Growth Behavior, Microstructure Characterization, and Field-Emission Property of 6-Fold Hierarchical Zn/ZnO Structures Prepared by Direct Annealing

Abstract

Six-fold core-shelled three-dimensional hierarchical structures were prepared by a direct annealing process. The effect of experimental parameters on density and length of branches of hierarchical Zn/ZnO structure is discussed. The influence of oxide layer formation and the shape of Zn polyhedron on the relaxation of stress for nanostructure growth also is reported. At the annealing temperature of 375 °C, the largest aspect ratio (∼71) of branched nanostructures and the smallest density (0.05 tips/μm2) of hierarchical arrays can be obtained. Transmission electon microscopy analysis shows that the oxide layer grows epitaxially from the Zn microtips and then the branches grow epitaxially from the oxide layer. For field emission applications, a better turn-on electric field (8.5 V/μm) and a larger enhancement factor 3490 are obtained for branched nanostructures with the high aspect ratio.

Fast Formation of Surface Oxidized Zn Nanorods and Urchin-Like Microclusters

“…Zn-ZnO core-shell structures are of special interest since heterojunctions can be formed at the interface. These structures offer great promise for fabrication of devices as nanotransducers [5], in solar energy conversion [6], and field emission [7], among others. Nowadays several methods are commonly applied to prepare Zn-ZnO core-shell structures such as urchin-like [6], nanoparticles [8], and nanorods [9].…”

Six-Fold-Symmetrical Hierarchical ZnO Nanostructure Arrays: Synthesis, Characterization, and Field Emission Properties

“…23 In the past few years, hierarchical ZnO micro-and nanostructures with different morphologies were synthesized via gas-phase and solution-phase approaches. 10,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] Nevertheless, how to assemble the as-prepared hierarchical ZnO nanostructures into arrays with excellent orientation has remained a challenge. In this study, we report the successful fabrication of aligned arrays of hierarchical ZnO nanostructures via a two-step vapor-phase transport method.…”

“…Some researchers utilize a self-catalyzed growth mechanism to control the growth of secondary branches on ZnO or Zn microprisms. 10,[26][27][28][29][30][31][32][33][34][35][37][38][39][40] The other researchers make use of the vapor-liquid-solid (VLS) growth mechanism with Sn as a catalyst to promote the growth of lateral branches on ZnO nanowires and nanorods. 24,25 On the basis of SEM and TEM results, we regard that the growth of the as-prepared 6-fold-symmetrical hierarchical ZnO nanostructure arrays is dominated by a twostep VLS mechanism with Au as the catalyst.…”

One-dimension-based spatially ordered architectures for solar energy conversion

“…9a). 122 The influence of annealing temperature and time on the growth kinetics for the branched nanostructures illustrated that the length of the nanowhiskers and the density of hierarchical structures are a function of the annealing time and temperature, respectively ( Fig. 9c and d).…”