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 TiO2. Other application areas of WO3 are photoelectrocatalysis, photodegradation, gas sensors, biosensors, smart windows, and lithium-ion batteries.