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

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.

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Thermoelectric Generator Using Polyaniline-Coated Sb2Se3/β-Cu2Se Flexible Thermoelectric Films

Polymers ◽

10.3390/polym13091518 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1518

Author(s):

Minsu Kim ◽

Dabin Park ◽

Jooheon Kim

Keyword(s):

Electron Microscopy ◽

Electrical Conductivity ◽

Field Emission ◽

Photoelectron Spectroscopy ◽

Thermoelectric Generator ◽

Hydrothermal Reaction ◽

Water Evaporation ◽

Pani Film ◽

Portable Devices ◽

X Ray

Herein, Sb2Se3 and β-Cu2Se nanowires are synthesized via hydrothermal reaction and water evaporation-induced self-assembly methods, respectively. The successful syntheses and morphologies of the Sb2Se3 and β-Cu2Se nanowires are confirmed via X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), and field emission transmission electron microscopy (FE-TEM). Sb2Se3 materials have low electrical conductivity which limits application to the thermoelectric generator. To improve the electrical conductivity of the Sb2Se3 and β-Cu2Se nanowires, polyaniline (PANI) is coated onto the surface and confirmed via Fourier-transform infrared spectroscopy (FT-IR), FE-TEM, and XPS analysis. After coating PANI, the electrical conductivities of Sb2Se3/β-Cu2Se/PANI composites were increased. The thermoelectric performance of the flexible Sb2Se3/β-Cu2Se/PANI films is then measured, and the 70%-Sb2Se3/30%-β-Cu2Se/PANI film is shown to provide the highest power factor of 181.61 μW/m·K2 at 473 K. In addition, a thermoelectric generator consisting of five legs of the 70%-Sb2Se3/30%-β-Cu2Se/PANI film is constructed and shown to provide an open-circuit voltage of 7.9 mV and an output power of 80.1 nW at ΔT = 30 K. This study demonstrates that the combination of inorganic thermoelectric materials and flexible polymers can generate power in wearable or portable devices.

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A Facile Method to Construct MXene/CuO Nanocomposite with Enhanced Catalytic Activity of CuO on Thermal Decomposition of Ammonium Perchlorate

Materials ◽

10.3390/ma11122457 ◽

2018 ◽

Vol 11 (12) ◽

pp. 2457 ◽

Cited By ~ 6

Author(s):

Haifeng Zhao ◽

Jing Lv ◽

Junshan Sang ◽

Li Zhu ◽

Peng Zheng ◽

...

Keyword(s):

Thermal Decomposition ◽

Catalytic Activity ◽

Ammonium Perchlorate ◽

Photoelectron Spectra ◽

Gravimetric Analysis ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

X Ray ◽

Improved Performance ◽

Calcination Method

In this work, a mixing-calcination method was developed to facilely construct MXene/CuO nanocomposite. CuO and MXene were first dispersed in ethanol with sufficient mixing. After solvent evaporation, the dried mixture was calcinated under argon to produce a MXene/CuO nanocomposite. As characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and X-ray photoelectron spectra (XPS), CuO nanoparticles (60–100 nm) were uniformly distributed on the surface and edge of MXene nanosheets. Furthermore, as evaluated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), the high-temperature decomposition (HTD) temperature decrease of ammonium perchlorate (AP) upon addition of 1 wt% CuO (hybridized with 1 wt% MXene) was comparable with that of 2 wt% CuO alone, suggesting an enhanced catalytic activity of CuO on thermal decomposition of AP upon hybridization with MXene nanosheets. This strategy could be further applied to construct other MXene/transition metal oxide (MXene/TMO) composites with improved performance for various applications.

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Preparation and Characterization of Defective TiO2. The Effect of the Reaction Environment on Titanium Vacancies Formation

Materials ◽

10.3390/ma13122763 ◽

2020 ◽

Vol 13 (12) ◽

pp. 2763

Author(s):

Zuzanna Bielan ◽

Szymon Dudziak ◽

Agnieszka Sulowska ◽

Daniel Pelczarski ◽

Jacek Ryl ◽

...

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Photoelectron Spectroscopy ◽

Diffuse Reflectance Spectroscopy ◽

Hydrothermal Reaction ◽

High Photocatalytic Activity ◽

Paramagnetic Resonance ◽

X Ray ◽

Light Activity ◽

Cheap Alternative

Among various methods of improving visible light activity of titanium(IV) oxide, the formation of defects and vacancies (both oxygen and titanium) in the crystal structure of TiO2 is an easy and relatively cheap alternative to improve the photocatalytic activity. In the presented work, visible light active defective TiO2 was obtained by the hydrothermal reaction in the presence of three different oxidizing agents: HIO3, H2O2, and HNO3. Further study on the effect of used oxidant and calcination temperature on the physicochemical and photocatalytic properties of defective TiO2 was performed. Obtained nanostructures were characterized by X-ray diffractometry (XRD), specific surface area (BET) measurements, UV-Vis diffuse reflectance spectroscopy (DR-UV/Vis), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. Degradation of phenol as a model pollutant was measured in the range of UV-Vis and Vis irradiation, demonstrating a significant increase of photocatalytic activity of defective TiO2 samples above 420 nm, comparing to non-defected TiO2. Correlation of EPR, UV-Vis, PL, and photodegradation results revealed that the optimum concentration of HIO3 to achieve high photocatalytic activity was in the range of 20–50 mol%. Above that dosage, titanium vacancies amount is too high, and the obtained materials’ photoactivity was significantly decreased. Studies on the photocatalytic mechanism using defective TiO2 have also shown that •O2− radical is mainly responsible for pollutant degradation.

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The low temperature thermal decomposition of ammonium perchlorate: nitryl perchlorate as the reaction intermediate

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1984.0131 ◽

1984 ◽

Vol 396 (1811) ◽

pp. 425-440 ◽

Cited By ~ 31

Keyword(s):

Thermal Decomposition ◽

Low Temperature ◽

Ammonium Perchlorate ◽

Bond Formation ◽

Covalent Bond ◽

Subsequent Reaction ◽

Temperature Decomposition ◽

Covalent Bond Formation ◽

Localized Reaction

We identify nitryl perchlorate as the essential intermediate in the low temperature thermal decomposition of ammonium perchlorate AP. Evidence supporting this identification includes the analytical detection of an oxidized nitrogenous species in partly reacted AP and the ability of ammonium nitrate and several other nitrates to markedly reduce the induction period to decomposition of AP and to accelerate the subsequent reaction. It is also shown that the measured rate of the reaction of pure AP is in very satisfactory agreement with that estimated to result from this amount of NO 2 ClO 4 present. This mechanism differs from those currently accepted, in which the controlling process is believed to involve the transfer of either a proton or an electron. Our proposal is based on the known instability of NO 2 ClO 4 at reaction temperature ( ca . 500 K), the enhanced reactivity compared to the ionic alkali perchlorates being ascribed to covalent bond formation O 2 NO─ClO 3 . Subsequent reactions of the products of breakdown of this species, NO + , ClO 3 - and 2O or O 2 , are regarded as capable of oxidizing reactant NH 4 + (→NO 2 + ), thus regenerating the intermediate. Localized reaction in migrating ‘particles’ of fluid NO 2 ClO 4 , advancing through the reactant and leaving a residue of porous NH 4 ClO 4 , explains the unusual, incomplete low temperature decomposition that is characteristic of AP. The article reports comparative kinetic data for the decomposition of pure AP and the reaction initiated by various added nitrates. Rate studies are complemented by scanning electron microscope examinations of the geometry of interface development and the structure of the decomposed salt. From these and analytical results the role of nitryl perchlorate in AP decomposition is discussed.

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Hydrothermal Synthesis, Characterization, and Optical Properties of Ce Doped Bi2MoO6Nanoplates

Journal of Nanomaterials ◽

10.1155/2014/934165 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 5

Author(s):

Anukorn Phuruangrat ◽

Nuengruethai Ekthammathat ◽

Budsabong Kuntalue ◽

Phattranit Dumrongrojthanath ◽

Somchai Thongtem ◽

...

Keyword(s):

Electron Microscopy ◽

Optical Properties ◽

Photoelectron Spectroscopy ◽

Hydrothermal Reaction ◽

Growth Direction ◽

X Ray ◽

Selected Area Electron Diffraction ◽

Transmission Electron ◽

Uv Visible ◽

Bending Modes

Undoped and Ce doped Bi2MoO6samples were synthesized by hydrothermal reaction at 180°C for 20 h. Phase, morphology, atomic vibration, and optical properties were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectrophotometry, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and UV-visible spectroscopy. In this research, the products were orthorhombic Bi2MoO6nanoplates with the growth direction along the [0b0], including the asymmetric and symmetric stretching and bending modes of Bi–O and Mo–O. Undoped and Ce doped Bi2MoO6samples show a strong absorption in the UV region.

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Preparation of Carbon-Coated Nano-Fe, Co Particles and their Effects on the Thermal Decomposition of Ammonium Perchlorate

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.152-153.309 ◽

2010 ◽

Vol 152-153 ◽

pp. 309-314 ◽

Cited By ~ 1

Author(s):

Jun Zhao ◽

Wei Liang Zhou ◽

Fu Ming Xu

Keyword(s):

Thermal Decomposition ◽

Particle Size ◽

High Temperature ◽

Ammonium Perchlorate ◽

Cation Exchange Resin ◽

Carbon Matrix ◽

Decomposition Temperature ◽

Temperature Decomposition ◽

Carbon Coated ◽

Size And Morphology

Nano Metal/C (Metal=Fe, Co) composite materials, in which nano iron and cobalt particles were uniformly distributed in carbon matrix, was prepared by pyrolysis of M-exchanged cation exchange resin(M-PAA). X-ray diffraction (XRD), Transmission Electron Microscope (TEM) results showed the particle size and morphology of nano iron and cobalt in M/C could be controlled by pyrolytic temperature. The particle size of Co and Fe in M/C obtained at 500 was respectively 15-40 nm and 10-35 nm. DTA was employed to test the thermal decomposition of ammonium perchlorate (AP) in the M/C and AP mixture. Results indicated the decomposition temperature at high-temperature decomposition of AP was lowered with the addition of amount of M/C-500, and the high temperature decomposition peaks of AP respectively lowered as much as 145.2°Cand 68.3°C with adding amount of 5% of Co/C and Fe/C obtained at 500 . The high and low temperature decomposition peaks of AP overlapped with addition of Co/C.

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Well-Crystallized SnO2 Nanocrystals Homogeneously and Intimately Coated on Multiwalled Carbon Nanotubes by a Simple Surfactant-Free Hydrothermal Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.686.474 ◽

2011 ◽

Vol 686 ◽

pp. 474-481 ◽

Cited By ~ 1

Author(s):

Y.Q. Guo ◽

Rui Qin Tan ◽

Z.Y. Cao ◽

Wei Jie Song

Keyword(s):

Carbon Nanotubes ◽

Multiwalled Carbon Nanotubes ◽

Photoelectron Spectroscopy ◽

Gas Sensing ◽

Hydrothermal Reaction ◽

Ph Value ◽

Ethanol Solution ◽

Multiwalled Carbon ◽

X Ray ◽

In Situ Deposition

A simple approach to the in situ deposition of well-crystallized SnO2nanocrystals on the surface of multiwalled carbon nanotubes (MWCNTs) in the ethanol solution system of SnCl2 was presented in this paper. The well-crystallized SnO2nanocrystals with small and uniform crystal size (4~5 nm) can be tightly and homogenously coated on the outside surface of the MWCNTs entirely. The prepared nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen BET measurements. It is found that the hydrothermal reaction plays an important role for the crystal growth of the SnO2nanocrystals on the surface of MWCNTs, and the crystallinity of the SnO2nanocrystals can be controlled by varying the pH value or the hydrothermal reaction time. It is found that a unique structure of leaf-like SnO2nanosheets hanging on the MWCNTs was obtained when using water as the solvent of SnCl2instead of ethanol. The gas sensing performance of the SnO2/MWCNTs nanocomposites was also investigated.

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Evolution of the Micropore Structure of Ammonium Perchlorate during Low-Temperature Decomposition and Its Combustion Characteristics

Applied Sciences ◽

10.3390/app11209392 ◽

2021 ◽

Vol 11 (20) ◽

pp. 9392

Author(s):

Haijun Zhang ◽

Jianxin Nie ◽

Gangling Jiao ◽

Xing Xu ◽

Shi Yan ◽

...

Keyword(s):

Thermal Decomposition ◽

Low Temperature ◽

Ammonium Perchlorate ◽

Peak Pressure ◽

Rate Of Change ◽

Solid Propellants ◽

Multiple Points ◽

Temperature Decomposition ◽

Reaction Intensity ◽

Almost All

Ammonium perchlorate (AP) is a common oxidant in solid propellants, and its thermal decomposition characteristics at low temperatures (less than 240 °C) are key to the study of the thermal safety of propellants. Here, the low-temperature thermal decomposition characteristics of AP were investigated at 230 °C. The micromorphology of the low-temperature decomposition residues was characterized by scanning electron microscopy and 3D nano-computed tomography in order to analyse the evolution of microscopic pore structures, and the effect of the AP pore structure on combustion performance was then tested and analysed with a homemade closed bomb. The results demonstrate that the low-temperature decomposition of AP first occurs near the surface of the particles, simultaneously starting at multiple points and forming pores, and then gradually expands towards the interior until almost all of the pores connect with one other. Compared with ordinary AP, porous AP has a significantly improved combustion rate. When the ratio of porous AP to Al was 80:20, the peak pressure in the closed bomb was increased by 2.7 times; the rate of change in peak pressure increased 34 times, leading to a higher reaction speed and higher reaction intensity, and a typical explosion reaction occurred.

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Fabrication of Mo-Doped WO3 Nanorod Arrays on FTO Substrate with Enhanced Electrochromic Properties

Materials ◽

10.3390/ma11091627 ◽

2018 ◽

Vol 11 (9) ◽

pp. 1627 ◽

Cited By ~ 8

Author(s):

Bao Wang ◽

Wenkuan Man ◽

Haiyang Yu ◽

Yang Li ◽

Feng Zheng

Keyword(s):

Photoelectron Spectroscopy ◽

Response Times ◽

Hydrothermal Reaction ◽

Average Diameter ◽

Nanorod Arrays ◽

X Ray Diffraction ◽

Hydrothermal Temperature ◽

X Ray ◽

Electrochromic Properties ◽

Wo3 Nanorod

Well-oriented and crystalline WO3 nanorod arrays (WNRAs) decorated with Mo were synthesized on fluorine doped tin oxide (FTO) substrate by the hydrothermal method. The effects of Mo doping, hydrothermal reaction time, and hydrothermal temperature on the morphologies and electrochromic properties of as-prepared WNRAs were studied thoroughly. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and chronoamperometry techniques were used to characterize the structures and properties of obtained WNRAs. The results demonstrate that the average diameter of the as-prepared WNRAs ranged from 30 to 70 nm. During the decoration of Mo on the WNRAs, the growth density of as-prepared WNRAs decreased and the surfaces became rough. However, the decorated Mo on WNRAs synthesized at 180 °C for 5 h with a Mo/W mole ratio of 1:40 exhibited better electrochromic properties than single WNRAs. They exhibited high optical modulation (61.7%), fast bleaching/coloring response times (3 s/9 s), high coloration efficiency values (73.1 cm2/C), and good cycling stability.

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Optimization of Mesh-Based Anodes for Direct Methanol Fuel Cells

Journal of Fuel Cell Science and Technology ◽

10.1115/1.3117605 ◽

2010 ◽

Vol 7 (3) ◽

Cited By ~ 12

Author(s):

Raghuram Chetty ◽

Keith Scott ◽

Shankhamala Kundu ◽

Martin Muhler

Keyword(s):

Thermal Decomposition ◽

Fuel Cell ◽

Methanol Oxidation ◽

Photoelectron Spectroscopy ◽

Direct Methanol Fuel Cells ◽

Linear Sweep Voltammetry ◽

Effect Of Temperature ◽

X Ray ◽

Oxidation Of Methanol ◽

Direct Methanol

Platinum based binary and ternary catalysts were prepared by thermal decomposition onto a titanium mesh and were evaluated for the anodic oxidation of methanol. The binary Pt:Ru catalyst with a composition of 1:1 gave the highest performance for methanol oxidation at 80°C. The effect of temperature and time for thermal decomposition was optimized with respect to methanol oxidation, and the catalysts were characterized by cyclic voltammetry, linear sweep voltammetry, scanning electron microscopy, X-ray diffraction studies, and X-ray photoelectron spectroscopy. The best catalyst was evaluated in a single fuel cell, and the effect of methanol concentration, temperature, and oxygen/air flow was studied. The mesh-based fuel cell, operating at 80°C with 1 mol dm3 methanol, gave maximum power densities of 38 mW cm−2 and 22 mW cm−2 with 1 bar (gauge) oxygen and air, respectively.

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