Nanocurvature-Activated Dipolar Polarization in M-N₄ Single-Atom Sites for High-Performance Electromagnetic Wave...

Area of Science:

• Materials Science
• Nanotechnology
• Electromagnetics

Background:

• Single-atom (SA) absorbers face limitations in dielectric response due to symmetric M-N4 coordination, hindering electromagnetic wave (EMW) attenuation.
• Existing methods struggle to overcome the inherent symmetry constraints of planar M-N4 sites.

Purpose of the Study:

• To introduce a nanocurvature-driven strategy to break symmetry and enhance dielectric polarization in SA absorbers.
• To explore the impact of geometric regulation on the performance of SA-based EMW attenuation materials.

Main Methods:

• Utilized click chemistry and template-assisted synthesis to anchor metal SAs onto hollow nitrogen-doped carbon spheres.
• Systematically modulated local nanocurvature by tuning the diameter of the carbon spheres.
• Performed theoretical calculations and experimental analyses to investigate electronic and dielectric properties.

Main Results:

• Curvature-induced surface charge accumulation disrupted electronic symmetry at Ni-N4 centers, enhancing charge density, dipole moments, and polarizability.
• The optimized Ni/HNC-200 absorber achieved a minimum reflection loss of -74.1 dB (390% enhancement) and reduced radar cross section to -70.49 dB m2.
• Demonstrated over fivefold suppression of electric-field radiation from mobile phone chips using a flexible electronic patch.

Conclusions:

• Nanocurvature is an effective geometric strategy for breaking symmetry and activating dielectric polarization in SA sites.
• This approach establishes a new design paradigm for high-performance single-atom EMW absorbers, validated in Ni, Co, and Cu systems.
• The findings pave the way for advanced materials with superior electromagnetic wave attenuation capabilities.