CNT supported NiO hierarchal nanostructure on stainless steel substrate for efficient field emitters

Abstract

The field emission application has recently focused on assembling nanoscale building blocks into three-dimensional (3D) hierarchical or hybrid nanostructure. The hierarchical nanostructure provides better field emission than a single nanostructure. In the present study, the chemical vapor deposition (CVD) method was used to synthesize 1D carbon nanotube (CNT) on stainless steel (SS) substrate. Nickel (Ni) was then sputtered on the synthesized CNT, and the sputtered substrate was treated hydrothermally in LiOH solution. The deposited Ni on CNT forms Ni(OH)2, and after oxidation, it was converted to NiO nanostructure. The structure, morphology, and chemical state of the samples were characterized by XRD, FESEM, Raman spectroscopy, and XPS. The SS-CNT exhibited a turn-on field and maximum emission current of 5.5 V/μm and 275 µA/cm2, respectively. However, SS-CNT-Ni demonstrated reduced field emission responses with turn-on field and maximum current 8.7 V/μm and 68 µA/cm2, respectively. The field emission response has been enhanced in the case of the SS-CNT-NiO sample as compared to the other structures. The turn-on field and maximum current densities were 5.1 V/µm and 719 µA/cm2 for the SS-CNT-NiO, respectively.