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Wang P.,CAS Shenyang Institute of Metal Research
Dalton Transactions | Year: 2012

Ammonia borane (NH 3BH 3, AB) is a unique molecular crystal containing an intriguingly high density of hydrogen. In the past several years, AB has received extensive attention as a promising hydrogen storage medium. Several strategies have been successfully developed for promoting H 2 release and for suppressing the evolution of volatile by-products from the solid-state thermolysis of AB. Several potentially cost-effective and energy-efficient routes for regenerating AB from the spent fuels have been experimentally demonstrated. These remarkable technological advances offer a promising prospect of using AB-based materials as viable H 2 carriers for on-board application. In this perspective, the recent progresses in promoting H 2 release from the solid-state thermolysis of AB and in developing regeneration technologies are briefly reviewed. © 2012 The Royal Society of Chemistry.

Pei S.,CAS Shenyang Institute of Metal Research | Cheng H.-M.,CAS Shenyang Institute of Metal Research
Carbon | Year: 2012

Graphene has attracted great interest for its excellent mechanical, electrical, thermal and optical properties. It can be produced by micro-mechanical exfoliation of highly ordered pyrolytic graphite, epitaxial growth, chemical vapor deposition, and the reduction of graphene oxide (GO). The first three methods can produce graphene with a relatively perfect structure and excellent properties, while in comparison, GO has two important characteristics: (1) it can be produced using inexpensive graphite as raw material by cost-effective chemical methods with a high yield, and (2) it is highly hydrophilic and can form stable aqueous colloids to facilitate the assembly of macroscopic structures by simple and cheap solution processes, both of which are important to the large-scale uses of graphene. A key topic in the research and applications of GO is the reduction, which partly restores the structure and properties of graphene. Different reduction processes result in different properties of reduced GO (rGO), which in turn affect the final performance of materials or devices composed of rGO. In this contribution, we review the state-of-art status of the reduction of GO on both techniques and mechanisms. The development in this field will speed the applications of graphene. © 2011 Elsevier Ltd. All rights reserved.

Zhou Y.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2011

Superalloy CMSX-4 is directionally solidified and initiated by bicrystal seeds. It has been found that diverging boundaries are the most favorable location for stray grain formation. The phenomenon cannot be attributed to nucleation of crystals. A reasonable mechanism is the bending or detachment of side arms during extension of secondary arms and the development of tertiary branches at the diverging boundaries. Solute interaction of the neighboring dendrites increases the likelihood of bending or detachment and thus leads to an enhanced frequency of stray grains. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Du J.,CAS Shenyang Institute of Metal Research | Pei S.,CAS Shenyang Institute of Metal Research | Ma L.,CAS Shenyang Institute of Metal Research | Cheng H.-M.,CAS Shenyang Institute of Metal Research
Advanced Materials | Year: 2014

Carbon nanotube (CNT)- and graphene (G)-based transparent conductive films (TCFs) are two promising alternatives for commonly-used indium tin oxide-based TCFs for future flexible optoelectronic devices. This review comprehensively summarizes recent progress in the fabrication, properties, modification, patterning, and integration of CNT- and G-TCFs into optoelectronic devices. Their potential applications and challenges in optoelectronic devices, such as organic photovoltaic cells, organic light emitting diodes and touch panels, are discussed in detail. More importantly, their key characteristics and advantages for use in these devices are compared. Despite many challenges, CNT- and G-TCFs have demonstrated great potential in various optoelectronic devices and have already been used for some products like touch panels of smartphones. This illustrates the significant opportunities for the industrial use of CNTs and graphene, and hence pushes nanoscience and nanotechnology one step towards practical applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Qi W.,CAS Shenyang Institute of Metal Research | Su D.,CAS Shenyang Institute of Metal Research
ACS Catalysis | Year: 2014

Catalysis over carbon, especially nanocarbon, is an attractive topic in material science and chemical engineering fields due to its significant advantages compared with conventional metal or metal oxide catalysts. This paper summarizes the recent developments, basic concepts, and commonly accepted understandings on the nature of carbon catalysis in oxidative dehydrogenation reactions, including: introduction and comparison of various reaction systems; identity and quantity of active sites on carbon catalysts; mechanism for the reactions; and structure-selectivity relations for modified carbon catalysts. These fruitful conclusive achievements are the basis for in-depth comprehension of carbon-catalyzed oxidative dehydrogenation process at the molecular level, and many other efforts, such as detailed kinetic study, precisely controllable synthetic technique for nanocarbon catalysts, are still needed to further push carbon catalysis fields to practical applications. © 2014 American Chemical Society.

Wang S.,CAS Shenyang Institute of Metal Research
Physical Chemistry Chemical Physics | Year: 2011

Information on orbital hybridization is very important to understand the structural, physical, and chemical properties of a material. Results of a comparative first-principles study on the behaviours of orbital hybridization in the two-dimensional single-element phases by carbon, silicon, and germanium are presented. From the well-known three-dimensional hexagonal lonsdaleite structure, in which the atoms are in ideal sp3-bonding, the layer spacing along c-axis is gradually stretched to simulate the evolutions of structural and electronic properties from three-dimensional to two-dimensional lattice configurations in the three materials. A turning point of the total system energy due to the sp3 to sp2 transition is observed during this process in carbon. In contrast, no such phenomenon is found in silicon and germanium. The differences in electronic structure and bonding behaviour are further examined through comparative investigation of atomic angular-momentum projected density of states and electronic energy band spectrums of these materials. We demonstrate that the valence electronic orbital in the two-dimensional hexagonal crystals of Si and Ge shows sp 3-like behaviour for the partial hybridization of s and p z, which leads to their different lattice configurations to graphene. The role of π-bonds in stabilizing the flat configuration of graphene is also discussed. © the Owner Societies 2011.

Su D.S.,CAS Shenyang Institute of Metal Research | Su D.S.,Fritz Haber Institute of the Max Planck Society | Perathoner S.,Messina University | Centi G.,Messina University
Chemical Reviews | Year: 2013

Nanocarbon is a term increasingly used to indicate the broad range of carbon materials having a tailored nanoscale dimension and functional properties that significantly depend on their nanoscale features. CNT and graphene belong to this class of materials comprising many more types of carbon materials, such as nanofibers, -coils, -diamonds, -horns, -onions, and fullerene. The field of application of nanocarbon materials is large, because they possess electrical and thermal conductivity, as well as a mechanical strength and lightness that conventional materials cannot match. With the diversity of their structure, these characteristic values can be achieved over an extremely wide range of conditions. For these reasons, they are extensively studied in applications going from photonics and optoelectronics to biotech and nanomedicine, advanced electrodes, and polymer composites. It should be mentioned that for commercial applications a comprehensive understanding of the catalyst structure, bonding, and properties is desirable, but not strictly necessary, provided that the catalysts are well-reproducible and give superior performances.

Li S.X.,CAS Shenyang Institute of Metal Research
International Materials Reviews | Year: 2012

The effect of inclusion size on fatigue behaviour of high strength steels in the very high cycle fatigue (VHCF) regime (.10 7-10 9 cycles) is reviewed. Internal fatigue fractures of high strength steels in the VHCF regime initiate mostly at non-metallic inclusions. The critical inclusion size below which it is hard to initiate fatigue cracking of high strength steels in the VHCF regime is found to be about half the critical value characteristic of the high cycle fatigue (HCF) regime (about 10 5-10 7 cycles). A stepwise or duplex S-N curve is observed in the VHCF regime. The shape and form of the S-N curves are affected by inclusion size and other factors including surface condition, residual stress, environment and loading modes. Fatigue strength and fatigue life for high strength steels have been found to obey inverse power laws with respect to inclusion size D of the form σ w∝D -n1 and Nf∝D -n2 respectively. For fatigue strength, the exponent n 1 has been reported to be ∼0·33 in the literature for the HCF regime and, more recently, to fall in the range 0·17-0·19 for the VHCF regime. For fatigue life, the exponent n2 is reported to be ∼3 in the HCF regime, and in the range 4·29-8·42 in the VHCF regime. A special area was often observed inside a 'fish eye' mark in the vicinity of a non-metallic inclusion acting as the fracture origin for specimens having a long fatigue life. The major mechanisms of formation for this special area are discussed. To estimate the fatigue strength and fatigue life, it is necessary to know the size of the maximum inclusion in a tested specimen, and to be able to infer this value using data from a small volume of steel. The statistics of extreme value (SEV) method and the generalised Pareto distribution (GPD) method are introduced and compared. Finally, unresolved problems and future work required in studying the VHCF of high strength steels are briefly presented. © 2012 Institute of Materials, Minerals and Mining and ASM International Published by Maney for the Institute and ASM International.

Zhou G.,CAS Shenyang Institute of Metal Research | Li F.,CAS Shenyang Institute of Metal Research | Cheng H.-M.,CAS Shenyang Institute of Metal Research
Energy and Environmental Science | Year: 2014

With the advent of flexible electronics, flexible lithium-ion batteries have attracted great attention as a promising power source in the emerging field of flexible and wearable electronic devices such as roll-up displays, touch screens, conformable active radio-frequency identification tags, wearable sensors and implantable medical devices. In this review, we summarize the recent research progress of flexible lithium-ion batteries, with special emphasis on electrode material selectivity and battery structural design. We begin with a brief introduction of flexible lithium-ion batteries and the current development of flexible solid-state electrolytes for applications in this field. This is followed by a detailed overview of the recent progress on flexible electrode materials based on carbon nanotubes, graphene, carbon cloth, conductive paper (cellulose), textiles and some other low-dimensional nanostructured materials. Then recently proposed prototypes of flexible cable/wire type, transparent and stretchable lithium-ion batteries are highlighted. The latest advances in the exploration of other flexible battery systems such as lithium-sulfur, Zn-C (MnO2) and sodium-ion batteries, as well as related electrode materials are included. Finally, the prospects and challenges toward the practical uses of flexible lithium-ion batteries in electronic devices are discussed. This journal is © the Partner Organisations 2014.

Wang D.-W.,University of Queensland | Su D.,CAS Shenyang Institute of Metal Research
Energy and Environmental Science | Year: 2014

Heterogeneous nanocarbon materials are being increasingly investigated and deployed in numerous new technologies and devices for sustainable energy conversion and storage. Nanocarbons often consist of fullerene, graphene and carbon nanotubes. Their derivatives include quantum dots, nanofibres, nanoribbons, nanospheres/capsules and other nanostructured morphologies. The heterogeneous forms of these nanocarbons stem from the implantation of alien atoms into the aromatic carbon lattice or the covalent grafting of functional groups onto the carbon basal plane or edge sites. Heterogeneous nanocarbons have shown remarkable advantages in solar cells, water splitting, supercapacitors, lithium ion batteries and catalysis. This review focuses on recent progress in the experimental and computational studies of the roles of heteroatoms in heterogeneous nanocarbons for electrocatalytic oxygen reduction reaction (ORR). Critical perspectives are devoted to the ambiguous phenomena in this emerging research area. The long standing debate about the active sites is discussed with an emphasis on more rational development of advanced nanocarbon-based electrocatalysts for ORR. © The Royal Society of Chemistry.

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