Janus Nanostructures Enabled by Confined Interfacial Engineering for Enhanced Electromagnetic Response.

Regulating electromagnetic responses through interfacial design has attracted increasing attention, while the precise construction and mechanism understanding of asymmetric nano-interfaces remain largely unexplored, particularly at the nanoscale. Herein, taking a representative carbon-based microwave absorber as a model system, we develop a confined diffusion-mediated interfacial engineering strategy to construct SiC@C Janus hollow nanostructures with well-defined asymmetric nano-interfaces, enabling the coordinated regulation of interfacial configuration and electromagnetic functionality. At an ultralow filler loading of 10 wt.%, the optimized composite achieves a minimum reflection loss of -62.36 dB, an effective absorption bandwidth of 7.82 GHz, together with a pronounced radar cross section reduction. Combined theoretical analysis, electromagnetic simulations, and multiscale characterizations reveal that the asymmetric Janus nano-interfaces promote improved impedance matching via refined dielectric modulation. Meanwhile, the coupling of the hollow architecture with heterogeneous interfaces induces multiple reflections, scattering, and interfacial polarization, thereby synergistically enhancing electromagnetic energy dissipation. This work provides nanoscale insights into the electromagnetic modulation mechanism governed by asymmetric Janus interfaces and establishes a general paradigm of confined interfacial engineering, offering new theoretical guidance and structural design strategies for next-generation high-performance electromagnetic protection materials.