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175 results on '"Mao, Changjie"'

15. Highly active low-temperature HCHO oxidation of mesoporous Pt/CeO2 derived from Pt/CeBDC.

Author

Shi, Kangzhong, Lv, Shenjie, Hua, Zelin, Ruan, Chenxuanzhi, Liu, Xingpei, Wu, Nanhua, Mao, Changjie, and Li, Licheng

Subjects
OXIDATION, REACTIVE oxygen species, MESOPORES
Abstract

In the present work, mesoporous Pt/CeO2(MOF) was synthesized from Pt-containing CeBDC by high-temperature treatment for application in low-temperature HCHO oxidation. The catalytic results show that Pt/CeO2(MOF) possesses enhanced HCHO oxidation performance where its HCHO conversion rate is up to 78% while that of a commercial CeO2-supported Pt catalyst is only 31% at room temperature. Simultaneously, in a long-term HCHO oxidation experiment, Pt/CeO2(MOF) can remain catalytically stable. Kinetic studies demonstrate the more likely oxidation of HCHO molecules on Pt/CeO2(MOF). Structural characterization shows that Pt/CeO2(MOF) does not have an organic composition, which is elementally identical to that of a commercial CeO2-supported Pt catalyst. The Pt nanoparticles of Pt/CeO2(MOF) are mainly dispersed in the mesopores of CeO2 to significantly increase the number of Pt–O–Ce interfaces. Due to its structural characteristics, the mesoporous Pt/CeO2(MOF) possesses more reactive oxygen species, including peroxides (O22−). HCHO-DRIFTS studies demonstrate that the reaction rates of the two steps of HCHO decomposition, i.e. DOM transformation and CO oxidation, dramatically increase on Pt/CeO2(MOF). Moreover, the formate decomposition step of Pt/CeO2(MOF) is relatively faster than those of control catalysts. These factors could be responsible for the excellent low-temperature HCHO oxidation performance of the mesoporous Pt/CeO2(MOF). [ABSTRACT FROM AUTHOR]

Published
2023
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40. Enhanced the thermal conductivity of hydroxyl-terminated polybutadiene (HTPB) composites by graphene-silver hybrid

Author

Chen Jingshuai, Wu Mingyuan, Xiaolong Fu, Hongjian Yu, Wenjie Tao, Pengpeng Chen, Zhengzhong Zhang, and Mao Changjie

Subjects
Propellant, Nanocomposite, Fabrication, Materials science, Polymers and Plastics, Graphene, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, law.invention, Thermal conductivity, Polybutadiene, Hydroxyl-terminated polybutadiene, Mechanics of Materials, law, Materials Chemistry, Ceramics and Composites, Thermal stability, Composite material, 0210 nano-technology
Abstract

The heat conductivity affects the burning rate of propellant much, which would influence the properties of power propellant. In this work, hydroxyl-terminated polybutadiene (HTPB) was employed as a model propellant matrix, and series of composites were fabricated by introducing Graphene-Silver (GNs-Ag) hybrid as fillers to improve the heat conductivity of HTPB. GNs-Ag hybrids were prepared via chemical reduction of silver onto the graphene nanosheets, and the effect of preparation conditions on the fabrication of GNs-Ag were studied systematically. With the addition 0.5 wt% of GNs-Ag hybrid, the GNs-Ag/HTPB composites had a 52.6% increase in thermal conductivity compared with that of neat HTPB. The mechanical properties and thermal stability of the GNs-Ag/HTPB nanocomposites were also sightly improved.

Published
2021
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41. Tunable CO Dissociation Assisted by H2 over Cobalt Species: A Mechanistic Study by In‐situ DRIFTS.

Author

Shi, Kangzhong, Guo, Lisheng, Zhang, Wei, Jiang, Yong, Li, Da, Liu, Kai, Li, Mengmeng, Xue, Zhaoming, Sun, Song, and Mao, Changjie

Subjects
COBALT catalysts, COBALT, SPECIES, LIQUID fuels, SYNTHESIS gas
Abstract

Fischer‐Tropsch synthesis (FTS) is an important heterogeneous catalytic process that can effectively reduce human dependence on the non‐renewable petroleum resources. Cobalt is a crucial active metal center in most catalysts, which effectively catalyzes syngas into valuable products such as liquid fuels. On this basis, we systematically investigated the adsorption of CO on the surface of different cobalt species and its dissociation characteristics assisted by H2 are studied by the in‐situ DRIFTS. For the metallic cobalt phase, H2‐assisted CO dissociation not only possessed the FTS activity, but also inhibited the CO disproportionation reaction. However, for the CoO phase, the bidentate carbonate species were decomposed into CO2. In addition, CoO presented a high‐chain propagation ability than that of Co under the same operation conditions. Co2O3 and Co3O4 also exhibited similar CO dissociation patterns with the assistance of H2. However, different from CoO phase, formate species also formed under the H2 atmosphere over these two Co species. In summary, CO dissociation would be well tuned via the assistance of H2 as demonstrated by the in‐situ DRIFTS. This work provides a new sight on the rational design of efficient cobalt catalysts toward the FTS processes. [ABSTRACT FROM AUTHOR]

Published
2021
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46. Co2+ induced phase transformation from δ- to α-MnO2 and their hierarchical α-MnO2@δ-MnO2 nanostructures for efficient asymmetric supercapacitors.

Author

Guo, Yu, Li, Lei, Song, Li, Wu, Mingzai, Gao, Yuanhao, Chen, Jingshuai, Mao, Changjie, Song, Jiming, and Niu, Helin

Abstract

MnO2 possesses multiple crystal phases and various geometrical morphologies, so there remains a big challenge to simultaneously control the crystal phases and geometrical morphologies of MnO2 by a facile process. Indeed, these controllable syntheses will provide material bases to investigate their effects on the specific capacitance. Herein, benefiting from the first attempt of using Co2+ as a phase transformation-inducing agent and a doping ion, we present an interesting report on controllable phase transformation from δ- to α-MnO2 and their morphology evolution from nanosheets to nanowires. These transformations need the synergistic effect between MnCO3 and Co2+. Furthermore, three dimensional hierarchical α-MnO2@δ-MnO2 core–shell heterophase nanostructures were fabricated to improve capacitance performance. Impressively, the specific capacitance of α-MnO2@δ-MnO2 reaches up to 206 F g−1, which is higher than those of the corresponding single components. An asymmetric supercapacitor device based on the α-MnO2@δ-MnO2 cathode exhibits a good energy density of 12.9 W h kg−1 at a power density of 230 W kg−1 and excellent cycle lives with a decrease of 26% capacitance after 10 000 charge/discharge cycles. [ABSTRACT FROM AUTHOR]

Published
2019
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47. General Method for Large‐Area Films of Carbon Nanomaterials and Application of a Self‐Assembled Carbon Nanotube Film as a High‐Performance Electrode Material for an All‐Solid‐State Supercapacitor

Author

Song, Li, primary, Cao, Xuebo, additional, Li, Lei, additional, Wang, Qiaodi, additional, Ye, Huating, additional, Gu, Li, additional, Mao, Changjie, additional, Song, Jiming, additional, Zhang, Shengyi, additional, and Niu, Helin, additional

Published
2017
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