Easy growth of large-area tungsten oxide nanostructures and their field emission properties

In this paper large area tungsten trioxide (WO 3 ) nanosheets and nanoribbons are synthesized by directly heating tungsten plates covered with potassium iodide (KI). The field emission properties of the as-grown samples are systematically measured. A 10 μA/cm current density is obtained from both samples under a 5.5 V/μm average field, while the average fields that extracted a current density of 1.0 mA/cra were 8.2 and 11.1 V/μm for the nanosheets and nanoribbons, respectively. Also, the emission sites are found to distribute uniformly on the whole sample surface. In the preliminary test on the stability, the WO 3 nanosheets, which had larger surface area, exhibited better robustness than the WO 3 nanoribbons. These findings have demonstrated the application perspectives of nanometer-scale tungsten oxide as future cold electron sources.