Multi-Path Electron Transfer in 1D Double-Shelled Sn@Mo2 C/C Tubes with Enhanced Dielectric Loss for Boosting Microwave Absorption Performance.

1D tubular micro-nano structural materials have been attracting extensive attention in the microwave absorption (MA) field for their anisotropy feature, outstanding impedance matching, and electromagnetic energy loss capability. Herein, unique double-shelled Sn@Mo2 C/C tubes with porous Sn inner layer and 2D Mo2 C/C outer layer are successfully designed and synthesized via a dual-template method. The composites possess favorable MA performance with an effective absorption bandwidth of 6.76 GHz and a maximum reflection loss value of -52.1 dB. Specifically, the rational and appropriate construction of Sn@Mo2 C/C tubes promotes the multi-path electron transfer in the composites to optimize the dielectric constant and consequently to enhance the capacity of electromagnetic wave energy dissipation. Three mechanisms dominate the MA process: i) the conductive loss resulted from the rapid electron transmission due to the novel 1D hollow coaxial multi-shelled structure, especially the metallic Sn inner layer; ii) the polarization loss caused by abundant heterogeneous interfaces of Sn-Mo2 C/C and Mo2 CC from the precise double-shelled structure; iii) the capacitor-like loss by the potential difference between Mo2 C/C nanosheets. This work hereby sheds light on the design of the 1D hierarchical structure and lays out a profound insight into the MA mechanism.