An electrochemical approach towards the controllable synthesis of highly ordered and hierarchical zinc oxide dendritic crystals composed of hexagonal nanosheets: some insights into the stacking-assembly of the hierarchical architecture

Abstract

Herein, an electrochemical synthetic approach is presented to produce a highly ordered and hierarchical zinc oxide dendrite architecture composed of hexagonal nanosheets. By qualitatively analyzing the energy state under a dynamic electric field and temperature field, the synthesis procedure was validated to be mainly dominated by an electric field. We established an alternative understanding of the formation process of the hierarchical dendrite architecture from the perspective of the [Zn(OH)₄]²⁻ coordination tetrahedron, in which zinc was present in the form of zinc oxide formed via dehydration, and spliced growth between various [Zn(OH)₄]²⁻ coordination tetrahedrons was achieved. Moreover, the newly generated hexagonal nanosheets serve as a growth substrate and are supposed to accelerate the formation of zinc oxide dendrite architecture. Although crystal growth along the c-direction is preferred in two-dimensional zinc oxide nanostructures, we have found that anions can be adsorbed on the (0001) plane and significantly suppress the thermodynamically preferred growth direction. As a consequence, each prismatic plane along the m-orientation of the six {10–10} axes could grow epitaxially around the c-axis. The peculiar dendrite architectures and the corresponding layer-by-layer epitaxial growth mechanism may be applicable to the growth and analysis of other nanomaterials.