Nano-Structured Proton Exchange Membrane for Fuel Cell

Nano-structured materials are characterized by long range ordering of the nano-dimensioned quantum dot units. They have been found to deliver substantially different （electric, optical, magnetic and physical） properties from that of the bulk. The differences are mainly due to the increases of surface charge with large fraction of grain boundaries, and the periodical potential field created by the ordered nano-domains. Specifically, the issues considered in “nano ionics” are the degree of interaction, the charge distribution on the interfaces where they become obvious in ionic properties and thermodynamics such as mobility of charge carriers. Major efforts in this direction are focused on：     

Paleosols and climates in the quaternary of south America

Numerous paleosols have been described in the Quaternary as well as a few paleosols in pre-Quaternary rocks of South America. A broad ordering of the more important occurrences of paleosols show four main regions for pedogenesis: A) The lowlands adjacent to the South Atlantic (the Pampa and surrounding areas) with typical loess-paleosol and similar sequences. B) The Andes, characterized by paleosols intercalated with moraines, as high as 4000 m.a.s.l., which are frequently developed in pyroclastic materials. C) The Caribbean region, where soil-forming processes underwent the following succession: Oxisols in the Lower Quaternary → Ultisols → Alfisols → Vertisols → Entisols in the Holocene. D) The Amazonian region located almost permanently under udic moisture regimes of different types. The soils are typically Oxisols and Ultisols.     

Progress in research on the performance and service life of batteries membrane of new energy automotive

Batteries membrane materials are widely used in new energy automotives such as hybrid vehicles,fuel cell vehicles,and pure electric vehicles.Membrane consists of two categories:fuel cell membrane(power unit) and power battery membrane(charge and discharge device).With rapid development of the processes and technology of cell membrane materials,there is urgent need to study their properties and service life.The article summarizes the recent research progress in proton exchange membrane materials,lithium battery separator materials,and nickel-hydrogen battery separator materials.Based on our laboratory research,the paper features the affecting factors and mitigation strategy of performance and service life for automotive battery membrane materials.Future direction for the batteries membrane material of new energy automotive is discussed.     

Magnetocaloric effect in Gd<Subscript>5</Subscript>Si<Subscript>1.85</Subscript>Ge<Subscript>2.15</Subscript> prepared by Gd metal with lower purity

Recently, Pecharsky et al. have discovered that Gd5(SixGe1-x)4 (0 < x <0.5) has a significantly large mag-netocaloric effect (MCE), which is 50% to 200% larger than any known materials[1—4]. This behavior is called as 慻iant magnetocaloric effect? The giant MCE is caused by simultaneous magnetic and crystallographic transition in these alloys. The first order magnetic ordering tem-perature of Gd5(SixGe1-x)4 can be tuned from 20 to 280 K by changing the ratio of Si︰Ge[2]. The temperat…     

Experimental study on CO2/CO of typical lining materials in full-scale fire test

Lining materials are widely used in buildings to cover walls and ceilings. Combustible linings may produce a potential high fire hazard in buildings. Once ignited, it propagates fire and accelerates the enclosure fire growth. Two types of lining materials were studied during the tests： block board and plywood. The test was conducted in an ISO 9705 room, where linings were mounted on walls without the ceiling. By changing the heat output of the burner, the ventilation, etc., the concentrations of CO2/CO of different lining materials were researched. The effect of test conditions on the production of CO2/CO of different lining materials was investigated, and useful experimental data were provided for the further development of numerical modeling to simulate enclosure fire growth lined with combustible materials.     

Transport dynamics analysis in ferromagnetic heterojunction using Raman spectroscopy and magnetic force microscopy

The ZnO/La_(0.7)Sr_(0.3)MnO_3 thin fi lm was epitaxially fabricated on La Al O3(100) by pulse laser deposition.The Raman scattering on the single layer La Sr Mn O and junction ZnO/La_(0.7)Sr_(0.3)MnO_3 was investigated in a giant softening by 490 cm~(-1)John-Teller, 620 and 703cm~(-1) optical phonon modes. The Raman spectra La Sr Mn O and ZnO/La_(0.7)Sr_(0.3)MnO_3 were observed with distinct features, i.e., the thickness was in dependent of frequency and intensity. The dynamics results showed that the spin–orbital coupling was caused by anomalies tilt of Mn O6 octahedron. The LSMO/Zn O junction exhibited excellent junction positive magneto-resistance behavior in the temperature range of 77–300 K. The kinetic energy gain was achieved by orbital competition, strong crystal fi eld and charge order of energy band splitting. The transport orbits were in the environment of the ferromagnetic-orbital ordering. The structures of barriers could be adjusted by junction interface and domain boundary condition in terms of the presence of spin–orbital fl uctuating.     

Electrification of mineral particles by electron beam irradiation

A novel way for electrification of mineral particles by electron beam irradiation was proposed.The effect of irradiation dose on charge/mass ratio was investigated experimentally.The charge/mass ratio of electrified mineral powders after irradiation was measured by an instrument based on the principle of electrostatic induction.The experimental results showed that the charge/mass ratio is largely dependent on radiation dose and electric physical properties of minerals.The mechanism of electrification by electron beam irradiation is discussed.It is suggested that the essential of electrification by electron beam irradiation is a process of retardation and charge deposition of incideent elecytrons in materials.     

Understanding supercapacitors based on nano-hybrid materials with interfacial conjugation

The recent fast development of supercapacitors,also known scientifically as electrochemical capacitors,has benefited significantly from synthesis,characterisations and electrochemistry of nanomaterials.Herein,the principle of supercapacitors is explained in terms of performance characteristics and charge storage mechanisms,i.e.double layer(or interfacial) capacitance and pseudo-capacitance.The semiconductor band model is applied to qualitatively account for the pseudo-capacitance in association with rectangular cyclic voltammograms(CVs) and linear galvanostatic charging and discharging plots(GCDs),aiming to differentiate supercapacitors from rechargeable batteries.The invalidity of using peak shaped CVs and non-linear GCDs for capacitance measurement is highlighted.A selective review is given to the nano-hybrid materials between carbon nanotubes and redox active materials such as electronically conducting polymers and transition metal oxides.A new concept,"interfacial conjugation",is introduced to reflect the capacitance enhancement resulting from π-π stacking interactions at the interface between two materials with highly conjugated chemical bonds.The prospects of carbon nanotubes and graphenes for supercapacitor applications are briefly compared and discussed.Hopefully,this article can help readers to understand supercapacitors and nano-hybrid materials so that further developments in materials design and synthesis,and device engineering can be more efficient and objective.     

ORDERING TRANSFORMATION OF γ TO γ1 IN TiAl+Nb SYSTEM

A series of TiAl+Nb alloys with various Nb contents has been employed to explore phase relationship and the evolution of microstructure.A new ordered γ derivative (γ₁) has been observed in the alloy containing 20 at% Nb.The additional diffraction spots added to the diffraction pattern of L1₀ (TiAl) structure have been found in the alloy containing Nb up to 11 at% in terms of further ordering.The transformation from L1₀ (TiAl) structure to the further ordering phase,γ₁,is a continuous ordering process with the substitution of Nb atoms for Ti atoms in alloys with over-stoichiometric Al content of TiAl.The possible transformtion characterzation has been discussed.     

Electronic Properties of Organic Semiconductors Based on Nonconjugated Polymers

1 Results The paper presented review of experimental results on the charge transport study in the polymer materials,possessed charge instability.The base of these materials is noncojugated polyaromatic compounds.Characteristic feature these materials is a wide of band gap up to 4.3 eV and the value of first ionization potential about 6 eV.Electronic energetic parameters like these are typical for insulator materials.However it was established that there are not only hopping mechanism of charge transport possible but coherent too in such organic systems.Wide band gap organic material capable to transport charge carrier effectively under certain conditions and the same time conductivity can reach 105 (Ohm·cm)-1 value and current density up to 106 A/cm2 and more.Transformation to conducting phase may occur with different fields and influences,such as electric field,magnet field,pressure,temperature and others.These transformations are reversible as a rule.There is three main of the phenomena fields may be emphasize: electro-optical,switching,and electronic phenomena,including nanophenomena.Electro-optical phenomena are electroluminescence first of all[1].Switching phenomena unites as following switching induced by electric field[2],pressure[3],magnet field[4],boundary condition changing[5],traps thermoionization[6],particle irradiation[7].Electronic phenomena which can observe in thin polyarylide films are as follow electron cold emission[8],superconductivity[9],charged induced nanomemory[10],quantum dot generation[11].     

Preparation of ultrahigh surface area porous carbons templated using zeolite 13X for enhanced hydrogen storage

In this report,the use of zeolite 13X as a template to generate ultrahigh surface area carbons,via a two-step process combining liquid impregnation and chemical vapour deposition is explored.The first step in the nanocasting process involves impregnation of zeolite 13X with furfuryl alcohol and the second step consists of chemical vapour deposition(CVD) of ethylene at 700 1C.Zeolite-like structural ordering was achieved for zeolite templated carbons(ZTCs) prepared at variable heating ramp rates of 5,10 or 15 1C/min.The textural properties of ZTCs prepared at all heating ramp rates were comparable with small variations in which the lowest ramp rate(5 1C/min) generated ZTC with highest surface area and pore volume of 3332 m 2 /g and 1.66 cm 3 /g respectively.The carbon materials achieved a remarkable hydrogen uptake of 7.3 wt% at 20 bar and 77 K which is the highest ever recorded for carbon materials.This report also explores the mechanical stability of the ZTCs via compaction at up to 10t(equivalent to 740 MPa) in which the compacted samples showed minimal modification and retained high hydrogen storage capacity.     

Comparison of α particle detectors based on single-crystal diamond films grown in two types of gas atmospheres by microwave plasma-assisted chemical vapor deposition

Chemical vapor deposition(CVD)-grown diamond films have been developed as irradiation-resistant materials to replace or upgrade current detectors for use in extreme radiation environments. However, their sensitivity in practical applications has been inhibited by space charge stability issues caused by defects and impurities in pure diamond crystal materials. In this study, two high-quality CVD-grown single-crystal diamond(SCD) detectors with low content of nitrogen impurities were fabricated and characterized. The intrinsic properties of the SCD samples were characterized using Raman spectroscopy, stereomicroscopy, and X-ray diffraction with the rocking curve mode, cathode luminescence(CL), and infrared and ultraviolet-visible-near infrared spectroscopies. After packaging the detectors, the dark current and energy resolution under α particle irradiation were investigated. Dark currents of less than 5 pA at 100 V were obtained after annealing the electrodes, which is comparable with the optimal value previously reported. The detector that uses a diamond film with higher nitrogen content showed poor energy resolution, whereas the detector with more dislocations showed poor charge collection efficiency(CCE). This demonstrates that the nitrogen content in diamond has a significant effect on the energy resolution of detectors, while the dislocations in diamond largely contribute to the poor CCE of detectors.     

Charge carrier photogeneration in conjugated polymer PhPPV/R6G composite system

Photoconducting organic materials including conju-gated polymers[1―3], organic molecules[4,5], stacked disco- stic liquid crystals[6,7] and self-assembling organic semi-conductors[8,9] have attracted intense interests due to their extraordinary performances. Their charge carrier photo-generation mechanism has been one of the most important subjects of large amounts of publications in view of possi-ble applications in electronic devices such as photovoltaic cells[10―19]. The charge carrier ph…     

Investigation on the electrochemical activation process of Li1.20Ni 0.32Co0.004Mn0.476O2

The lithium-rich layered oxides are one of the most attractive cathode materials for lithium-ion batteries.Here,two types of Li1.20Ni0.32Co0.004Mn0.476O2 were synthesized using Li2CO3 and LiOH as lithium sources.An electrochemical activation process occurs in Li1.2Ni0.32Co0.004Mn0.476O2 prepared from Li2CO3(LLO-1),while no obvious activation in Li1.2Ni0.32Co0.004Mn0.476O2 prepared from LiOH(LLO-2) is observed.Via advanced scanning transmission electron microscopy(STEM),we found that Li2MnO3-like structure is rich in the surface region of LLO-2.The study provides a direct explanation for the electrochemical activation of lithium-rich materials.The sample with more LiMO2-like phase at the surface region shows a better cycling performance.It is likely that more LiMO2-like phase at the surface region could stabilize the interface and improve the cycling performance of the Li-rich cathode materials.     

Performance of a combined capacitor based on ultrafine nickel oxide/carbon nanotubes composite electrodes

A new sol-gel process for the preparation of ultrafine nickel hydroxide electrode materials was developed. The composite electrodes consisting of carbon nanotubes and Ni(OH)₂ were developed by mixing the hydroxide and carbon nanotubes together in different mass ratios. In order to enhance energy density, a combined type pseudocapacitor/electric double layer capacitor was considered and its electrochemical properties were characterized by cyclic voltammetry and dc charge/discharge test. The combined capacitor shows excellent capacitor behavior with an operating voltage up to 1.6 V in KOH aqueous electrolyte. Stable charge/discharge behaviors were observed with much higher specific capacitance values of 24 F/g compared with that of EDLC (12F/g) by introducing 60% Ni(OH)₂ in the anode material. By using the modified anode of a Ni(OH)₂/carbon nanotubes composite electrode, the specific capacitance of the cell was less sensitive to discharge current density compared with that of the capacitor employing pure nickel hydroxide as anode. The combined capacitor in this study exhibits high energy density and stable power characteristics.     

Bipolar charge transport property of N,N′-dicarbazolyl-1,4-dimethene-benzene: A study of the short range order model

Short range order model is commonly used to explain the charge transport property of disordered organic semiconductors.However,its validity is not yet studied.In this paper,the hole and electron mobilities of a bipolar material,N,N’-dicarbazolyl-1,4dimethene-benzene(DCB),were measured through time of flight method.The hole and electron mobilities of DCB based on the crystalline structure were calculated.In order to investigate the short range order model,the ratios of charge mobilities at zero electric field of holes to electrons were calculated.The results showed that this model cannot fully explain our case.The reason was discussed in detail,and a correction method was proposed.We showed that using the short range order model without preconditions to explain the charge transport property of amorphous materials may lead to deviations,which is often neglected in the past.     

Charge Transfer and Bonding Strength in Lithium-intercalated Polyaromatic Hydrocarbons Studied by Photoelectron Spectroscopy

1 Results The potential applications of small-, medium-and large-size polyaromatic hydrocarbons for charge and energy storage in lithium metal and lithium ion batteries are discussed. In order to find the best carbon-based electrode materials, the specific roles of the molecular and solid-state contributions have to be understood. For the molecular contributions, a semi-quantitative method is proposed to compare the charge storage capability of polyaromatic hydrocarbon molecules. A compilation of results for oligophenyls, oligoacenes and medium-size planar systems suggest trends in the dependence of the charge storage capability on the size and shape of the molecules[1].     

Influence of InAs deposition thickness on the structural and optical properties of InAs quantum wires

The influence of InAs deposition thickness on the structural and optical properties of InAs/InA1As quantum wires (QWR) superlattices (SLS) was studied. The transmission electron microscopy (TEM) results show that with increasing the InAs deposited thickness, the size uniformity and spatial ordering of InAs QWR SLS was greatly improved, but threading dislocations initiated from InAs nanowires for the sample with 6 monolayers (MLs) InAs deposition. In addition, the zig-zag features along the extending direction and lateral interlink of InAs nanowires were also observed. The InAs nanowires, especially for the first period, were laterally compact. These structural features may result in easy tunneling and coupling of charge carders between InAs nanowires and will hamper their device applications to some extent. Some suggestions are put forward for further improving the uniformity of the stacked InAs QWRs, and for suppressing the formation of the threading dislocations in InAs QWR SLS.     

Electrochemical preparation and abnormal infrared effects of nanostructured Ni thin film

Nanometer-scale thin film of Ni supported on glassy carbon (nm-Ni/GC) was prepared by electrochemical deposition through cyclic voltammetry (CV). The properties of nm-Ni/GC were studied by electrochemical in situ FTIR reflection spectroscopy using CO adsorption as probe reaction. It has revealed that the nm-Ni/GC exhibits almormal infrared effects (AIREs). The study has extended the inves-tigation of the AIREs that we have discovered initially on nanostructured film materials of platinum group metals and alloys to nanostructured film materials of iron group metals.     

Guide for Authors

<正>The journal of"Progress in Natural Science:Materials International(PROG NAT SCI-MATER)"sponsored and organized by both Chinese Materials Research Society(C-MRS)and International Union of Materials Research Societies(IUMRS)publish its first issue in November,2010.The journal reports the recent research results in the field of material science and technology,mainly covering the new materials and technologies in some key areas,such as,energy and environmental materials,advanced structural materials,