This paper reports the novel design of shell-in-shell Ni₃S₄@Co₉S₈ double-shelled tube (DST) hierarchical structures with different shell compositions, and the subsequent attempt to fabricate these structures. We fabricated such unique shell-in-shell hierarchical structures through transition from isomorphic metal–organic framework core–shell structures of Ni-MOF-74@Co-MOF-74 in the presence of Na₂S under solvothermal conditions. The as-prepared Ni₃S₄@Co₉S₈ DSTs demonstrated high specific capacity (up to 1257.4 F g⁻¹ at a current density of 4 A g⁻¹) with excellent charge–discharge reversibility (with 81.5% capacity retention after 1000 cycles), which is superior to that of the single-shelled Co₉S₈ tubes (337.8 F g⁻¹ at 1 A g⁻¹). The specific capacity of the prepared DST electrode also showed exceptional performance at a current density of 20 A g⁻¹. Approximately 74.0% of the obtained value of the specific capacity was retained at 1 A g⁻¹. This approach is a facile method to produce novel electrode materials for energy storage devices and a useful self-templated strategy for the preparation of multi-shelled hollow materials with different shell compositions for different functions.

中文翻译：

---

Ni-MOF-74 @ Co-MOF-74 空心壳中壳Ni ₃ S ₄ @Co ₉ S ₈管作为有效的法拉第电极†

本文报道了具有不同壳组成的壳内Ni ₃ S ₄ @Co ₉ S ₈双壳管（DST）分层结构的新颖设计，以及随后尝试制造这些结构的尝试。我们通过在溶剂热条件下在Na ₂ S存在下从Ni-MOF-74 @ Co-MOF-74的同构金属-有机骨架核-壳结构过渡制得了这种独特的壳-壳层级结构。所制备的Ni ₃小号₄ @Co ₉小号_8个DSTS证明高比容量（高达1257.4 F G ^-1在4 A G的电流密度^-1）具有优良的充放电可逆性（具有81.5％的容量保持1000次循环后），这是优于单去壳的Co ₉小号₈管（337.8 F G ^-1 1 A G ^-1）。所制备的DST电极的比容量在20 A g ^-1的电流密度下也表现出优异的性能。所获得的比容量的值的约74.0％保持在1A g ^-1。该方法是生产用于储能装置的新型电极材料的简便方法，并且是用于制备具有不同壳组成用于不同功能的多壳空心材料的有用的自我模板化策略。