A facile low-temperature synthesis of hierarchical porous Co3O4 micro/nano structures derived from ZIF-67 assisted by ammonium perchlorate

2019 ◽  
Vol 6 (3) ◽  
pp. 715-722 ◽  
Author(s):  
Kun Zhao ◽  
Haitao Li ◽  
Shouqin Tian ◽  
Wenjuan Yang ◽  
Xiaoxia Wang ◽  
...  

Sub-micro hierarchical porous Co3O4 dodecahedra with a large specific surface area (106.11 m2 g−1) were synthesized by the thermolysis of ZIF-67 at a low temperature of 268 °C assisted by ammonium perchlorate (AP).

2013 ◽  
Vol 42 (2) ◽  
pp. 432-440 ◽  
Author(s):  
Nicole Zink ◽  
Franziska Emmerling ◽  
Tobias Häger ◽  
Martin Panthöfer ◽  
Muhammad Nawaz Tahir ◽  
...  

Author(s):  
Alexandr V. Agafonov ◽  
Konstantin V. Ivanov ◽  
Olga V. Alekseeva

Barium titanate powder with average particle size near 300 nm was produced using the low-temperature synthesis. It was established using scanning electron microscopy that at the thermal treatment, the particles gradually decrease with the formation of polydisperse aggregates. Based on the thermogravimetric analysis of the synthesized powder held in air for 4 months, it was shown that along with the low-temperature phase, the sample contains a high-temperature phase of carbonates, which removes at ~ 900 °C. Sorption characteristics of barium titanate thermally treated at various temperatures were obtained from the results of adsorption-desorption of nitrogen vapors. The specific surface area of the BaTiO3 powder was 76 m2/g. It was found that further heat treatment leads to a decrease in the specific surface area. The X-ray diffraction analysis of barium hydroxotitanil annealed at temperatures from 120 °C to 800 °C showed that the thermal treatment of the sample leads to the formation of a completely formed phase of barium titanate. The DSC temperature was used to determine the Curie temperatures for a HTB powder thermally treated in the temperature range from 120 to 800 °C. Dielectric spectra of suspensions of the synthesized powder were obtained during the heat treatment. <span style="opacity: 0;"> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . </span>


2008 ◽  
Vol 2 (2) ◽  
pp. 97-102 ◽  
Author(s):  
M.P. Savyak ◽  
I.V. Uvarova ◽  
T.M. Yarmola

Pd additives and atomic hydrogen can accelerate kinetic processes in molybdenum reduction from molybdenum trioxide with hydrogen at 350?C in the presence of carbon. Such a low temperature reduction process (starting temperature 300-350?C) promotes the formation of a thermodynamically unstable nanodispersed phase with the specific surface area of 280 m2/g, which may be related to the formation of the intermediate cubic molybdenum suboxide Mo1-xO, responsible for the preservation of the MoO3 faceting. The specific surface area of 280 m2/g corresponds to the particle size ~3 nm. The phase transformation leading to the formation of Mo2C in the MoO3-Pd-H2-C system at a relatively low temperature (650?C) is the result of relaxation of the high free energy in the thermodynamically unstable system. The carbide formation process at such a low temperature yields carbide with the specific surface area from 4 to 40 m2/g (depending on the carbide-forming component), which can be easy sintered. The morphology of this carbide inherits the faceting of the initial whiskerous trioxide molybdenum. The microhardness of the sintered samples is significantly higher than that of carbide produced traditionally at high temperature.


CrystEngComm ◽  
2021 ◽  
Author(s):  
Tao-Tao Lv ◽  
Huai-Zhong Xing ◽  
Hong-Mei Yang ◽  
Hui-Xiang Wang ◽  
Jing Shi ◽  
...  

A simple and efficient strategy for synthesizing high-performance crystalline catalyst Cu2O hollow spheres with a large specific surface area was demonstrated.


NANO ◽  
2020 ◽  
Vol 15 (07) ◽  
pp. 2050096
Author(s):  
Minhua Jiang ◽  
Xiaofang Yu ◽  
Ruirui Gao ◽  
Tao Yang ◽  
Zhaoxiu Xu ◽  
...  

Multi-element doped porous carbon materials are considered as one of the most promising electrode materials for supercapacitors due to their large specific surface area, abundant mesoporous structure, heteroatom doping and good conductivity. Herein, we propose a very simple and effective strategy to prepare nitrogen, sulfur co-doped hierarchical porous carbons (N-S-HPC) by one-step pyrolysis strategy. The effect of sole dopants as a precursor was a major factor in the transformation process. The optimized N-S-HPC-2 possesses a typical hierarchically porous framework (micropores, mesopores and macropores) with a large specific surface area (1284.87[Formula: see text]m2 g[Formula: see text] and N (4.63 atomic %), S (0.53 atomic %) doping. As a result, the N-S-HPC-2 exhibits excellent charge storage capacity with a high gravimetric capacitance of 360[Formula: see text]F g[Formula: see text] (1 [Formula: see text]A g[Formula: see text] in three-electrode systems and 178[Formula: see text]F g[Formula: see text] in two-electrode system and long-term cycling life with 87% retention after 10,000 cycles in KOH electrolyte.


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