Combination strategy of large interlayer spacing and active basal planes for regulating the microwave absorption performance of MoS2/MWCNT composites at thin absorber level

Haoran Geng; Yi Guo; Xuan Zhang; Yang Zhang; Xuelin Wang; Pengfei Zhao; Guizhen Wang; Jianhe Liao; Lijie Dong

doi:10.1016/j.jcis.2023.05.199

Combination strategy of large interlayer spacing and active basal planes for regulating the microwave absorption performance of MoS₂/MWCNT composites at thin absorber level

J Colloid Interface Sci. 2023 Oct 15:648:12-24. doi: 10.1016/j.jcis.2023.05.199. Epub 2023 Jun 3.

Authors

Haoran Geng¹, Yi Guo¹, Xuan Zhang¹, Yang Zhang¹, Xuelin Wang¹, Pengfei Zhao², Guizhen Wang³, Jianhe Liao³, Lijie Dong⁴

Affiliations

¹ Hainan Institute, Wuhan University of Technology, Sanya 572000, China.
² Key Laboratory of Tropical Crop Products Processing of Ministry of Agriculture and Rural Affairs, Agricultural Products Processing Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang 524001, China.
³ School of Materials Science and Engineering, Hainan University, Haikou 570208, China.
⁴ Hainan Institute, Wuhan University of Technology, Sanya 572000, China. Electronic address: dong@whut.edu.cn.

PMID: 37295364
DOI: 10.1016/j.jcis.2023.05.199

Abstract

Recently, molybdenum disulfide (MoS₂)/carbon has become a promising candidate for efficient microwave absorption. However, it is still challenging to simultaneously optimize the synergy of impedance matching and loss capability at the level of a thin absorber. Here, a new adjustment strategy is proposed by changing the concentration of precursor l-cysteine for MoS₂/multi-walled carbon nanotubes (MWCNT) composites to unlock the basal plane of MoS₂ and expand the interlayer spacing from 0.62 nm to 0.99 nm, leading to improved packing of MoS₂ nanosheets and more active sites. Therefore, the tailored MoS₂ nanosheets exhibit abundant sulfur-vacancies, lattice-oxygen, more metallic 1T-phase, and higher surface area. Such sulfur-vacancies and lattice-oxygen promote the electronic asymmetric distribution at the solid-air interface of MoS₂ crystals and induce stronger microwave attenuation through interface/dipole polarization, which is further verified by first-principles calculations. In addition, the expansion of the interlayer spacing induces more MoS₂ to deposit on the MWCNT surface and increases the roughness, improving the impedance matching and multiple scattering. Overall, the advantage of this adjustment method is that while optimizing impedance matching at the thin absorber level, composite still maintains a high attenuation capacity, which means enhancing the attenuation performance of MoS₂ itself offsets the weakening of the composite's attenuation ability caused by the decrease in the relative content of MWCNT components. Most importantly, adjusting impedance matching and attenuation ability can be easily implemented by separate control of l-cysteine content. As a result, the MoS₂/MWCNT composites achieve a minimum reflection loss value of -49.38 dB and an effective absorption bandwidth of 4.64 GHz at a thickness of only 1.7 mm. This work provides a new vision for the fabrication of thin MoS₂-carbon absorbers.

Keywords: High-performance absorbers; Lattice-oxygen; Molybdenum disulfide; Multi-walled carbon nanotubes; Sulfur-vacancies.