Self-Assembled 3D Flower-Like Composites of Heterobimetallic Phosphides and Carbon for Temperature-Tailored Electromagnetic Wave Absorption

Bimetallic cobalt-nickel phosphides as a microwave absorber with a well-defined 3D hierarchical flower-like architecture featuring the ultrathin 2D subunits are very unusual and rarely reported. Herein, for the first time, we successfully prepared 3D flower-like CoNi-P/C composites with 2D nanosheet subunits via a one-pot solvothermal self-assembled strategy followed by a one-step carbonization–phosphorization process. Interestingly, the chemical composition and electromagnetic (EM) wave absorption performance of composites are highly influenced by the calcination temperature. As the calcination temperature increases from 300 to 500 °C, the crystal pattern transformed from CoP with nickel ions uniformly intercalating into the lattice to the CoNiP structure. Comparing with CoNi-P/C-400 and CoNi-P/C-500, the CoNi-P/C-300 sample exhibited an optimal reflection loss (RL) value of −65.5 dB at 12.56 GHz with a thickness of 2.1 mm and an ultralow filler loading of 15 wt %. Furthermore, the fundamental EM wave ab...