We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

Metal-organic framework (MOF) nanoparticles, also called porous coordination polymers, are a major part of nanomaterials science, and their role in catalysis is becoming central. The extraordinary variability and richness of their structures afford engineering synergies between the metal nodes, functional linkers, encapsulated substrates, or nanoparticles for multiple and selective heterogeneous interactions and activations in these MOF-based nanocatalysts. Pyrolysis of MOF-nanoparticle composites forms highly porous N- or P-doped graphitized MOF-derived nanomaterials that are increasingly used as efficient catalysts especially in electro- and photocatalysis. This review first briefly summarizes this background of MOF nanoparticle catalysis and then comprehensively reviews the fast-growing literature reported during the last years. The major parts are catalysis of organic and molecular reactions, electrocatalysis, photocatalysis, and views of prospects. Major challenges of our society are addressed using these well-defined heterogeneous catalysts in the fields of synthesis, energy, and environment. In spite of the many achievements, enormous progress is still necessary to improve our understanding of the processes involved beyond the proof-of-concept, particularly for selective methane oxidation, hydrogen production, water splitting, CO2 reduction to methanol, nitrogen fixation, and water depollution.

State of the Art and Prospects in Metal-Organic Framework (MOF)-Based and MOF-Derived Nanocatalysis.

As one important component of sulfur cathodes, the carbon host plays a key role in the electrochemical performance of lithium-sulfur (Li-S) batteries. In this paper, a mesoporous nitrogen-doped carbon (MPNC)-sulfur nanocomposite is reported as a novel cathode for advanced Li-S batteries. The nitrogen doping in the MPNC material can effectively promote chemical adsorption between sulfur atoms and oxygen functional groups on the carbon, as verifi ed by X-ray absorption near edge structure spectroscopy, and the mechanism by which nitrogen enables the behavior is further revealed by density functional theory calculations. Based on the advantages of the porous structure and nitrogen doping, the MPNC-sulfur cathodes show excellent cycling stability (95% retention within 100 cycles) at a high current density of 0.7 mAh cm −2 with a high sulfur loading (4.2 mg S cm −2 ) and a sulfur content (70 wt%). A high areal capacity (≈3.3 mAh cm −2 ) is demonstrated by using the novel cathode, which is crucial for the practical application of Li-S batteries. It is believed that the important role of nitrogen doping promoted chemical adsorption can be extended for development of other high performance carbon-sulfur composite cathodes for Li-S batteries.

Nitrogen-Doped Mesoporous Carbon Promoted Chemical Adsorption of Sulfur and Fabrication of High-Areal-Capacity Sulfur Cathode with Exceptional Cycling Stability for Lithium-Sulfur Batteries

Mixed transition-metal oxides (MTMOs), including stannates, ferrites, cobaltates, and nickelates, have attracted increased attention in the application of high performance lithium-ion batteries. Compared with traditional metal oxides, MTMOs exhibit enormous potential as electrode materials in lithium-ion batteries originating from higher reversible capacity, better structural stability, and high electronic conductivity. Recent advancements in the rational design of novel MTMO micro/nanostructures for lithium-ion battery anodes are summarized and their energy storage mechanism is compared to transition-metal oxide anodes. In particular, the significant effects of the MTMO morphology, micro/nanostructure, and crystallinity on battery performance are highlighted. Furthermore, the future trends and prospects, as well as potential problems, are presented to further develop advanced MTMO anodes for more promising and large-scale commercial applications of lithium-ion batteries.

Recent Developments and Understanding of Novel Mixed Transition-Metal Oxides as Anodes in Lithium Ion Batteries

Carbon-oxide and carbon-sulfide nanocomposites have attracted tremendous interest as the anode materials for Li and Na ion batteries. Such composites are fascinating as they often show synergistic effect compared to their singular components. Carbon nanomaterials are often used as the matrix due to their high conductivity, tensile strength, and chemical stability under the battery condition. Metal oxides and sulfides are often used as active material fillers because of their large capacity. Numerous works have shown that by taking one step further into fabricating nanocomposites with rational structure design, much better performance can be achieved. The present review aims to present and discuss the development of carbon-based nanocomposite anodes in both Li ion batteries and Na ion batteries. The authors introduce the individual components in the composites, i.e., carbon matrices (e.g., carbon nanotube, graphene) and metal oxides/sulfides; followed by evaluating how advanced nanostructures benefit from the synergistic effect when put together. Particular attention is placed on strategies employed in fabricating such composites, with examples such as yolk–shell structure, layered-by-layered structure, and composite comprising one or more carbon matrices. Lastly, the authors conclude by highlighting challenges that still persist and their perspective on how to further develop the technologies.

A Review on Design Strategies for Carbon Based Metal Oxides and Sulfides Nanocomposites for High Performance Li and Na Ion Battery Anodes

Synthesis of nitrogen and sulfur co-doped graphene supported hollow ZnFe2O4 nanosphere composites for application in lithium-ion batteries

PVD amorphous carbon coated 3D NiCo2O4 on carbon cloth as flexible electrode for both sodium and lithium storage

Hollow ZnSn(OH)6 boxes were synthesized from solid ZnSn(OH)6 cubes via an alkaline etching method followed by a calcination process. The as-prepared hollow boxes have an edge length ranging from 200 nm to 1 μm. Compared with the solid Zn2SnO4 cubes, hollow Zn2SnO4 boxes show an improved electrochemical performance (540 mA h g−1 at a current density of 300 mA g−1 after 45 cycles) and high rate capability (540, 482, 434, 353 and 300 mA h g−1 at the current densities of 300, 600, 1200 1800 and 2400 mA g−1, respectively). This class of hollow box-like structure may hold great promise for the development of high-performance lithium-ion batteries.

Preparation of hollow Zn2SnO4 boxes for advanced lithium-ion batteries

Fabricating three-dimensional hierarchical porous N-doped graphene by a tunable assembly method for interlayer assisted lithium-sulfur batteries

Novel hierarchically porous Ti-MOFs/nitrogen-doped graphene nanocomposite served as high efficient oxygen reduction reaction catalyst for fuel cells application

Ke Wang

Papers

Synthesis of nitrogen and sulfur co-doped graphene supported hollow ZnFe2O4 nanosphere composites for application in lithium-ion batteries

PVD amorphous carbon coated 3D NiCo2O4 on carbon cloth as flexible electrode for both sodium and lithium storage

Preparation of hollow Zn2SnO4 boxes for advanced lithium-ion batteries

Fabricating three-dimensional hierarchical porous N-doped graphene by a tunable assembly method for interlayer assisted lithium-sulfur batteries

Novel hierarchically porous Ti-MOFs/nitrogen-doped graphene nanocomposite served as high efficient oxygen reduction reaction catalyst for fuel cells application