Key Takeaways & Executive Findings
- •• • Bi2Se3 nanosheets achieve a broad microwave absorption bandwidth of 2.95 GHz at sub-millimeter thickness, enabling effective EM attenuation in compact form factors. • • A multilayered design using a single Bi2Se3 absorbent realizes full-band absorption from 2 to 18 GHz, covering radar and communication bands without multiple materials. • • The Seebeck coefficient of -152 μV/K (measured over 0–110 °C) confirms thermoelectric conversion capability, allowing waste EM energy to be harvested as electricity. • • Morphology control via polyol reduction allows tuning of nanosheet thickness and size, directly influencing dielectric properties and absorption performance.
Abstract
The proliferation of high-frequency communication technologies has escalated electromagnetic (EM) pollution, posing risks to health and device reliability. Conventional microwave absorbers dissipate EM energy as heat, creating thermal management burdens and energy waste. This study introduces Bi2Se3 nanosheets, a topological insulator with surface conductivity and internal insulation, as a dual-functional material capable of both microwave absorption and thermoelectric conversion. Nanosheets with controlled morphology were synthesized via a polyol reduction method, with thickness and lateral size tuned by preparation conditions. The resulting composites exhibited excellent microwave absorption, achieving a broad absorption bandwidth of 2.95 GHz at sub-millimeter thickness. A multilayered structure design enabled full-band absorption from 2 to 18 GHz using a single absorbent. The Seebeck coefficient, derived from temperature differences up to 110 °C, was -152 μV/K, indicating efficient conversion of absorbed EM energy into electrical energy. This work demonstrates the potential of Bi2Se3 nanomaterials for self-powered electromagnetic devices, addressing both EM pollution and energy supply challenges.
1. Introduction
Electromagnetic (EM) pollution from high-frequency communication systems poses escalating risks to human health and the reliable operation of electronic infrastructure. Conventional microwave absorbers dissipate EM energy as heat, which not only creates thermal management burdens but also wastes recoverable energy. The challenge is to develop materials that not only absorb EM waves but also convert that energy into usable electrical power, enabling self-powered devices in remote or harsh environments.
Bi2Se3, a three-dimensional topological insulator, offers a unique combination of surface conductivity and internal insulation, along with a narrow bandgap (~0.3 eV) and high carrier mobility, making it a promising candidate for both microwave absorption and thermoelectric conversion. However, realizing both functions in a single material has been difficult due to the conflicting requirements of traditional absorbers and thermoelectric materials. This work addresses this bottleneck by synthesizing Bi2Se3 nanosheets with controlled morphology, demonstrating that precise thickness and size regulation can optimize dielectric loss and thermoelectric performance simultaneously.
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Junying Zhang, Xiaoyu Wang, Xuehao Liu, Jianing Cai, Peipei Ma, Song Bi, Zhi-Ling Hou (2026). Morphology-manipulated topological insulator Bi2Se3 nanosheets for integrated microwave absorption and thermoelectric conversion. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-4222-9
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Frequently Asked Questions
What is the maximum absorption bandwidth achieved and at what thickness?
The Bi2Se3 composites exhibit a broad absorption bandwidth of 2.95 GHz at sub-millimeter thickness, indicating efficient absorption across a wide frequency range in a thin layer.
How is full-band absorption from 2 to 18 GHz realized?
Full-band absorption is achieved through a multilayered structure design using only a single Bi2Se3 absorbent, which allows impedance matching and multiple internal reflections to cover the entire 2–18 GHz range.
What is the Seebeck coefficient and what does it imply for energy conversion?
The Seebeck coefficient is -152 μV/K, measured over a temperature difference range of 0 to 110 °C. This negative value indicates n-type thermoelectric behavior, and the magnitude suggests efficient conversion of absorbed electromagnetic energy into electrical voltage.
How does morphology control affect microwave absorption performance?
By controlling the thickness and lateral size of Bi2Se3 hexagonal nanosheets via polyol reduction conditions, the dielectric properties are tuned, which directly influences the impedance matching and attenuation characteristics, leading to optimized absorption bandwidth and intensity.
What are the potential applications of this dual-functional material?
The material can be used in self-powered electromagnetic devices, such as wireless sensors and micro-devices in aircraft or satellites, where it can absorb stray EM radiation and convert it into electricity to power low-energy electronics, reducing reliance on batteries and mitigating EM pollution.
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