Investigations On The Synthesis Of N-dopedcarbon Nanotube Based ZnO Template And The Performance Of The Field Emission

Controllable synthesis of N-doped Carbon nanotube （NCNT） is an important issue for its applications in many aspects, including field emission, energy cell and catalysis. However, it is difficult to obtain the NCNT with low cost and high purity. In this paper, NCNTs were prepared by using zinc oxide （ZnO） nanorod as a template without any catalyst. In addition, the field emission performances of NCNT were also tested.（1） The ZnO nanorod array （ZNA） was prepared on the silicon substrate by hydrothermal method. The influence factors for the morphology of ZNA, such as growth temperature, growth time and growth concentration, were investigated. The results show that ZNA can be obtained at the optimized conditions, i. e. the reaction temperature is 90 ℃, the reaction time is 6h, the concentration of the reaction solution is 0.01mM, and the concentration of PVP is 0.625g·L^-1; and the products were characterized by SEM and XRD;（2） NCNT was prepared using ZnO nanorods as template. First,ZnO-CNx core-shell nanostructure was fabricated by using pyridine as precursor, and then NCNT was successfully prepared by immersing ZnO-CNx nanostructure in the HCl solution. The effect of growth time on the morphology of NCNT was also investigated. When the pyridine flow was 0.082ml.min^-1, the temperature was 750 ℃, the flow of Ar was 200sccm,the reaction lasted for 10 min at atmospheric condition. The as-prepared products show good morphologies, and the products were confirmed by the characterizations of SEM, TEM and XPS;（3） The NCNT emitters show superior field emission properties, i.e.,the lower turn-on field, with a value of 0.60 V-μm^-1 and the lower threshold voltage of 2.20 V·μm^-1,as well as good emission stability, with only 10% fluctuation over 350 min with the pressure from 10’7 to 10’5 Pa.