Introduction to molybdenum trioxide

Molybdenum trioxide is a white or light green or light yellow crystalline powder, CAS No. 1313-27-5, molecular weight 143.94, bright yellow when heated, in a layered rhombohedral crystal system. Density 4.6926g/em3, melting point 795°C, boiling point 1155°C (sublimation). Stable in air, slightly soluble in water (0.68g/100mL water) and produces molybdic acid. Soluble in ammonia, soda ash and caustic soda, hydrofluoric acid and concentrated sulphuric acid, insoluble in common acids. Under heating it sublimates with hydrogen chloride to pale yellow needle-like crystals.

The most important structural feature of MoO3 is its structural anisotropy, and due to its special layered structure, molybdenum trioxide and its derivatives have been extensively studied.

Preparation of molybdenum trioxide

A variety of methods are available for the preparation of MoO3 films, such as vapour deposition, electrochemical deposition, sputtering and sol-gel methods.

Transition metal oxide films are usually prepared by vacuum vapour deposition, sputtering, chemical vacuum deposition, anodic oxidation and electrodeposition. Of these methods, electrodeposition is the most economical and can be used to produce large quantities of single oxide films easily.

Applications of molybdenum trioxide

1. Electrochromism and applications

The colour change of molybdenum trioxide is caused by the absorption of light through the valency of Mo, during which electrons and ions are injected into the interstices of the lattice to produce the colour change.

2. Gas-sensitive properties

MoO3 is a broadband semiconductor material with many active sites on its surface, which can selectively interact with the gas to be measured and thus has excellent gas-sensitive properties.

3. Catalytic degradation properties and applications

MoO3 has shown unique catalytic properties in some organic syntheses. Under certain wavelengths of light, the MoO3 surface is excited and electron-hole pairs are generated, resulting in a redox reaction in the medium, thus acting as a catalyst for the decomposition of organic pollutants.

4. Smoke suppression and applications

As a widely used polymer, the smoke produced by burning polyvinyl chloride (PVC) has long been a concern. When transition metal compounds are present in PVC, they can have a good smoke suppression effect.

5. Electrochemical de-lithiation properties

The unique layered structure of MoO3 crystals gives them interesting lithium ion insertion properties, and the ease with which oxygen vacancies can be created in MoO3 crystals makes MoO3 bodies an ideal electrode material for lithium ion batteries.

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MoO3 sputtering target