Nickel oxide (Nickel(II) oxide), with the chemical formula NiO, is an important inorganic compound, Appearance: Typically an olive-green crystalline powder, although it can also be described as black to gray powder or green powder. CAS Registry Number: 1313-99-1.
Appearance: Typically an olive-green crystalline powder, although it can also be described as black to gray powder or green powder.
Chemical Formula: NiO
Molecular Weight: 74.693
CAS Registry Number: 1313-99-1
EINECS Number: 215-215-7
Melting Point: 1960°C (some sources indicate 1980±20°C)
Density: 6.67 g/cm³
Solubility: Insoluble in water and alkaline solutions, but soluble in acids and ammonia water.
Physical and Chemical Properties
Crystal Structure: Cubic system, similar to the rock salt structure of sodium chloride.
Electrical Conductivity: An insulator due to the entanglement of its internal structure, preventing the flow of charge carriers.
Physical Property Variations: As the preparation temperature changes, its density and electrical resistance increase, while solubility and catalytic activity decrease.
Preparation Methods
Several methods exist for preparing nickel oxide, including:
High-Temperature Calcination: Heating NiCO3 or Ni(NO3)2·6H2O in a platinum crucible at 1000–1100°C for 6 hours, then cooling in N2 without O2.
Vacuum Heating: Placing NiCO3 in a pear-shaped decomposer, repeatedly filling and evacuating with N2 to remove air, then heating to 350°C under high vacuum.
Carbonate Nickel Method: Dissolving metallic nickel in sulfuric or nitric acid, adding soda ash to form nickel carbonate, then washing, drying, and burning.
Ammonia Method: Removing impurities like copper, iron, manganese, and chromium from nickel scrap using hydrogen sulfide, hydrogen peroxide, sodium carbonate, and ammonia water, then reacting with sulfuric acid to form nickel ammonium sulfate, which is then calcined and crushed.
Nickel Salt Calcination Decomposition: Purifying nickel alloy scraps (containing iron, copper, chromium, etc.) by removing impurities with hydrogen sulfide, hydrogen peroxide, sodium carbonate, and ammonia water, reacting with sulfuric acid to form nickel ammonium sulfate, which is then calcined and crushed to produce nickel oxide.
Applications
Nickel oxide has a wide range of applications, including
Ceramics and Glass Industry: Used as a pigment in ceramics and glass, as well as an adhesion promoter and colorant in enamel.
Magnetic Materials: Used in the production of nickel-zinc ferrites and other magnetic materials.
Battery Industry: Serves as a positive electrode material in nickel-metal hydride and nickel-cadmium batteries, improving cycle life and charge-discharge performance. It is also used as an electrode material in dye-sensitized solar cells to enhance photoelectric conversion efficiency.
Catalyst Industry: Widely used as a catalyst for hydrothermal synthesis, oxidation reactions, and reduction reactions, as well as an oxidant for CO and CH4 in waste gas purification and chemical production.
Metallurgy and CRTs: Used as a raw material for nickel salts, nickel catalysts, and in metallurgy and cathode ray tube (CRT) manufacturing.
Electronic Components: Used as a material for electronic components and battery materials.
Safety
Nickel oxide is harmful to human health, and precautions should be taken during handling. It may pose carcinogenic and sensitizing risks. During operation, wear appropriate protective clothing and gloves, avoid generating dust, and avoid contact with acids. Store away from ignition sources and heat, and separate from acids and edible chemicals.
Nickel oxide, as an important inorganic compound, has extensive applications in various fields. However, due to its potential hazards to human health, strict safety procedures must be followed during use and storage.