Interior Supported Hierarchical TiO2@Co3O4 Derived from MOF-on-MOF Architecture with Enhanced Electrochemical Properties for Lithium Storage

Metal-organic frameworks (MOFs)-derived materials are widely applied in functional materials with noble structures. Here, a well-designed strategy for generating hierarchical double-shelled nanoboxes is reported. Starting from the construction of hierarchical MOF-on-MOF architecture followed by a post-annealing treatment, hierarchical TiO2@Co3O4 nanoboxes are successfully synthesized with an interior TiO2 shell supporting the outer hollow-Co3O4-aggregates shell with a CoTiO3 intermediate layer. The TiO2@Co3O4 electrode displays a superior lithium storage performance in terms of high reversible capacity (920.5 mAh g(-1) after 150 cycles at 200 mA g(-1), 58.6 % higher than theoretical capacity), outstanding high-rate long-term cycling stability (838.6 mAh g(-1) after 600 cycles at 1000 mA g(-1), 44.5 % higher than theoretical capacity), and remarkable rate capability (good restorability at 2000 mA g(-1)). Furthermore, the morphology and electrochemical kinetic analysis proves that TiO2@Co3O4 has a more stable structure, higher capacitive contribution, and better Li-ion diffusion, which enhance the lithium-storage performance.