Physics

Microsphere

Bandwidth (computing)

Reflection loss

Composite number

Absorption (acoustics)

Astronomy

Engineering

Hydrothermal circulation

Composite material

Metallurgy

Materials science

Microwave

Computer science

X band

Chemical engineering

Optoelectronics

Cobalt

SPHERES

Telecommunications

Advanced Functional Materials

Absorbers with lightweight, low filler loading and broad absorption band are highly desirable for electromagnetic wave absorption field. Here, hollow Co 1– x S microspheres constructed by nanosheets are fabricated via a facile synthetic method based on hydrothermal route. As an efficient wave absorber, the Co 1– x S hollow spheres demonstrate excellent microwave absorption performance. With a weight content of only 3 wt%, the maximum reflection loss (RL) can reach as strong as −46.1 dB at 13.92 GHz and its qualified frequency bandwidth (with RL value over −10 dB) remarkably achieves 5.6 GHz, covering 35% of the entire measured bandwidth. In addition, compared with other cobalt sulfides (such as CoS 2 and Co 9 S 8 ), the Co 1– x S microspheres with hollow structure exhibit more superior absorption intensity and broader qualified bandwidth. Therefore, this work provides a promising approach for the design and synthesis of hollow Co 1– x S microspheres with lightweight and high‐performance microwave absorption.

Tunable High‐Performance Microwave Absorption of Co1–xS Hollow Spheres Constructed by Nanosheets within Ultralow Filler Loading