Growth of flower-like ZnO on polyhedron CuO fabricated by a facile hydrothermal method on Cu substrate

Abstract

Flower-like ZnO on polyhedron CuO microstructures have been fabricated on Cu substrate via a simple hydrothermal method without any surfactant at low temperature (70°C). The time-dependent experiments indicated that flower-like ZnO and the polyhedron CuO crystallites were obtained when the reaction time is 30min and 1h, respectively. Based on these experiments, possible growth mechanism was proposed to account for the growth of the flower-like ZnO on polyhedron CuO. The different ionic radius and charge density of alkali metal hydroxide used to generate Zn(OH)42− ions have significant influences on the growth of ZnO. The different concentrations of alkali metal hydroxide result in different concentrations of Zn(OH)42−, which leads to the different rates of nucleation and crystal growth. The multinuclei aggregates serve as the sites for the intrinsic growth of one dimension ZnO to form early forms of flower-like ZnO microstructures under hydrothermal conditions. The strong electrolyte neutralizes the surface charges of the CuO, which causes the formation of dispersed CuO.