Constructing NiP/NiP Heterostructures to Boost Interfacial Polarization for Enhanced Microwave Absorption Performance.

Heterostructures with a rich phase boundary are attractive for surface-mediated microwave absorption (MA) materials. However, understanding the MA mechanisms behind the heterogeneous interface remains a challenge. Herein, a phosphine (PH) vapor-assisted phase and structure engineering strategy was proposed to construct three-dimensional (3D) porous NiP/NiP heterostructures as microwave absorbers and explore the role of the heterointerface in MA performance. The results indicated that the heterogeneous interface between NiP and NiP not only creates sufficient lattice defects for inducing dipolar polarization but also triggers uneven spatial charge distribution for enhancing interface polarization. Furthermore, the porous structure and proper component could provide an abundant heterogeneous interface to strengthen the above polarization relaxation process, thereby greatly optimizing the electromagnetic parameters and improving the MA performance. Profited by 3D porous heterostructure design, P400 could achieve the maximum reflection loss of -50.06 dB and an absorption bandwidth of 3.30 GHz with an ultrathin thickness of 1.20 mm. Furthermore, simulation results confirmed its superior ability (14.97 dB m at 90°) to reduce the radar cross section in practical applications. This finding may shed light on the understanding and design of advanced heterogeneous MA materials.