Tungsten Oxide Nanostructures on Glass Substrate with Excellent Field Emission Properties for Cold Cathodes

In this paper, the controlled synthesis of WO3–x nanostructures on glass substrates was achieved by using a catalyst-free thermal oxidation method. The effects of the oxidation atmosphere on the growth of these nanostructures were investigated. The morphology, structure, and composition of the as-grown nanostructures were characterized. WO3–x nanowires with high concentrations of oxygen vacancy defects were synthesized in the air atmosphere, while WO3–x nanosheets with good crystallinity were obtained in the oxygen atmosphere. A stress-driven growth mechanism was proposed to explain the observed phenomena. In addition, the field emission from WO3–x nanostructures was studied. WO3–x nanowires (exhibit) a higher emission current density and stability compared to that of WO3–x nanosheets, which can be attributed to defect-enhanced conductivity. Our results are important for understanding the growth mechanism of the WO3–x nanostructures and will prompt their applications in cold cathodes and other fields.