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Snowflake‐like MnO2@NiCo2O4 composites were successfully fabricated by employing crossed snowflake‐like MnO2 nanorods as cores and one‐dimensional (1D) NiCo2O4 nanoneedles as shells. Impressively, the MnO2@NiCo2O4 composites exhibited a highly efficient electromagnetic wave (EMW) absorbing capability, and the minimum reflection loss (RL) value reached −58.4 dB at 6.8 GHz for a thickness of 4.0 mm. The reasons for the improved EMW absorption capability of snowflake‐like MnO2@NiCo2O4 composites were analyzed. The unique core–shell structure, good impedance matching, and high dielectric loss were all found to be important contributors. Moreover, the interfacial polarization mainly stemmed from the heterostructure, a microcurrent generated from the 1D MnO2 nanorods and NiCo2O4 nanoneedles under alternating electromagnetic fields, and the synergistic effect from the different components were all beneficial to improve the EMW absorption performance. These results demonstrated that snowflake‐like MnO2@NiCo2O4 composites could be utilized as promising materials for practical EMW absorbing applications. [ABSTRACT FROM AUTHOR]

Ti 3 C 2 T x MXene exhibits great potential application in the microwave absorption (MA) field mainly due to its two-dimensional (2D) characteristic and high dielectric loss. However, their wide application is limited by the inferior properties of without magnetic loss and narrow bandwidth in microwave frequency range. Driven by the further demands of MA performance improvement, sandwich-like CoFe@Ti 3 C 2 T x composites are designed and successfully fabricated by in-situ reduction in the presence of hydrazine, and the minimum reflection loss (RL) value of −36.29 dB at 8.56 GHz could be achieved with the thickness of 2.2 mm. The enhanced microwave absorption of CoFe@Ti 3 C 2 T x composites should originate from the unique sandwich-like structure, good impedance matching characteristic, and enhanced interfacial polarization. In addition, the coating made by CoFe@Ti 3 C 2 T x composites located on the substrates of aluminum plate and fabric exhibited good heat dissipation capability, which was studied through thermal infrared images. This work provides a new avenue for exploring high-performance microwave absorbers of MXene-based magnetic materials. • The combination of 2D Ti 3 C 2 T x and 2D CoFe was achieved. • The addition of magnetic CoFe enhanced the absorbing properties of Ti 3 C 2 T x. • CoFe@Ti 3 C 2 T x composite coating showed good heat dissipation capability. [ABSTRACT FROM AUTHOR]

• The 1D TiO 2 offers strong anisotropy and the loaded 2D NiMoO 4 provides good impedance matching. • More interfacial polarization is introduced into the multi-component TiO 2 /NC/NiMoO 4. • Novel 1D/2D heterostructure enriches the absorption mechanism and improved MA performance. Synthetic scheme, 3D RL plot, and schematic illustration of MA mechanism of TiO 2 /NC/NiMoO 4 composites. The outer 2D NiMoO 4 and porous NC provided good impedance matching and dielectric loss, and multiple scattering behavior was introduced into the system. The 1D TiO 2 offered strong anisotropy and dielectric loss. Therefore, the excellent MA performance attributed to good impedance matching, strong dielectric loss, and more interfacial polarization loss from the unique 1D/2D hierarchical structure. [Display omitted] Designing hierarchical structure composite is a promising approach to overcome impedance mismatching, enrich energy loss, and acquire high microwave absorption (MA) capacity. However, obtaining stable hierarchical structure composite still remains difficulty due to the lack of precise design and uncontrolled growth. Herein, one dimensional (1D) TiO 2 nanobelts coated by N-doped carbon and two-dimensional (2D) NiMoO 4 nanosheets (TiO 2 /NC/NiMoO 4) were prepared and exhibited excellent MA ability, and the minimum reflection loss (RL min) value of it reached − 41.1 dB at 15.1 GHz with a thickness of 3.1 mm. The outer 2D NiMoO 4 and porous NC provided good impedance matching and dielectric loss, and multiple scattering behavior were introduced into the system. The 1D TiO 2 offered strong anisotropy and dielectric loss. Therefore, the excellent MA performance attributed to good impedance matching, strong dielectric loss, and more interfacial polarization from the unique 1D/2D hierarchical structure. [ABSTRACT FROM AUTHOR]