Aggregated TiO2 nanotubes with high field emission properties

•P-TNTs are fabricated by electrochemical anodization techniques.•P-TNTs are transformed into A-TNTs after H2O2 post-treatment for 1 h.•A-TNTs cathodes possess higher levels of FE properties than the other cathodes.

A facile approach is developed to easily fabricate field emission (FE) cathodes based on TiO2 nanotubes with different geometrical structures at low temperature. Planar TiO2 nanotubes (P-TNTs) are first synthesized using the electrochemical anodization process with applied voltages of 20-50 V for 1 h at room temperature followed by thermal oxidation at 280 °C for 2 h under atmosphere ambient. P-TNTs can be transformed into aggregated TiO2 nanotubes (A-TNTs) after H2O2 post-treatment for 1 h at room temperature. FESEM, XRD, and Raman spectroscopy were used to analyze the surface morphology, crystallinity, and chemical binding, respectively. The A-TNTs fabricated with the applied voltages of 30-50 V cathodes possess higher levels of FE properties (lower turn-on electric field and higher current density) than the other cathodes due to their greater number of emission sites and decrement of the screening effect. The A-TNT with an applied voltage of 40 V cathode exhibits the lowest turn-on electric field (4.87 V/μm, 1 μA/cm2) and the highest enhancement factor β (1486). These superior properties indicate that the A-TNTs are promising field cathodes for future FE applications.