Shujiang Ding

SnO2 nanosheets grown on graphene sheets with enhanced lithium storage properties

We demonstrate a new hydrothermal method to directly grow SnO(2) nanosheets on a graphene oxide support that is subsequently reduced to graphene. This unique SnO(2)/graphene hybrid structure exhibits enhanced lithium storage properties with high reversible capacities and good cycling performance.

Glucose-assisted growth of MoS2 nanosheets on CNT backbone for improved lithium storage properties

As a typical layered inorganic material, molybdenum disulfide (MoS2) has a similar structure to graphite. In the crystal structure of MoS2, each Mo(IV) sits in the center of a triangular prism, and is bound to six S atoms. Each S atom is connected to three Mo centers. In this way, the triangular prisms are interconnected to give a layered structure, wherein the Mo atoms are sandwiched between two layers of S atoms. Because of the weak van der Waals interactions between the sheets, MoS2 has a low friction coefficient; this gives rise to its superior lubricating properties. It has also been found attractive in many other application, including catalysts and transistors. Additionally, the layered structure of MoS2 enables easy intercalation of metal ions, such as Li or Mg . Many different MoS2 nanostructures, such as nanoflakes, nanotubes and nanoflowers, have been reported so far as anode materials for lithium ion batteries (LIBs). Although some of them show relatively high capacities of up to 1000 mAhg , the unsatisfactory cycling stability hinders their practical application as anode materials of LIBs. Some methods have been proposed to improve the cycling performance of MoS2, for example, construction of composite materials of MoS2 and conductive carbonaceous materials, like amorphous carbon, carbon nanotubes (CNTs), or graphene. For example, Li et al. reported a hybrid material of CNTs coated with several layers of MoS2. [15] When tested for lithium storage capabilities, the CNT@MoS2 hybrid structure shows a relatively good cyclic capacity retention with a reversible capacity of only up to 400 mAhg , probably due to the low mass fraction of MoS2 in the composite. Thus, obtaining a high content of MoS2 in the CNT@MoS2 is important for a better lithium storage capability. Many CNT-based hybrid structures have been prepared for different applications. 17] Herein, we report a simple glucose-assisted hydrothermal method to directly grow MoS2 nanosheets (NSs) on the CNT backbone (CNT@MoS2 NSs). The content of MoS2 in the hybrid structure is greatly increased because the shell is composed of sheet-like subunits. At the same time, the large surface area provided by this unique hierarchical structure can perhaps help to store more lithium, and the void space between these sheet-like subunits can buffer the volume change during the charge/ discharge processes, and lead to improved cyclic capacity retention. Furthermore, the carbon derived from glucose could ensure an excellent contact between the CNT backbone and the shell of MoS2 NSs, and give rise to a good conducting network. As expected, in comparison with pure MoS2 flakes, these CNT@MoS2 NS nanocomposites show enhanced lithium storage properties with better cyclic capacity retention and a higher reversible capacity. Figure 1 shows the morphology of the as-prepared CNT@MoS2 NSs. From the scanning electron microscopy

Bowl-like SnO2@Carbon Hollow Particles as an Advanced Anode Material for Lithium-Ion Batteries†

Despite the great advantages of hollow structures as electrodes for lithium-ion batteries, one apparent common drawback which is often criticized is their compromised volumetric energy density due to the introduced hollow interior. Here, we design and synthesize bowl-like SnO2 @carbon hollow particles to reduce the excessive hollow interior space while retaining the general advantages of hollow structures. As a result, the tap density can be increased about 30 %. The as-prepared bowl-like SnO2 @carbon hollow particles with conformal carbon support exhibit excellent lithium storage properties in terms of high capacity, stable cyclability and excellent rate capability.

Hierarchical nickel sulfide hollow spheres for high performance supercapacitors

Hierarchical NiS hollow spheres assembled from ultrathin nanosheets are synthesized by an efficient template-engaged conversion method. Silica nanospheres were used as templates, and SiO2@nickel silicate core-shell nanostructures were first prepared. In the presence of Na2S, the nickel silicate shell completely transformed into NiS nanosheetsvia a hydrothermal treatment, accompanied by the total dissolution of the inner SiO2 core. This gives rise to uniform hollow nanospheres whose shells are assembled from ultrathin NiS nanosheets. In virtue of the large surface area and enhanced structural stability, the as-prepared NiS hollow spheres exhibit excellent electrochemical performance as electrode materials for supercapacitors.

Controlled synthesis of hierarchical NiO nanosheet hollow spheres with enhanced supercapacitive performance

In this work, we report a facile strategy for the controlled synthesis of nickel oxide (NiO) hollow spheres (HSs) assembled from nanosheets (NSs). The Ni2CO3(OH)2 NSs are first grown on sulfonated polystyrene (sPS) hollow spheres by a low-temperature solution route. NiO HSs with well preserved morphology are then obtained by calcining the as-prepared sPS@ Ni2CO3(OH)2 NSs composite HSs. Because of the hollow interior and hierarchical structure, these NiO nanosheet hollow spheres have a relatively high specific surface area of 62 m2 g−1. When evaluated for supercapacitive performance, these hierarchical NiO HSs demonstrate improved electrochemical properties with a high capacitance of 415 F g−1 even at a high charge–discharge current rate of 3 A g−1 and 91% of which can be retained after 1000 charge–discharge cycles.

TiO2 hollow spheres with large amount of exposed (001) facets for fast reversible lithium storage

We report a simple approach for synthesizing uniform hollow spheres assembled from anatase TiO2 nanosheets with large amount of exposed (001) facets. These hierarchical TiO2 hollow spheres possessing a high specific surface area of 134.9 m2 g−1 manifest a high Coulombic efficiency for lithium extraction, excellent capacity retention, and superior rate behaviour owing to the hollow structure and unique crystal faceting of the building blocks.

Hierarchically structured one-dimensional TiO2 for protein immobilization, direct electrochemistry, and mediator-free glucose sensing.

A novel one-dimensional hierarchically structured TiO(2) (1DHS TiO(2)) was synthesized by a solvothermal method using multiwalled carbon nanotubes (MWCNTs) as a template and evaluated for the immobilization of protein and biosensing applications. Characterization studies showed that the 1DHS TiO(2) possessed an anatase crystalline structure and a large surface area with narrow pore size distribution. Fast direct electron transfer was observed for glucose oxidase (GOx) immobilized on the 1DHS TiO(2), and excellent electrocatalytic performance for glucose detection can be obtained without a mediator. The glucose sensor based on the GOx/1DHS TiO(2)-modified electrode had a high sensitivity of 9.90 μA mM(-1) cm(-2) and a low detection limit of 1.29 μM. The fabricated biosensor displayed good selectivity and long-term stability, indicating that the novel structured TiO(2) is a promising material for the immobilization of biomolecules and the fabrication of third-generation biosensors.

Hierarchical NiCo2O4 Nanosheets Grown on Ni Nanofoam as High‐Performance Electrodes for Supercapacitors

A high-performance electrode for supercapacitors is designed and synthesized by growing electroactive NiCo2 O4 nanosheets on conductive Ni nanofoam. Because of the structural advantages, the as-prepared Ni@NiCo2 O4 hybrid nanostructure exhibits significantly improved electrochemical performance with high capacitance, excellent rate capability, and good cycling stability.

Construction of hybrid bowl-like structures by anchoring NiO nanosheets on flat carbon hollow particles with enhanced lithium storage properties

Bowl-like hybrid structures have been designed and fabricated by anchoring NiO nanosheets on flat carbon hollow particles. When evaluated as an anode material for lithium-ion batteries, these unique NiO/carbon hybrid particles exhibit superior lithium storage properties in terms of high capacity, long term cycling stability and excellent rate capability.

An electrochemically formed three-dimensional structure of polypyrrole / graphene nanoplatelets for high-performance supercapacitors

A novel nanoplatelet-like structure of the composites of polypyrrole (PPy) and graphene (GR) is facilely synthesized by an electrochemical method and is further employed as a supercapacitor. The nanocomposite of PPy/GR shows a porous structure with a specific surface area of as high as 136.5 m2 g−1. As a result, the composite material exhibits a high specific capacitance of 285 F g−1 at a discharge rate of 0.5 A g−1, and excellent cycling stability. Specifically, over 90% of its initial capacitance can be retained after 1000 charge/discharge cycles. With advantageous features, such as facile fabrication process, high specific capacitance and excellent cycle life, this electrochemically synthesized PPy/GR nanocomposite is quite promising for high-performance supercapacitor applications.