HMT-Controlled Synthesis of Mesoporous NiO Hierarchical Nanostructures and Their Catalytic Role towards the Thermal Decomposition of Ammonium Perchlorate

Abstract

In this work, mesoporous nickel oxide (NiO) hierarchical nanostructures were synthesized by a facile approach by hydrothermal reaction and subsequent calcination. The phase structure, microstructure, element composition, surface area, and pore size distribution of the as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and the Brunauer–Emmett–Teller (BET) technique. The precursor of Ni3(NO3)2(OH)4 nanosheet, Ni3(NO3)2(OH)4 microsphere, and Ni(HCO3)2 sub-microsphere was obtained by hydrothermal reaction at 160 °C for 4 h when the ratio of Ni2+/HMT (hexamethylenetetramine) was 2:1, 1:2, and 1:3, respectively. After calcination at 400 °C for 2 h, the precursors were completely transformed to mesoporous NiO hierarchical nanosheet, microsphere, and sub-microsphere. When evaluated as additives of the thermal decomposition of ammonium perchlorate (AP), these NiO nanostructures significantly reduce the decomposition temperature of AP, showing obvious catalytic activity. In particular, NiO sub-microsphere have the best catalytic role, which can reduce the high temperature decomposition (HTD) and low temperature decomposition (LTD) temperature by 75.2 and 19.1 °C, respectively. The synthetic approach can easily control the morphology and pore structure of the NiO nanostructures by adjusting the ratio of Ni2+/HMT in the reactants and subsequent calcination, which avoids using expensive templates or surfactant and could be intended to prepare other transition metal oxide.