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.