Synthesis, growth mechanism and room-temperature blue luminescence emission of uniform WO3 nanosheets with W as starting material

Uniform single-crystalline tungsten oxide (WO3) nanosheets have been synthesized in a large-scale with W powders as starting material. The results from the thermal stability measurements show that the as-synthesized WO3 nanosheets are anhydrous. Their thickness and length are ∼80 and ∼500 nm, respectively. They exhibit blue luminescence emissions at ∼431, 486 and 497 nm, UV emissions at ∼362 and 398 nm. The blue emissions are resulted from the band–band indirect transition and the UV emissions should be attributed to the defect states of WO3. The growth mechanism of the two-dimensional WO3 nanosheets is discussed.