A Catalyzed-Growth Route to Directly Form Micropatterned WO2 and WO3 Nanowire Arrays with Excellent Field Emission Behaviors at Low Temperature

By adjusting the type of catalysts, the controlled growth of micropatterned WO 2 and WO 3 nanowire arrays has been first accomplished at low temperature (450−600 °C). The as-prepared WO 2 and WO 3 nanowires are proven to be single crystalline structures with a single phase by Raman and transmission electron microscopy (TEM) techniques. Their formation mechanisms are attributed to the vapor−liquid−solid (VLS) mechanism. It is found that both micropatterned WO 2 and WO 3 nanowire arrays have very excellent field emission (FE) properties with quite low turn-on field (1.36 V/μm) and threshold field (2.38 V/μm), which is very similar to carbon nanotubes (CNTs) with best FE behaviors. In addition, the physical properties of an individual WO 2 and individual WO 3 nanowire are compared to probe the determinant factor for their different FE behaviors and understand their FE mechanism. Their very excellent FE performance suggests that this novel growth method is a useful technique for low-temperature preparation of micropatterned nanoemitter cathode arrays.