Dielectric gene regulation and built-in electric field: A MXene-regulated ZnSe/SnO₂ heterojunction strategy for efficient electromagnetic absorption

Interface engineering has emerged as an application-oriented strategy for designing high-performance microwave absorbing materials (MAMs). Single-component dielectric absorbers usually suffer from poor energy dissipation, impedance mismatch, and unsatisfactory attenuation capability. In this work, a high attenuation design strategy is proposed by modulating MXene and ZnSe/SnO₂, obtained via selenization of a ZnSn(OH)₆ precursor, to achieve superior microwave absorption (MA) performance. Comprehensive experimental characterizations combined with first-principles calculations indicate that the semiconductor heterojunction (ZnSe/SnO₂) induces the formation of a built-in electric field (BIEF) at the interface. ZnSe/SnO₂@MXene, prepared by electrostatic self-assembly of few-layer MXene (f-MXene) and ZnSe/SnO₂, exhibits a three-dimensional (3D) gradient impedance structure for optimal impedance matching. Moreover, MXene enhances interfacial polarization effect by stimulating the BIEF in ZnSe/SnO₂, improving dielectric loss. These combined contributions lead to significantly enhanced electromagnetic waves (EMW) absorption performance. The optimized ZnSe/SnO₂@MXene exhibits exceptional MA properties, achieving a minimum reflection loss (RL_min) of −44.1 dB at a thickness of 2.3 mm. Therefore, this work provides a viable strategy for modulating the BIEF of ZnSe/SnO₂ by MXene.