NiP2O7
nickel pyrophosphate · nickel(II) pyrophosphate
NiP2O7 is a semiconducting nickel-based pyrophosphate studied as a potential catalyst for oxygen-evolution reactions in electrochemical systems.
About nickel pyrophosphate
Nickel pyrophosphate is a semiconducting oxide that functions within the broader family of oxygen-evolution catalysts. Its structural framework, characterized by pyrophosphate groups coordinated with nickel centers, makes it a subject of interest for electrochemical water-splitting applications. Despite its complex structural chemistry, it remains a notable example of transition metal phosphates being evaluated for their catalytic activity. Because this compound sits above the thermodynamic hull, it is considered metastable, which influences its synthesis pathways and long-term performance in catalytic environments. This metastability is a key factor in research aimed at stabilizing the material for practical energy conversion systems.
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 NiP2O7. 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 NiP2O7, 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. |
|---|---|---|---|---|---|
| C2 (No. 5) | monoclinic | 0.18 | 0.0201 | -1.656 | — |
| C2/c (No. 15) | monoclinic | 0.53 | 0.1448 | -7.122 | 2.93 |
| P21/c (No. 14) | monoclinic | 0.09 | 0.1527 | -7.114 | 2.88 |
| P21/c (No. 14) | monoclinic | 0.00 | 0.1570 | -7.110 | 2.94 |
| P1 (No. 1) | triclinic | 0.00 | 0.1627 | -7.104 | 2.69 |
| P21/c (No. 14) | monoclinic | 0.06 | 0.1674 | -7.100 | 2.99 |
| — | — | 0.00 | 0.1710 | -1.886 | — |
| C2 (No. 5) | monoclinic | 0.16 | 0.1798 | -7.087 | 3.12 |
| — | — | 0.00 | 0.2301 | -1.827 | — |
| P-1 (No. 2) | triclinic | 0.00 | 0.2318 | -7.035 | 3.06 |
| P21 (No. 4) | monoclinic | 0.01 | 0.2720 | -6.995 | 2.84 |
| P-1 (No. 2) | triclinic | 0.00 | 0.3033 | -6.964 | 2.86 |
Applications
Where nickel pyrophosphate is used.
Frequently Asked Questions
Common questions about nickel pyrophosphate, answered from cross-validated data.
What is NiP2O7?
NiP2O7 is a semiconducting nickel-based pyrophosphate studied as a potential catalyst for oxygen-evolution reactions in electrochemical systems.
What is NiP2O7 used for?
What is the band gap of NiP2O7?
Is NiP2O7 a metal, semiconductor, or insulator?
Is NiP2O7 thermodynamically stable?
What is the crystal structure of NiP2O7?
What is the density of NiP2O7?
How many polymorphs of NiP2O7 are known?
What elements does NiP2O7 contain?
Where does the data for NiP2O7 come from?
How It Compares
Within the oxide oxygen-evolution catalysts class.
Unlike the highly stable and widely utilized binary oxide NiO or the layered lithium-intercalation compounds like LiNiO2 and LiCoO2, NiP2O7 represents a more specialized phosphate-based approach to catalysis. While perovskite-structured oxides such as LaNiO3 and LaMnO3 are frequently studied for their robust electronic conductivity and surface activity, NiP2O7 offers a distinct chemical environment where the phosphate polyanions modify the electronic landscape of the nickel sites, potentially offering different pathways for oxygen evolution compared to conventional transition metal oxides.
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)
- 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)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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