Construction of two-dimensional thick sheet-like carbide and Co nanocrystals heterostructure toward efficient electromagnetic wave absorption

Deeply studied the electromagnetic wave absorption (EWA) mechanism of Mo₂C heterostructure is crucial for realizing the application of Mo₂C-based materials in new multifunctional integrated microwave absorbing coatings. In order to exclude the influence of special three-dimensional morphology (spherical, hollow, etc) on EWA performance, we designed the two-dimensional (2D) thick sheet-like Mo₂C/Co@NC heterostructure that composed of molybdenum carbide (Mo₂C), cobalt (Co) nanoparticles and nitrogen-doped carbon (NC), derived from the MoO₄²⁻ substituted 2D sheet-like Co zeolite imidazolate frameworks (Mo/Co BIFs). The Mo₂C/Co@NC has better EWA performance than Co@NC and Mo₂C@NC. In the thickness range of 2∼4 mm, the effective absorption bandwidth can cover up to 10.5 GHz, and the strongest absorption can reach −48 dB. Behind the excellent EWA performance, multiple polarization relaxation and enhanced interface polarization are acting together. Moreover, the structure and interface effects of Mo₂C/Co heterojunction are also revealed by DFT calculation. This work provides a workable methodology for manipulating the heterogeneous interface of MOFs-derived Mo₂C based material and understanding the EWA mechanism of Mo₂C-based heterostructure.