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

In this paper, the controlled synthesis of WO 3– 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. WO 3– x nanowires with high concentrations of oxygen vacancy defects were synthesized in the air atmosphere, while WO 3– 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 WO 3– x nanostructures was studied. WO 3– x nanowires (exhibit) a higher emission current density and stability compared to that of WO 3– x nanosheets, which can be attributed to defect-enhanced conductivity. Our results are important for understanding the growth mechanism of the WO 3– x nanostructures and will prompt their applications in cold cathodes and other fields.