Effective electron emitters by molybdenum oxide-coated carbon nanotubes core-shell nanostructures

Abstract

In this article, we showed that simple metal oxide coatings such as MoO3 can be an effective enhancer for carbon nanotubes (CNTs) in field emission (FE) performance. For comparison, the FE properties of the pristine vertically aligned multi-walled CNTs with the metal oxidecoated CNTs were investigated. The metal oxide coating of the pristine CNTs was carried out by metalorganic chemical vapor deposition (MOCVD) method at 400 °C using Mo(CO)6 as the precursor. The core-shell structure of the nanocomposite was studied by transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) results showed that the surface of the coating material was mainly MoO3. FE test indicated that the MoO 3-coated CNTs film exhibited an enhanced performance than the pristine CNTs with a turn-on field of 1.33 V μm-1 and a field enhancement factor β estimated to be ∼7000. Ultraviolet photoelectron spectroscopy (UPS) results confirmed a lower electron emission barrier height for MoO3-coated CNTs than for the pristine CNTs. The mechanism of the enhanced FE performance is discussed based on Schottky barrier effect. © Springer Science+Business Media, LLC 2011.