Tungsten Trioxide Nanoparticles

Tungsten trioxide (WO₃) is a transition metal oxide. It is an important p-type semiconductor with a bandgap of 2.5-3.0 eV. The crystal structure of WO₃ can be orthorhombic, hexagonal, tetragonal or monoclinic. The crystal structure of this material is temperature dependant. Monoclinic ε-WO3 existing up to –27°C, triclinic WO3 (from –27 to 20°C), monoclinic WO3 (from 20 to 339°C), hexagonal WO3 (room temperature), orthorhombic WO3 (from 339to   740°C),   and tetragonal WO3   (from   740   to1470°C). WO₃ nanoparticles are found in the form of yellow powder. WO3 is an important p-type semiconductor with the optical tunable bandgap of 2.5-3.0 eV, high surface-to-volume ratio, high chemical stability, good biocompatibility, and quantum confinement. The narrow bandgap of this material has attracted attention for applications of electrochromic materials. Moreover, WO₃ can also improve the photoactivity of wide bandgap semiconductors, such as TiO_2. Other application areas of WO₃ are photoelectrocatalysis, photodegradation, gas sensors, biosensors, smart windows, and lithium-ion batteries.