58 research outputs found

    Unique Fe<sub>2</sub>P Nanoparticles Enveloped in Sandwichlike Graphited Carbon Sheets as Excellent Hydrogen Evolution Reaction Catalyst and Lithium-Ion Battery Anode

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    The novel Fe<sub>2</sub>P nanoparticles encapsulated in sandwichlike graphited carbon envelope nanocomposite (Fe<sub>2</sub>P/GCS) that can be first applied in hydrogen evolution reaction (HER) as well as lithium-ion batteries (LIBs) has been designed and fabricated. The unique sandwiched Fe<sub>2</sub>P/GCS is characterized with several prominent merits, including large specific surface area, nanoporous structure, excellent electronic conductivity, enhanced structural integrity and so on. All of these endow the Fe<sub>2</sub>P/GCS with brilliant electrochemical performance. When used as a HER electrocatalyst in acidic media, the harvested Fe<sub>2</sub>P/GCS demonstrates low onset overpotential and Tafel slope as well as particularly outstanding durability. Moreover, as an anode material for LIBs, the sandwiched Fe<sub>2</sub>P/GCS presents high specific capacity and excellent cyclability and rate capability. As a consequence, the acquired Fe<sub>2</sub>P/GCS is a promising material for energy applications, especially HER and LIBs

    Ultrathin Two-Dimensional Free-Standing Sandwiched NiFe/C for High-Efficiency Oxygen Evolution Reaction

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    A NiFe-based compound is considered one of the most promising candidates for the highest oxygen evolution reaction (OER) electrocatalytic activities among all nonprecious metal-based electrocatalysts. In this report, a unique catalyst of free-standing sandwiched NiFe nanoparticles encapsulated by graphene sheets is first devised and fabricated. In this method, we use low-cost, sustainable, and environmentally friendly glucose as a carbon source, ultrathin Fe-doped Ni­(OH)<sub>2</sub> nanosheets as a precursor, and a sacrificial template. This special nanoarchitecture with a conductive network around active catalysts can accelerate electron transfer and prevent NiFe nanoparticles from aggregation and peeling off during long-time electrochemical reactions, thereby exhibiting an excellent OER activity and stability in basic solutions. In this work, our sandwiched catalyst presents well activities of a low onset of ∼1.44 V (vs RHE) and Tafel slope of ∼30 mV/decade in 1 M KOH at a scan rate of 5 mV/s

    Uniquely Monodispersing NiFe Alloyed Nanoparticles in Three-Dimensional Strongly Linked Sandwiched Graphitized Carbon Sheets for High-Efficiency Oxygen Evolution Reaction

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    Oxygen evolution reaction (OER) is known to have a significant role in renewable energy. Herein, we report a low-cost, highly active, and superbly durable three-dimensional (3D) sandwiched NiFe/C arrays grown on Ni foam by a general procedure. This special structure, with both graphitized carbon and Ni foam, possesses a huge specific surface area, high electroconductivity, and a porous structure, effectively enhancing electrocatalytic activities for OER. Furthermore, the sandwiched structure with coupled graphitized carbon sheets encapsulating the outside can hinder active materials from agglomeration and falling off during long-term operation, leading to outstanding durability, even in large temperature ranges

    Designed Functional Systems for High-Performance Lithium-Ion Batteries Anode: From Solid to Hollow, and to Core–Shell NiCo<sub>2</sub>O<sub>4</sub> Nanoparticles Encapsulated in Ultrathin Carbon Nanosheets

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    Binary metal oxides have been considered as ideal and promising anode materials, which can ameliorate and enhance the electrochemical performances of the single metal oxides, such as electronic conductivity, reversible capacity, and structural stability. In this research, we report a rational method to synthesize some novel sandwich-like NiCo<sub>2</sub>O<sub>4</sub>@C nanosheets arrays for the first time. The nanostructures exhibit the unique features of solid, hollow, and even core–shell NiCo<sub>2</sub>O<sub>4</sub> nanoparticles encapsulated inside and a graphitized carbon layers coating outside. Compared to the previous reports, these composites demonstrate more excellent electrochemical performances, including superior rate capability and excellent cycling capacity. Therefore, the final conclusion would be given that these multifarious sandwich-like NiCo<sub>2</sub>O<sub>4</sub>@C composites could be highly qualified candidates for lithium-ion battery anodes in some special field, in which good capability and high capacity are urgently required

    General and Green Strategy toward High Performance Positive Electrode Materials for Rechargeable Li Ion Batteries with Crop Stalks as the Host Carbon Matrixes

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    A novel, simple and universal approach toward the sheetlike carbon composites is presented here. In the method, an abundant agricultural byproduct (produced at a rate of 2.2 × 10<sup>7</sup> tons/year in China), obtained from the sustainable, environmentally friendly crop stalks, was used as a porous template for large-scale production of high performance cathode materials for lithium ion batteries. Owing to the large surface area, porous structure and small size of the functional particles, the nanocomposites manifest excellent electrochemical performance. Furthermore, the porous structure and charge transport property of the carbon materials can provide an electronic conductive network and promote the lithium ion extraction/insertion. In particular, the prepared LiFePO<sub>4</sub>/C composites present a high reversible capacity of 158 mAh g<sup>–1</sup> after 500 cycles, indicating crop stalks can be a massive resource for high performance lithium ion batteries

    Hierarchical Molybdenum Nitride Nanochexes by a Textured Self-Assembly in Gas–Solid Phase for the Enhanced Application in Lithium Ion Batteries

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    Self-assembly, as one kind of general phenomenon, has often been reported in solution chemistry. However, in gas–solid phase, it seldom has been disclosed. The MoN nanochex exhibits unique geometrical shape. Its body segment is composed of textured single crystal MoN nanowires, while its edges parallel to [1̅22̅] direction are attached by nanowires whose crystal orientation is different from that of the body segment. In this paper, the structure of the MoN nanochex is studied, and accordingly, a possible growth mechanism is proposed. We expect to extend this method to designed synthesis of many other functional materials, such as nitrides, carbides, and borides, and thereby to significantly tailor their resulting properties. Meanwhile, as one promising electrode material for Li-ion batteries (LIBs), MoN nanochex on Ti foil has been applied in the electrochemical energy storage, and stably delivered a specific capacity of 720 mAh/g with a remarkable Coulombic efficiency up to 98.5%, implying an achieved synergic effect derived from both mesoporous structure and the direct contact with the conducting substrate
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