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 absorption mechanism was proposed. The synergetic effects of dramatical attenuation ability and well-matched impedance endue CoNi-P/C-300 with superior microwave absorption performance. This work may be enlightening in promoting the development of heterobimetallic phosphides in the wave-absorbing field due to their intrinsic magnetism, higher electrical conductivity, as well as eco-friendly traits.