Hierarchical ZnO hollow microspheres with exposed (001) facets as promising catalysts for the thermal decomposition of ammonium perchlorate

Abstract

Hierarchical porous ZnO hollow microspheres assembled from nanorods with exposed (001) facets on their external surface exhibited better catalytic activity for the thermal decomposition of ammonium perchlorate (AP) than the dispersed ZnO nanorods.

Atomic‐Layer‐Deposited ZnO on Carbon Black as High‐Performance Catalysts for the Thermal Decomposition of Ammonium Perchlorate

“…The LTD process comprises a series of chemical reactions, starting with electron transfer in the AP subsurface to yield NH 3 and HClO 4 , and the process ends with an NH 3 ‐covered surface such that the unreacted NH 3 accumulates on the surface. [2a], [2d] The HTD process is attributed to the oxidation of NH 3 by HClO 4 . [2e], [3a]…”

“…where β is the heating rate in degrees Celsius per minute, T p is the peak temperature, R is the ideal gas constant, E a is the activation energy, and A is the pre‐exponential factor. [2b], [2d], According to this equation, there is a linear correlation exhibited between the term ln( β/T p 2 ) and 1/ T p , and the kinetic parameter of the activation energy ( E a ) can be obtained from the slope of the fitted straight line. Pure AP, the AP/ZnO mixture, and the AP mixture with the ZnO/CB hybrid were investigated by using the DSC test at different heating rates from 5 to 20 K min –1 , showing that the peak temperature is dependent on the heating rate (Figure S3).…”

“…Tang. [2d] In the presence of the ZnO and ZnO/CB hybrid catalysts, the activation energy E a of the AP decomposition is significantly decreased to (84.1 ± 5.7) and (58.8 ± 2.9) kJ mol –1 , respectively. These results confirm that ZnO and ZnO/CB hybrids exhibit obvious catalytic activity for the thermal decomposition of AP.…”

“…ZnO, an important transition‐metal‐oxide‐semiconductor material, has many favorable properties, including a wide band gap, strong room‐temperature luminescence, excellent reactivity, nontoxicity, and most importantly, low cost, which has led to its widespread application in optoelectronic devices, gas sensors, and solar cells, and especially, in catalysis . The photocatalytic activity of ZnO has already been researched extensively, both domestically and abroad, while ZnO as a catalyst to facilitate the thermal decomposition of ammonium perchlorate (AP) is in its infancy . Here, AP is the most widely used oxidant in composite‐solid rocket propellants, and its thermal decomposition process has a great impact on the combustion performance of the propellant …”

Formation Mechanisms of ZnO Spherulites and Derivatives

“…Engineering of the surface structure in the micro-or nano-scale to expose a large percentage of {0001} facets has been reported for ZnO. [32][33][34][35] In the present work, the detailed formation processes of both ZnO spherulites and its derivative morphologies including disc decorated microspheres, sea urchin-like, mushroom-like and wood gyro-like microparticles were investigated. For the construction of spherulites, nucleation and development of ZnO nanocrystallites must take place inside a gel like organic substrate.…”