Heterogeneous core–shell ZIF-L(Zn)@ZIF-67 nanoleaves are controllably synthesized in aqueous media at room temperature in the light of our previously reported strategy. After direct carbonization under a nitrogen atmosphere, hierarchically porous amorphous carbon@graphite carbon core–shell nanoleaves with high nitrogen-doping content and carbon nanotubes (N-C@GC/CNTs) are obtained. The morphology, microstructure and the evolution process of N-C@GC/CNTs are systematically investigated by scanning electron microscopy, transmission electron microscopy, adsorption/desorption isotherms etc. All obtained N-C@GC/CNTs are employed to construct supercapacitors, and the results indicate that the optimized N-C@GC/CNTs exhibit a distinguished capacitance (252.1 F g⁻¹) and excellent stability (about 91.2% capacitance retention after 10 000 cycles) as supercapacitor electrodes due to their hierarchical pore structure, high nitrogen content and superior electrical conductivity resulting from graphitic structure and carbon nanotubes. This work not only extends our previously proposed strategy to synthesize heterogeneous core–shell of zeolitic imidazolate frameworks, but also provides a new avenue for preparing novel core–shell N-C@GC/CNTs with superior electrochemical performance.

The effects of Ti₃AlC₂ content on the physical, mechanical, and arc ablation resistance properties of a fabricated Cu–Ti₃AlC₂ composite are investigated in detail. Composite samples containing 10, 15, 20, 25, 30, and 35 vol.-% Ti₃AlC₂ are sintered at 800°C without decomposition of Ti₃AlC₂. It is demonstrated that with increasing Ti₃AlC₂ content, the relative density, electrical conductivity, and flexural strength of Cu–Ti₃AlC₂ decrease but the Brinell hardness first increases and then decreases. After eroded by an electric arc, Cu–Ti₃AlC₂ oxidises to CuO, TiO₂, and Al₂O₃. Meanwhile, field emission-SEM observations reveal that the dimensions of protrusions and the percentage of TiO₂ increase with increasing Ti₃AlC₂ content. Remarkably, the electric arc mainly occurs at the Ti₃AlC₂ particles, and the Cu matrix remains well protected.