Ni2P2O7
nickel pyrophosphate · nickel(II) pyrophosphate
Nickel pyrophosphate is a stable, insulating phosphate-based oxide used primarily in the study of oxygen-evolution catalysis.
About nickel pyrophosphate
Nickel pyrophosphate is a thermodynamically stable inorganic compound characterized by its insulating electronic nature. As a member of the oxide oxygen-evolution catalyst family, it provides a robust structural framework that is highly relevant for electrochemical energy conversion research. Its presence across multiple structural databases highlights its significance as a well-defined material phase. The compound is primarily investigated for its catalytic potential in electrochemical systems where oxygen evolution is a critical process. Its stability makes it a reliable candidate for studies involving long-term performance in catalytic environments.
Key Properties
Cross-validated computational properties for nickel pyrophosphate, 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 Ni2P2O7. 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 Ni2P2O7, 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. |
|---|---|---|---|---|---|
| — | — | 4.08 | 0.0000 | -2.154 | — |
| P21/c (No. 14) | monoclinic | 1.54 | 0.0000 | -7.413 | 4.28 |
| P21/c (No. 14) | monoclinic | 0.81 | 0.0000 | -1.727 | — |
| P21/c (No. 14) | monoclinic | 3.60 | 0.0023 | -7.410 | 4.14 |
| — | — | 4.07 | 0.0055 | -2.149 | — |
| — | — | 4.00 | 0.0065 | -2.148 | — |
| P21/c (No. 14) | monoclinic | 0.89 | 0.0072 | -1.720 | — |
| C2/m (No. 12) | monoclinic | 1.12 | 0.0093 | -7.403 | 4.24 |
| C2/m (No. 12) | monoclinic | 0.74 | 0.0188 | -1.708 | — |
| P21/c (No. 14) | monoclinic | — | — | — | 4.22 |
| C2/m (No. 12) | monoclinic | — | — | — | 4.37 |
| P21/c (No. 14) | monoclinic | — | — | — | 4.41 |
Applications
Where nickel pyrophosphate is used.
Frequently Asked Questions
Common questions about nickel pyrophosphate, answered from cross-validated data.
What is Ni2P2O7?
Nickel pyrophosphate is a stable, insulating phosphate-based oxide used primarily in the study of oxygen-evolution catalysis.
What is Ni2P2O7 used for?
What is the band gap of Ni2P2O7?
Is Ni2P2O7 a metal, semiconductor, or insulator?
Is Ni2P2O7 thermodynamically stable?
What is the crystal structure of Ni2P2O7?
What is the density of Ni2P2O7?
How many polymorphs of Ni2P2O7 are known?
What elements does Ni2P2O7 contain?
Where does the data for Ni2P2O7 come from?
How It Compares
Within the oxide oxygen-evolution catalysts class.
Unlike the highly conductive perovskite-structured oxides such as LaNiO3 or the layered lithium-based intercalation materials like LiCoO2 and LiNiO2, nickel pyrophosphate functions as a wide-gap insulator. While many members of this class are metallic or semi-conductive, this pyrophosphate offers a distinct chemical environment that differentiates its catalytic mechanism from the transition metal oxides like NiO or the complex spinels like LiMn2O4.
Related Compounds
Other Oxide Oxygen-Evolution Catalysts 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)
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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