Crystalline-amorphous Ni3P@Nix(POy)z core-shell heterostructures as corrosion-resistant and high-efficiency microwave absorbents

The search for high-efficiency and anti-corrosive microwave absorption (MA) materials plays a paramount role in improving the environmental adaptability and survivability of military targets in the harsh chemical conditions. However, it still faces huge challenges and lacks systematic research. Herein, a well-designed heterostructure composed of crystalline Ni3P core and amorphous Ni-x(POy)(z) shell was successfully fabricated through a facile annealing and thermal phosphating strategy. Electrochemical analysis demonstrated that the Ni3P@Ni-x(POy)(z) heterostructures delivered strong corrosion resistance in acid, alkaline, and salt environment owing to the presence of surface amorphous Ni-x(POy), layer. Meanwhile, crystalline Ni3P/amorphous Ni-x(POy)(z) interface could trigger intensive interfacial polarization relaxation to strengthen microwave attenuation. Furthermore, abundant lattice defects, polar Ni-P bond, decreased band gap and intrinsic magnetism of Ni3P crystal endowed the Ni3P@Ni-x(POy)(z), heterostructures strong reflection loss (-43.1 dB), moderate absorption bandwidth (3.0 GHz) and ultra-thin thickness (1.3 mm). This work may provide an insight into the evaluation and development of corrosion-resistant microwave absorbents.