Hierarchical ZnO Nanorod-Assembled Hollow Superstructures for Catalytic and Photoluminescence Applications

Abstract

In this study, hierarchically complex hollow cage-like superstructures assembled by ZnO nanorods have been successfully constructed with water-soluble biopolymer sodium carboxymethyl cellulose as crystal growth modifiers. The number of the hollow cage could be adjusted from single-cage, double-cage, multi-cage to connected-cage. A possible formation mechanism of the hollow superstructures has also been proposed. The catalytic study shows that these ZnO superstructures have good abilities to enhance propellant combustion of ammonium perchlorate (an important oxidizer used in solid rocket propellants), by decreasing its decomposition temperature to as low as 285 °C. Photoluminescence studies reveal that the increase in the cage number leads to an increase in the relative photoluminescence intensity around 500 to 700 nm, which might be attributed to the increase in radiative defects at the interface of the components of the ZnO hollow structure with the growth in cage number.

Effect of Water Content on the Morphology of ZnO Powders Synthesized in Binary Solvent Mixtures by Glycol Process

“…Figure 4 shows the DSC curves of both pure AP and the mixtures of AP with the ZnO structures obtained with 1.0 mmol of glycine and different amount of H 2 O at a 2% mass basis. From Figure 4a, the first endothermic peak at 245uC is due to the crystal transformation of AP from orthorhombic to cubic phase and the exothermic peak around 450uC corresponds to the thermal decomposition of AP 29,30 . From the DSC curves of the mixtures of AP and ZnO samples (Figure 4b-4f), the exothermic peaks corresponding to the thermal decomposition of AP occurred at temperatures around 300uC.…”

A Review on the Fabrication of Hierarchical ZnO Nanostructures for Photocatalysis Application

“…In addition, a co-surfactant template, including a triblock copolymer of complex polyethylene oxide-poly-propylene oxide-polyethylene oxide (PEO 20 -PPO 70 -PEO 20 , P 123 ) and absolute ethanol (EtOH), was employed to assist the formation of ZnO hollow spheres by Sun et al [51]. In another case, Yin et al [52] proposed a water-soluble biopolymer as soft templates used in producing hollow cage-like superstructures assembled by ZnO nanorods constructed with, and the number of the hollow cages could be adjusted by verifying the reaction time. Typically, the morphology of ZnO double-cage structures is as shown in Figure 4.…”

Facile Preparation of Macroporous Structures Assembled from Branched Cu2O Crystals

“…Glucose was used in the reduction of Cu 2+ ions to Cu + ions. The final Cu 2 O products were prepared by combining the reduction and dehydration of Cu(OH) 4 2− ions, which were produced by the reaction of Cu 2+ ions and OH − ions. The branched shapes of the Cu 2 O products are produced by a kinetically controlled reaction, so reaction conditions consisting of a high temperature and a short reaction time are required.…”

“…[1][2][3][4] Porous inorganic oxides can possess chemical and physical properties that are different to those of nonporous inorganic oxides because of their high surface areas and low densities. Recently, template-free methods for the synthesis of porous inorganic oxides have been developed, such as oriented attachment, Ostwald ripening, and the Kirkendall process.…”