Synthesis, structure, property, and applications of tungsten oxide based nanomaterials – A comprehensive review

Tungsten oxide-based nanomaterial is emerging as an advanced class of ceramics owing to its attractive combination of properties for wide varieties of application. It exists in both stoichiometric and non-stoichiometric configurations, such as WO 2 , WO 3 , WO 3-x type; where, x varies in the range of 0.1–0.3. The multi-oxidation states of tungsten oxide open up a plethora of possibilities to engineer the material at the atomic scale and achieve properties that was unthinkable a few decades ago. Properties of tungsten oxide-based nanomaterials can be varied by altering their structure, composition, and morphology. The structure, shape, size, and stoichiometric ratio of tungsten oxide-based nanoparticles depend on the processing conditions. At room temperature, even though the stable phase of tungsten oxide is monoclinic but hexagonal, orthorhombic, and cubic phases have also been synthesized. Tungsten oxide particles of various shapes, such as nanoplatelets, whiskers, urchin, nanowires, nanorods, quantum dots etc. have been produced. Among them, nanowires and hierarchical non-stoichiometric WO 3-x nanostructures have shown excellent electrochromic, NIR shielding, and gas sensing performances. However, a comprehensive review on process-structure-property-performance correlation is scanty. This review illustrates the progress made on various processing methods to synthesize tungsten oxide-based nanomaterials and draws a critical assessment on the role of process parameters on their structure, properties, and applications. The mechanism involved in various applications and factors affecting their performance are discussed. Finally, this article concludes highlighting the promising potential, existing knowledge gap, and future research direction in this field to expand its scope for practical applications. • WO 3 -based nanomaterials have emerged as promising candidate for many applications. • Methods for the synthesis of WO 3 -based nanomaterials are reviewed. • Critical analysis is made on process-structure-property correlations. • Mechanisms pertinent to various applications of WO 3 are discussed. • Ways to enhance the performance of WO 3 -based applications are summarized. • Strategy for future research on development of WO3 nanomaterials is highlighted.