KO
Overview
Key Properties
Cross-validated computational properties for Potassium superoxide, aggregated across 3 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
0.15–0.50 eV
Range across DFT structures
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
0.000 eV/atom
Best (lowest) across sources
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
On hull (stable)
2 DFT sources
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
116
3 databases, 22 space groups
Crystallography
Reported Structures
Lowest-energy structures reported for KO2, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| Immm (No. 71) | orthorhombic | 0.00 | 0.0000 | -4.673 | 2.35 |
| P21/c (No. 14) | monoclinic | 0.18 | 0.0028 | -4.670 | 2.34 |
| I4/mmm (No. 139) | tetragonal | 0.00 | 0.0172 | -4.656 | 2.40 |
| P21/c (No. 14) | monoclinic | 0.00 | 0.0380 | -4.635 | 2.27 |
| P21/c (No. 14) | monoclinic | 0.00 | 0.0441 | -4.629 | 2.29 |
| C2/c (No. 15) | monoclinic | 0.15 | 0.0560 | -4.617 | 2.07 |
| Pa-3 (No. 205) | cubic | 0.00 | 0.0624 | -4.611 | 1.98 |
| P21/c (No. 14) | monoclinic | 0.01 | 0.0927 | -4.581 | 2.09 |
| C2/c (No. 15) | monoclinic | 0.50 | 0.2172 | -4.456 | 0.52 |
| P4/mmm (No. 123) | tetragonal | 0.00 | 1.0068 | -3.666 | 1.45 |
| P21/m (No. 11) | Monoclinic | — | — | — | 1.64 |
| P-1 (No. 2) | Triclinic | — | — | — | 0.91 |
Uses
Applications
Where Potassium superoxide is used.
Oxygen candlesSelf-contained breathing apparatusSubmarine air purificationSpacecraft life support systems
Reference
Frequently Asked Questions
Common questions about Potassium superoxide, answered from cross-validated data.
What is KO2?
Potassium superoxide is a yellowish solid that reacts readily with water and carbon dioxide. It is primarily used as a chemical oxygen source in specialized environments where air regeneration is required.
More questions
What is KO2 used for?
Potassium superoxide (KO2) is used in oxygen candles, self-contained breathing apparatus, submarine air purification, and spacecraft life support systems.
What is the band gap of KO2?
Potassium superoxide (KO2) has a DFT-computed band gap of 0.15–0.50 eV across 116 reported structures.
Is KO2 a metal, semiconductor, or insulator?
With a band gap up to 0.50 eV it is a semiconductor.
Is KO2 thermodynamically stable?
Yes — Potassium superoxide (KO2) sits on the convex hull (energy above hull 0 eV/atom), i.e. on hull (stable).
What is the crystal structure of KO2?
The lowest-energy reported polymorph of Potassium superoxide (KO2) is orthorhombic symmetry, space group Immm (No. 71).
What is the density of KO2?
The computed density of the ground-state structure of Potassium superoxide (KO2) is 2.35 g/cm³.
How many polymorphs of KO2 are known?
116 structures of KO2 are reported across 3 databases, spanning 22 distinct space groups.
What elements does KO2 contain?
Potassium superoxide (KO2) contains K and O (2 elements).
Where does the data for KO2 come from?
KO2 data is cross-referenced from materials_project, mpaloe.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- mpaloe — Data from mpaloe.
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