Cobalt(II) tungstate

Cobalt(II) tungstate
Names
Other names
Cobalt tungstate
Identifiers
ECHA InfoCard 100.030.218 Edit this at Wikidata
EC Number
  • 233-254-8
Properties
CoWO4
Molar mass 306.77 g/mol
Appearance Greenish-blue to blue-black crystalline solid
Density 8.42 g/cm3
Melting point 1,280 °C (2,340 °F; 1,550 K)
Nearly insoluble in water
Structure
Monoclinic, wolframite type
P2/c, No. 13
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Cobalt(II) tungstate is an inorganic compound with the chemical formula CoWO4. It is a greenish-blue to blue-black crystalline solid and belongs to the wolframite family of transition-metal tungstates.

Structure and properties

Cobalt(II) tungstate crystallizes in the monoclinic crystal system with the wolframite-type structure, in space group P2/c (No. 13). Its structure contains distorted CoO6 and WO6 octahedra linked through shared edges and corners to form a three-dimensional framework.

CoWO4 is paramagnetic at room temperature and becomes antiferromagnetic at low temperature. Nanocrystalline CoWO4 has a reported Néel temperature of about 40 K, somewhat lower than bulk material because of reduced exchange coupling in nanoscale particles.

It is also a semiconductor. Reported optical band gaps are typically in the vicinity of 2.7–2.9 eV, and CoWO4 has been described as showing p-type electrical conductivity.

CoWO4 is nearly insoluble in water but dissolves in hot concentrated acids.

Occurrence

A material with the composition CoWO4 has been found in burning coal refuse and is known as krasnoselskite. Because it is of anthropogenic origin, it is not recognized by the International Mineralogical Association as a valid mineral species. It is classified structurally with the wolframite group.

Preparation

Cobalt(II) tungstate can be prepared by precipitation from aqueous solutions of cobalt(II) sulfate and sodium tungstate:

CoSO4 + Na2WO4 → CoWO4↓ + Na2SO4

Nanocrystalline CoWO4 can also be prepared hydrothermally. Hydrothermal syntheses without templates or surfactants have produced nanocrystals with sizes on the order of tens of nanometres.

Applications

Cobalt(II) tungstate has been investigated as a photocatalyst and electrocatalyst. In 2025, research examined CoWO4-based materials for oxygen evolution, oxygen reduction, nitrate reduction, photocatalytic hydrogen evolution, carbon dioxide reduction and degradation of organic pollutants.

It has also been used as a ceramic pigment and has been investigated as a catalyst and functional oxide material.

References

  1. 1 2 Deng, Jiwei; Chang, Liao; Wang, Ping; Zhang, Endi; Ma, Jianmin; Wang, Taihong (2012). "Preparation and magnetic properties of CoWO4 nanocrystals". Crystal Research and Technology. 47: 1004–. doi:10.1002/crat.201200130.
  2. ↑ "Krasnoselskite". Mindat.org. Retrieved 13 September 2026.
  3. ↑ "Cobalt tungstate for electrocatalytic and photocatalytic applications: Structure engineering, performance optimization, and future perspectives". International Journal of Hydrogen Energy. 2025.