NiHO2
Nickel oxyhydroxide · NiOOH
NiHO2 is a semiconducting nickel oxyhydroxide compound that acts as a potent catalyst for oxygen-evolution reactions in electrochemical systems.
About Nickel oxyhydroxide
NiHO2 is a semiconducting nickel oxyhydroxide that serves as a critical material in the field of oxygen-evolution catalysts. Its unique electronic structure facilitates the charge transfer processes necessary for efficient electrochemical water splitting and energy conversion technologies.
As a metastable compound, it plays a vital role in the dynamic surface chemistry of nickel-based electrodes. Its ability to undergo structural transitions under operational conditions makes it a subject of significant interest for researchers aiming to improve the longevity and efficiency of next-generation catalytic systems.
Key Properties
Cross-validated computational properties for Nickel oxyhydroxide, 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.
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 NiHO2. 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 NiHO2, 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. |
|---|---|---|---|---|---|
| Cm (No. 8) | monoclinic | 0.00 | 0.0000 | -0.918 | — |
| — | — | 2.22 | 0.0245 | -1.066 | — |
| Cm (No. 8) | monoclinic | 0.09 | 0.0299 | -5.829 | 4.53 |
| P3m1 (No. 156) | trigonal | 0.00 | 0.0520 | -0.866 | — |
| — | — | 0.00 | 0.0880 | -1.002 | — |
| P3m1 (No. 156) | trigonal | 0.00 | 0.0884 | -5.770 | 4.33 |
| — | — | 0.00 | 0.0885 | -1.002 | — |
| — | — | 0.00 | 0.0885 | -1.002 | — |
| — | — | 0.26 | 0.0913 | -0.999 | — |
| — | — | 0.58 | 0.0956 | -0.995 | — |
| — | — | 0.00 | 0.0976 | -0.993 | — |
| — | — | 0.00 | 0.1055 | -0.985 | — |
Applications
Where Nickel oxyhydroxide is used.
Frequently Asked Questions
Common questions about Nickel oxyhydroxide, answered from cross-validated data.
What is NiHO2?
NiHO2 is a semiconducting nickel oxyhydroxide compound that acts as a potent catalyst for oxygen-evolution reactions in electrochemical systems.
What is NiHO2 used for?
What is the band gap of NiHO2?
Is NiHO2 a metal, semiconductor, or insulator?
Is NiHO2 thermodynamically stable?
What is the crystal structure of NiHO2?
What is the density of NiHO2?
How many polymorphs of NiHO2 are known?
What elements does NiHO2 contain?
Where does the data for NiHO2 come from?
How It Compares
Within the oxide oxygen-evolution catalysts class.
Within the diverse family of oxide catalysts, NiHO2 functions as a highly active surface phase compared to more thermodynamically stable oxides like NiO. While complex mixed-metal oxides such as LiNiO2 or LaNiO3 are often utilized for their bulk electronic properties, NiHO2 is frequently the active species formed during the electrochemical cycling of these materials, highlighting its importance as a transient but essential catalytic intermediate.
Related Compounds
Other Oxide Oxygen-Evolution Catalysts in the database.
Data sources & attribution
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- 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)
- 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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