Integration of ZnO Nanotubes with Well-Ordered Nanorods through Two-Step Thermal Evaporation Approach

Abstract

We have successfully realized the integration of ZnO nanotubes and well-ordered nanorods through a simple two-step thermal evaporation of Zn powder without any metal catalyst. Detailed structural analysis shows that the step-one prepared samples at the low substrate temperature are composed of hexagonal-shaped Zn/ Zn suboxide nanowires dominated by Zn with little oxidation via the layer-by-layer growth mechanism. In the second step, by heating the step-one deposited samples and Zn powder at high temperature, highly ordered single-crystalline ZnO nanorods were epitaxially grown on the surface of nanowires through the screw dislocation growth mode. Simultaneously, Zn inside the nanowires sublimates to form hollow ZnO nanotubes, which finally results in the formation of ZnO nanotubes surrounded by well-ordered nanorods (ZNSWN). The field-emission scanning electron microscopy images of samples with different heating times indicate that the length of ZnO nanorods in the tube walls can be well controlled by changing the reaction time with a growth rate of ∼3 nm/min. We also further present the comparative X-ray diffraction, Raman, and photoluminescence investigation for the growth process and structural information of the fabricated ZNSWN nanostructures.

Catalyst-free growth and crystal structures of CdO nanowires and nanotubes

“…The formed Cd and CdO x molecules or clusters are transported to low-temperature region, absorb the surface of Si substrate, and then nucleate to form CdO nanoparticles. With continuous supplementation of CdO x , the flowing gas may induce turbulence in a certain growth condition, which results in the adsorption of fresh reactant gases on the tips [20]. Furthermore, the deposition of nanoclusters is extremely sensitive to the landing energy and orientation of the clusters.…”

Synthesis and optical properties of Mg-doped ZnO nanofibers prepared by electrospinning

“…Also two very weak and suppressed peaks at 332 and 580 cm −1 were also observed in the spectrum and assigned to the E 2H -E 2L and E 1L modes, respectively. And appearance of a very suppressed and short E 1L mode suggests that the formation defects (oxygen vacancies or zinc interstitials) [23] or impurities (Mg) existed in the synthesized nanofibers. Raman measurements show that both the undoped and Mg-doped ZnO nanofibers have a good crystal quality with hexagonal wurtzite structure, and little Mg doping does not change the structure of ZnO.…”

Growth of Ultra-Long ZnO Microtubes Using a Modified Vapor-Solid Setup

“…As members in the family of 1-D ZnO structures, wires and tubes have recently received much attention due to their unique structures and potential applications in the fields of piezoelectric generators, solar cells, surface modification, fog collection, and so on [24][25][26][27][28][29][30][31][32]. To the best of our knowledge, until now, a challenge still exists in the rational design and facile synthesis of long ZnO microtubes (MTs), although ZnO nanotubes [33][34][35][36][37] have been extensively studied in recent years.…”