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 Ni 3 (NO 3 ) 2 (OH) 4 nanosheet, Ni 3 (NO 3 ) 2 (OH) 4 microsphere, and Ni(HCO 3 ) 2 sub-microsphere was obtained by hydrothermal reaction at 160 • C for 4 h when the ratio of Ni 2+ /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 Ni 2+ /HMT in the reactants and subsequent calcination, which avoids using expensive templates or surfactant and could be intended to prepare other transition metal oxide. Supplementary Materials:The following are available online at www.mdpi.com/xxx/s1, Figure S1:EDS spectrum of (a) NiO nanosheet; (b) NiO sub-microsphere, Figure S2: (a) Low-magnification TEM image, (b) highmagnification TEM image; and (c) HRTEM image of the precursor of Ni3(NO3)2(OH)4 microsphere.

Polypyrrole and a polypyrrole/nickel oxide composite – single-walled carbon nanotube enhanced photocatalytic activity under visible light

“…8(c), with the FFT pattern revealing the FCC crystalline structure of NiO nanoparticles having a 0.21 nm interplanar distance for the (200) planes in the SWCNT-containing polypyrrole matrix. 71,72 As shown by the selected area electron diffraction (SAED) pattern in Fig. 8(d), the indexed rings corresponding to the (1 1 1), (2 0 0), (2 2 0), and (3 1 1) planes have interplanar spacings of 0.24, 0.21, 0.14, and 0.13 nm, respectively, for the face-centred cubic NiO in the composite, which is consistent with the XRD data.…”

Nickel Hydroxide Nanoflake/Carbon Nanotube Composites for the Electrochemical Detection of Glutamic Acid using In Vitro Stroke Model

“…The synthesis of nickel hydroxide nanostructures was carried out at the n -butanol/water interface, with nickel nitrate in the aqueous phase and urea in the organic phase. Here, urea acts as an alkaline source and undergoes a decomposition reaction at the given temperature to produce ammonia, which then reacts with the precursor to form nickel hydroxide. , The proposed stoichiometric equations for the formation of nickel hydroxide are given below , 6 CO false( NH 2 false) 2 → normalC 3 normalH 6 normalN 6 + 6 NH 3 + 3 CO 2 Ni 2 + + 2 NH 3 + 2 normalH 2 normalO → Ni false( OH false) 2 + 2 NH 4 + However, it is reported that the concentration of the alkaline source might affect the morphology and physicochemical properties of the final product. , Hence, to study the role of alkaline source in controlling the morphology of the NHs, the concentration of the precursor nickel nitrate was fixed as 1 mmol, and the concentration of urea was altered (6, 12, and 18 mmol) to get the final products NH 1, NH 2, and NH 3, respectively. Both HRSEM analysis (Figure a–c) and HRTEM analysis (Figure d–f) revealed a transformation from a two-dimensional (2D) flake-like morphology to an agglomerated structure with increasing the concentration of urea.…”

“…However, it is reported that the concentration of the alkaline source might affect the morphology and physicochemical properties of the final product. 28,29 Hence, to study the role of alkaline source in controlling the morphology of the NHs, the concentration of the precursor nickel nitrate was fixed as 1 mmol, and the concentration of urea was altered (6, 12, It has been reported that increasing the concentration of urea in the reaction mixture causes the release of surplus OH − ions upon hydrolysis, which improves the grain boundaries, increasing the growth of nucleation centers and, thus, the nucleation rate. 30,31 Hence, at a lower urea concentration, as in NH 1, the nucleation process was much slower than the growth rate, resulting in the evolution of relatively larger 2D flakes.…”

Microwave absorption property of GO–Fe/FeO–NiO HNFs: GO decorated Fe/FeO–NiO hexagonal flakes with a 2D/0D/2D structure

“…Nickel oxide (NiO) is used as an important semiconductor application material in lithium-ion batteries, electrocatalysis, thermal catalysis, gas sensing, electrochemistry, optical sensing, fuel cell electrodes, and biosensors. 4…”

“…Nickel oxide (NiO) is used as an important semiconductor application material in lithium-ion batteries, electrocatalysis, thermal catalysis, gas sensing, electrochemistry, optical sensing, fuel cell electrodes, and biosensors. 4 Nickel oxide (NiO) is a p-type semiconductor with a band gap of 3.6 eV. Nano-scale nickel oxide has attracted a lot of attention due to its excellent physical and chemical properties, and new nanostructures have been made of nickel oxide, e.g., nanoparticles, nanosheets, and nanorods.…”