NaO2
sodium superoxide · sodium hyperoxide
Sodium superoxide is a stable, semiconducting inorganic compound consisting of sodium and oxygen that is widely studied for its role in chemical and electrochemical processes.
About sodium superoxide
Sodium superoxide is a semiconducting inorganic compound composed of sodium and oxygen. As a thermodynamically stable phase located on the convex hull, it represents a well-defined chemical state that has been extensively characterized across multiple structural databases.
Its significance lies in its role as a reactive oxygen species, which is critical in various chemical synthesis pathways and energy storage research. The compound's stability and electronic properties make it a subject of interest for those studying alkali metal oxides and their potential applications in advanced electrochemical systems.
Key Properties
Cross-validated computational properties for sodium superoxide, aggregated across 6 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.
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.
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.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of NaO2. Tight agreement means computed properties can be trusted without re-running calculations.
Agreement ScoreA normalized confidence score summarizing how closely independent DFT databases agree. Higher scores mean tighter cross-source agreement.
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
Reported Structures
Lowest-energy structures reported for NaO2, 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. |
|---|---|---|---|---|---|
| P21/c (No. 14) | monoclinic | 0.48 | 0.0000 | -4.654 | 2.34 |
| — | — | 0.00 | 0.0000 | -1.044 | — |
| Pnnm (No. 58) | orthorhombic | 0.00 | 0.0000 | -0.920 | — |
| Pnnm (No. 58) | orthorhombic | 0.00 | 0.0000 | -0.920 | — |
| Pnnm (No. 58) | orthorhombic | 0.00 | 0.0009 | -4.653 | 2.33 |
| — | — | 0.00 | 0.0019 | -1.042 | — |
| Pm (No. 6) | monoclinic | 0.00 | 0.0101 | -0.910 | — |
| Pa-3 (No. 205) | cubic | 0.00 | 0.0185 | -0.902 | — |
| Pbca (No. 61) | orthorhombic | 0.00 | 0.0204 | -4.633 | 2.48 |
| Pa-3 (No. 205) | cubic | 0.00 | 0.0207 | -4.633 | 2.17 |
| — | — | 0.00 | 0.0342 | -1.010 | — |
| P42/mnm (No. 136) | tetragonal | 0.00 | 0.0510 | -0.869 | — |
Applications
Where sodium superoxide is used.
Frequently Asked Questions
Common questions about sodium superoxide, answered from cross-validated data.
What is NaO2?
Sodium superoxide is a stable, semiconducting inorganic compound consisting of sodium and oxygen that is widely studied for its role in chemical and electrochemical processes.
What is NaO2 used for?
What is the band gap of NaO2?
Is NaO2 a metal, semiconductor, or insulator?
Is NaO2 thermodynamically stable?
What is the crystal structure of NaO2?
How many polymorphs of NaO2 are known?
What elements does NaO2 contain?
Where does the data for NaO2 come from?
How It Compares
As a primary alkali metal superoxide, this compound serves as a fundamental reference point for understanding the behavior of oxygen-rich ionic solids. It occupies a unique position in the landscape of sodium-oxygen chemistry, providing essential insights into the stability and electronic nature of superoxide-based materials.
Data sources & attribution
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- 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)
- 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.
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