A single step in-situ process for improvement in electron emission properties of surface-modified carbon nanotubes (CNTs): Titanium dioxide nanoparticles attachment

Abstract

Carbon nanotubes (CNTs) are excellent material for electron emission-based cold cathode devices application because of high aspect ratios, low turn-on and threshold field. In this present work, we have synthesized the as functionalized CNTs with TiO2 NPs (nanoparticles) for enhancing the electron field emission by single-step growth. The attachment of TiO2 NPs is a single step in-situ process. FESEM micrograph indicates the surface alteration/modification by attaching the TiO2 NPs. These nanoparticles enhanced the edge effect and reducing the screen effect. TEM micrograph reveals the uniform distribution of TiO2 NPs over the surface. The Raman spectra strongly indicate the active peaks of anatase TiO2 along with the D and G band of the CNTs and their intensity ratio (IG/ID) for pristine – CNTs and CNTs–TiO2 NPs which confirms it graphitic nature. Due to the attachment of TiO2 NPs to CNTs peaks shifting towards the higher frequency, reduced the work function to 2 eV, and enhanced the edge effect which means electron field emission site density increased and hence, reducing the screening effect. Electron emission analysis of CNTs–TiO2 NPs in contrast with pristine – CNTs showed a better low turn-on electric field (Eto) with the threshold field (Eth). The value of conventional characteristics field enhancement factor γ for CNTs–TiO2 NPs enhanced in comparison to pristine – CNTs. Excellent electron emission stability was also observed by both pristine – CNTs and CNTs–TiO2 NPs. In both samples, emission current becomes stable after 250 min. CNTs–TiO2 NPs had shown higher electron emission stability. CNTs–TiO2 NPs can be highly useful for electron emission-based vacuum device applications.