Theoretical and experimental results have revealed that the lithium-ion storage capacity for nitrogen-doped graphene largely depends on the nitrogen-doping level. However, most nitrogen-doped carbon materials used for lithium-ion batteries are reported to have a nitrogen content of approximately 10 wt% because a higher number of nitrogen atoms in the two-dimensional honeycomb lattice can result in structural instability. Here we report nitrogen-doped graphene particle analogues with a nitrogen content of up to 17.72 wt% that are prepared by the pyrolysis of a nitrogen-containing zeolitic imidazolate framework at 800°C under a nitrogen atmosphere. As an anode material for lithium-ion batteries, these particles retain a capacity of 2,132 mA h g À 1 after 50 cycles at a current density of 100 mA g À 1 , and 785 mAh g À 1 after 1,000 cycles at 5 A g À 1 . The remarkable performance results from the graphene analogous particles doped with nitrogen within the hexagonal lattice and edges.

An FeCo alloy covered with nitrogen doped graphene is prepared by direct annealing of Fe3[Co(CN)6]2nanoparticles, exhibiting efficient HER catalysis.

Although MnO has been demonstrated to be a promising anode material for lithium-ion batteries (LIBs) in terms of its high theoretical capacity (755 mA h g(-1)), comparatively low voltage hysteresis (<0.8 V), low cost, and environmental benignity, the application of MnO as a practical electrode material is still hindered by many obstacles, including poor cycling stability and huge volume expansion during the charge/discharge process. Herein, we report a facile and scalable metal-organic framework-derived route for the in situ fabrication of ultrafine MnO nanocrystals encapsulated in a porous carbon matrix, where nanopores increase active sites to store redox ions and enhance ionic diffusivity to encapsulated MnO nanocrystals. As an anode material for lithium-ion batteries (LIBs), these MnO@C composites exhibited a high reversible specific capacity of 1221 mA h g(-1) after 100 cycles at a current density of 100 mA g(-1). The excellent electrochemical performance can be attributed to their unique structure with MnO nanocrystals dispersed uniformly inside a porous carbon matrix, which can largely enhance the electrical conductivity and effectively avoid the aggregation of MnO nanocrystals, and relieve the strain caused by the volumetric change during the charge/discharge process. This facile and economical strategy will extend the scope of metal-organic framework-derived synthesis for other materials in energy storage applications.

Iron oxides are extensively investigated as anode materials for lithium-ion batteries (LIBs) because of their large specific capacities. However, they undergo huge volume changes during cycling that result in anode pulverization and loss of electrical connectivity. As a result, the capacity retention of the iron oxide anodes is poor and should be improved for commercial applications. Herein, we report the preparation of ultrasmall Fe2O3 nanoparticles embedded in nitrogen-doped hollow carbon sphere shells (Fe2O3@N-C) by the direct pyrolysis of Fe-based zeolitic imidazolate frameworks (Fe-ZIF) at 620 °C in air. As an anode material for LIBs, the capacity retained was 1573 mA h g(-1) after 50 cycles at a current density of 0.1 C (1 C = 1000 mA g(-1)). Even undergoing the high-rate capability test twice, it can still deliver a remarkably reversible and stable capacity of 1142 mA h g(-1) after 100 cycles at a current density of 1 C. The excellent electrochemical performance is attributed to the unique structure of ultrasmall Fe2O3 nanoparticles uniformly distributed in the shell of nitrogen-doped carbon spheres, which simultaneously solve the major problems of pulverization, facilitate rapid electrochemical kinetics, and effectively avoid the aggregation of Fe2O3 nanoparticles during de/lithiation. The novel method developed in this work for the synthesis of functional hybrid materials can be extended to the preparation of various MOFs-derived functional nanocomposites owing to the versatility of links and metal centers in MOFs.

Herein, we report a novel and facile route for the large-scale fabrication of 2D porous NixCo3-xO4 nanosheets, which involves the thermal decomposition of NixCo1-x hydroxide precursor at 450 °C in air for 2 h. The as-prepared 2D porous NixCo3-xO4 nanosheets exhibit an enhanced lithium storage capacity and excellent cycling stability (1330 mA h g(-1) at a current density of 100 mA g(-1) after 50 cycles). More importantly, it can render reversible capacity of 844 mA h g(-1), even at a high current density of 500 mA g(-1) after 200 cycles, indicating its potential applications for high power LIBs. Compared to pure Co3O4, the reduction of Co in NixCo3-xO4 is of more significance because of the high cost and toxicity of Co. The improved electrochemical performance is attributed to the 2D structure and large amounts of mesopores within the nanosheets, which can effectively improve structural stability, reduce the diffusion length for lithium ions and electrons, and buffer volume expansion during the Li(+) insertion/extraction processes.

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Porous MoO2@C nanocomposite was synthesized through the direct pyrolysis of NENU-5 and showed an excellent electrochemical performance (1442 mA h g−1 at 0.1 A g−1 for 50 cycles and 443.8 mA h g−1 at 1 A g−1 for 850 cycles) when tested as anode materials for LIBs.