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107 results on '"Cheng, Jin-Bo"'

13. Porous Carbon/ZnO Composites Synthesized Using an Environmentally Friendly Metal–Polyphenol Network for Electromagnetic Wave Absorption.

Author

Cheng, Jin-Bo, Meng, Li-Peng, Zhao, Hai-Bo, Zhao, Chun-Xia, Li, Hui, and Wu, Yuan-Peng

Abstract

Composite materials made of transition metals/metallic oxides and porous carbon stemming from metal–organic frameworks (MOFs) have drawn tremendous attention within the field of electromagnetic wave absorption. However, the fabrication of most MOFs involves the use of toxic solvents and specially synthesized organic ligands; furthermore, high-pressure hydrothermal processes are commonly employed and are environmentally unfriendly and unsustainable. Herein, a Zn metal–polyphenol network (MPN) was developed by replacing organic ligands with biomass tannic acid at room temperature by using water and ethanol as solvents. The resulting MPN exhibited a microstructure and performance similar to those of MOFs. Subsequently, in situ pyrolysis of the Zn–tannic acid network was conducted to prepare porous carbon/ZnO (PC/ZnO) composites. The PC/ZnO composite pyrolyzed at 700 °C showed a strong reflection loss of −57.8 dB at a matching thickness of 3.5 mm, and a wide effective absorption bandwidth of 5.5 GHz was attained at 2.5 mm. The excellent electromagnetic wave absorption performance can be ascribed to the occurrence of multiple scattering events due to the porous structure, the moderate resistance loss of the porous carbon network, and the strong dipolar and interfacial polarization losses due to the ZnO nanoparticles and defect carbon. This study provides a convenient, environmentally friendly, sustainable, and tunable approach to prepare excellent broadband electromagnetic wave absorbers. [ABSTRACT FROM AUTHOR]

Published
2023
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29. Hierarchical Ti3C2Tx@ZnO Hollow Spheres with Excellent Microwave Absorption Inspired by the Visual Phenomenon of Eyeless Urchins.

Author

Wang, Yan-Qin, Zhao, Hai-Bo, Cheng, Jin-Bo, Liu, Bo-Wen, Fu, Qiang, and Wang, Yu-Zhong

Subjects
SPHERES, ELECTROMAGNETIC wave absorption, MICROWAVES, ELECTROMAGNETIC waves, ABSORPTION
Abstract

Highlights: Inspired by the photoreception mechanisms of urchins, the urchin-like Ti3C2Tx@ZnO hollow spheres are rationally designed as high-performance microwave absorbents by constructing ZnO nanoarrays onto the surface of Ti3C2Tx hollow spheres. Both experimental and theoretical simulation results demonstrate that the microstructure of urchin-like possesses giant advantages in electromagnetic wave absorption performance, which is superior to most absorbers with similar components. Ingenious microstructure design and rational composition selection are effective approaches to realize high-performance microwave absorbers, and the advancement of biomimetic manufacturing provides a new strategy. In nature, urchins are the animals without eyes but can "see", because their special structure composed of regular spines and spherical photosensitive bodies "amplifies" the light-receiving ability. Herein, inspired by the above phenomenon, the biomimetic urchin-like Ti3C2Tx@ZnO hollow microspheres are rationally designed and fabricated, in which ZnO nanoarrays (length: ~ 2.3 μm, diameter: ~ 100 nm) as the urchin spines are evenly grafted onto the surface of the Ti3C2Tx hollow spheres (diameter: ~ 4.2 μm) as the urchin spherical photosensitive bodies. The construction of gradient impedance and hierarchical heterostructures enhance the attenuation of incident electromagnetic waves. And the EMW loss behavior is further revealed by limited integral simulation calculations, which fully highlights the advantages of the urchin-like architecture. As a result, the Ti3C2Tx@ZnO hollow spheres deliver a strong reflection loss of − 57.4 dB and broad effective absorption bandwidth of 6.56 GHz, superior to similar absorbents. This work provides a new biomimetic strategy for the design and manufacturing of advanced microwave absorbers. [ABSTRACT FROM AUTHOR]

Published
2022
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40. Banana Leaflike C-Doped MoS2Aerogels toward Excellent Microwave Absorption Performance

Author

Cheng, Jin-Bo, Zhao, Hai-Bo, Cao, Min, Li, Meng-En, Zhang, Ai-Ning, Li, Shu-Liang, and Wang, Yu-Zhong

Abstract

We describe the design and manufacturing method of a lightweight C-doped MoS2aerogel with a special regular banana leaflike microstructure used for high-performance microwave absorbers. The aerogel precursor was first fabricated by a self-assembly process between alginate (Alg) and ammonium thiomolybdate (ATM), where Alg as a template was assembled with ATM into regular banana leaflike architectures along the ice growth direction during oriented freezing. After pyrolysis at 900 °C, the C-doped MoS2aerogels maintained low densities and porous hierarchal banana leaflike structures, where the banana leaves ranged in diameter from about 2 to 5 μm with the growth of small branches. Benefitting from these features, the C-doped MoS2aerogel possessed excellent microwave absorption performance in the frequency range of 2–18 GHz. The minimum reflection loss (RL) reached −43 dB at 5.4 GHz with a matching thickness of 4 mm, and the effective microwave absorption band (RL < −10 dB) reached 4 GHz (14–18 GHz) at a thickness of 1.5 mm. Our findings also provide strategies for designing MoS2aerogel nanostructures for electronic devices, catalysis, and other potential applications.

Published
2020
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