Confined transformation of trifunctional Co2(OH)2CO3 nanosheet assemblies into hollow porous Co@N-doped carbon spheres for efficient microwave absorption

Zhe Zeng; Dewen Xu; Miao Li; Zhuoyue Liu; Renxin Xu; Dan Liu

doi:10.1016/j.jcis.2022.04.142

Confined transformation of trifunctional Co₂(OH)₂CO₃ nanosheet assemblies into hollow porous Co@N-doped carbon spheres for efficient microwave absorption

J Colloid Interface Sci. 2022 Sep 15:622:625-636. doi: 10.1016/j.jcis.2022.04.142. Epub 2022 Apr 28.

Authors

Zhe Zeng¹, Dewen Xu¹, Miao Li², Zhuoyue Liu¹, Renxin Xu³, Dan Liu⁴

Affiliations

¹ School of Materials Science and Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, China.
² Zhongkexin Engineering Consulting (Beijing) Co., Ltd, Yard 57, Yongding Road, Beijing 100039, China.
³ School of Materials Science and Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, China. Electronic address: xurenxin@whut.edu.cn.
⁴ Department of Chemistry, School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, China; Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory, Xianhu Hydrogen Valley, Foshan 528200, China. Electronic address: daniellliu@whut.edu.cn.

PMID: 35533478
DOI: 10.1016/j.jcis.2022.04.142

Abstract

Carbonaceous-magnetic composites are the most appealing candidates for electromagnetic wave absorption, and creating hollow interiors and nanopores in the composites is commonly recognized as an essential strategy to reinforce their overall performances. Herein, we propose a spatial confinement strategy mediated by Co₂(OH)₂CO₃ nanosheet assemblies for achieving highly dispersed Co nanoparticles into hollow porous N-doped carbon shells (HP-Co@NCS). Systematic multi-technique characterizations indicate that the Co₂(OH)₂CO₃ nanosheet assemblies simultaneously play a trifunctional role during the synthesis, including Co source, template of the hollow interior cavities, and micro-/mesopore porogen. The chemical composition can be modulated by simply varying the ratio of Co₂(OH)₂CO₃ and carbon source (dopamine). The optimized HP-Co@NCS absorber exhibits a well-defined hollow structure and unprecedented high porosity (specific surface area of 742 m² g^-1) even with a high metallic Co content of 35.8 wt%. These profitable structural characteristics can facilitate incident EM waves penetrating the absorber's interior and promoting multiple reflections and scattering. Therefore, the HP-Co@NCS absorber exhibits efficient microwave absorption ability with a minimum reflection loss of -39.0 dB at a thin thickness of 2.5 mm and an effective absorption bandwidth up to 5.5 GHz (12.5-18.0 GHz) at a thin thickness of 2.0 mm. This work provides a new methodology to design advanced carbonaceous-magnetic composite materials with hollow porous structures for microwave absorption.

Keywords: Hollow structure; Impedance matching; Metallic Co; Microwave absorption; Porous carbon.