Search

Adsorptive separation is an appealing technology for propylene and propane separation; however, the challenge lies in the design of efficient adsorbents which can distinguish the two molecules having very similar properties. Here we report a kinetically amplified separation by creating wiggling mesopores in structurally robust carbon monoliths. The wiggling mesopores with alternating wide and narrow segments afford a surface area of 413 m2 g-1 and a tri-modal pore size distribution centered at 1.5, 4.2 and 6.6 nm, respectively. The synergistically kinetic and equilibrium effects were observed and quantitatively assessed, which together ensured a remarkable propylene/propane selectivity up to 39. This selectivity outperformed not only the available carbon adsorbents but also highly competitive among the dominated crystalline porous adsorbents. In addition, the wiggling mesoporous carbon adsorbent showed excellent dynamical separation stability, which ensured its great potential in practical molecular separations.

Confined nanospace pyrolysis (CNP) has attracted increasing attention as a general strategy to prepare task-specific hollow structured porous carbons (HSPCs) in the past decade. The unique advantages of the CNP strategy include its outstanding ability in control of the monodispersity, porosity and internal cavity of HSPCs. As a consequence, the obtained HSPCs perform exceptionally well in applications where a high dispersibility and tailored cavity are particularly required, such as drug delivery, energy storage, catalysis and so on. In this review, the fundamentals of the CNP strategy and its advances in structural alternation is first summarized, then typical applications are discussed by exemplifying specific synthesis examples. In addition, this review offers insights into future developments for advanced task-specific hollow structured porous materials prepared by the CNP strategy.

Assembly of the top-down graphene units mostly results in 3D porous structure with randomly organized pores. The direct bottom-up synthesis of macroscopic 2D graphene sheets with organized pores are long sought in materials chemistry field, but rarely achieved. Herein, we present a self-catalysis-assisted bottom-up route using L-glutamic acid and iron chloride as starting materials for the fabrication of the millimeter-sized few-layer graphene sheets with aligned porous channels parallel to the 2D direction. The amino- and carboxyl-functional groups in L-glutamic acid can coordinate with iron cations, thus allowing an atomic dispersion of iron cations. The pyrolysis thus initiated the growth of graphene catalyzed by in-situ generated iron nanoparticles, and a dynamic flow of iron nanoparticles eventually led to the formation of millimeter-sized few-layer graphene sheets with aligned channels (60–85 nm in diameter). Used as anodes in lithium-ion batteries, these graphene sheets showed a good rate capability (142 mA h g−1 at 2 A g−1) and high capacity retention of 93% at 2 A g−1 after 1200 cycles. Kinetic analysis revealed that lithium ions storage was dominated by diffusion behavior and capacitive behavior together, in that graphene sheets with aligned channels could accelerate electron transfer and shorten lithium ions transport pathway. This work provides a novel approach to prepare unique porous graphene materials with specific structure for energy storage.

There is growing evidence that pillaring up a densely packed ultramicroporous two-dimensional (2D) structure is an effective strategy to reduce their internal diffusion. Reliable pillaring paradigms, however, is rather challenging. Here we report a one-pot multi-component sequential assembly method for the preparation of a new self-pillared 2D polymer and ultramicroporous carbon with integrated surface protrusions. The molecular level pillaring process is surprisingly fast, that is, in 10 min. The thickness of nanoplate edge and the density (roughness), angle as well as height of protrusions can be precisely tuned. Exemplified in coal bed methane purification/separation, this unique pillared 2D carbons exhibit a CH4 /N2 selectivity up to 24 at a low CH4 partial pressure and two orders of magnitude faster CH4 diffusion kinetics than the commercial carbon molecular sieves. This solution synthesis methodology is generalizable for creation and fine tuning of pillared 2D heterostructures.

Electrochemically catalytic conversions have attracted worldwide interest as promising routes to reach a sustainable and green energy cycle. The exploration of efficient electrocatalysts is one of the key tasks, in which the majority has focused on devising new active centers; however, mass transport that determines the reactant supply and the conductance of electrolyte ions and electrons is often overlooked. Here, we report on spatially locating active centers into parallelly bimodal mesopores by precisely engineering mesopore geometries, through which the contribution of the paralleled transport channels to the activity of gas-consuming reactions was quantitatively determined. Under identical conditions, bimodal mesoporous carbon-based electrocatalysts displayed a 2.9 times higher CO partial current density than monomodal mesoporous catalysts for CO2-to-CO conversion in the kinetic region of −1.1 V vs. RHE. Likewise, the strong correlation between the activity enhancement and the bimodal mesopore geometry was verified for supported molecular catalysts and applicable to other gas-consuming reactions such as the O2 reduction reaction. These encouraging results offer a fresh and general idea to advance electrocatalysts by pore geometry engineering on the mesoscale.

For the design of atom-precise copper nanoclusters, besides the exploration of their aesthetic cage-like architectures, their structural modulation and potential applications are being extensively explored. Herein, an atom-precise 20-core copper(I)-alkynyl nanocluster (UJN-Cu20) protected by ethinyloestradiol ligands issynthesized. By virtue of outer-shell hydroxyl groups, UJN-Cu20 could be uniformly modified on the surface of TiO2 nanosheets via hydrogen bonding interactions, thus forming an efficient nanocomposite photocatalyst for hydrogen evolution. By constructing a Z-scheme heterojunction, the photocatalytic hydrogen evolution activity of the nanocomposite (13 mmol g−1 h−1) significantly improved as compared to that of TiO2 nanosheets (0.4 mmol g−1 h−1). As a narrow bandgap cocatalyst, UJN-Cu20 is confirmed to effectively inhibit the electron–hole recombination on the surface of the TiO2 nanosheet, which provides a new concept for the design of copper cluster-assisted effective photocatalysts.

Clays and micas are receiving attention as materials that, in their atomically thin form, could allow for novel proton conductive, ion selective, osmotic power generation, or solvent filtration membranes. The interest arises from the possibility of controlling their properties by exchanging ions in the crystal lattice. However, the ion exchange process itself remains largely unexplored in atomically thin materials. Here we use atomic-resolution scanning transmission electron microscopy to study the dynamics of the process and reveal the binding sites of individual ions in atomically thin and artificially restacked clays and micas. Imaging ion exchange after different exposure time and for different crystal thicknesses, we find that the ion diffusion constant, D, for the interlayer space of atomically thin samples is up to 10^4 times larger than in bulk crystals and approaches its value in free water. Surprisingly, samples where no bulk exchange is expected display fast exchange if the mica layers are twisted and restacked; but in this case, the exchanged ions arrange in islands controlled by the moir\'e superlattice dimensions. We attribute the fast ion diffusion to enhanced interlayer expandability resulting from weaker interlayer binding forces in both atomically thin and restacked materials. Finally, we demonstrate images of individual surface cations for these materials, which had remained elusive in previous studies. This work provides atomic scale insights into ion diffusion in highly confined spaces and suggests strategies to design novel exfoliated clays membranes., Comment: 11 pages, 4 figures, plus 35 pages supplementary information

A new asymmetric capacitor concept is proposed providing high energy storage capacity for only one charging direction. Size‐selective microporous carbons (w2 nm), gives access to both ions. This architecture exclusively charges in one direction with high rectification ratios (RR=12), representing a novel capacitive analogue of semiconductor‐based diodes (“CAPode”). By precise pore size control of microporous carbons (0.6 nm, 0.8 nm and 1.0 nm) combined with an ordered mesoporous counter electrode (CMK‐3, 4.8 nm) electrolyte cation sieving and unidirectional charging is demonstrated by analyzing the device charge‐discharge response and monitoring individual electrodes of the device via in situ NMR spectroscopy.

Background Though titanium (Ti) is widely used as dental materials in the clinic, effective methods to treat Ti for higher surface biological activity still lack. Through Surface mechanical attrition treatment (SMAT) technology we could endow Ti with gradient nanostructured surface (GNS Ti). To investigate the biocompatibility of GNS Ti for its further application in dental implant field, we study the effects of GNS Ti on cell responses in vitro and osseointegration of the implant with surrounding bone tissues in vivo. Methods In this study, GNS Ti was fabricated by SMAT. In vitro experiment, we co-cultured GNS Ti with bone mesenchymal stem cells (BMSCs), surface characterization was detected by transmission electron microscope (TEM). Adhesion, proliferation and differentiation of BMSCs were evaluated by scanning electron microscope (SEM), MTT, flow cytometry (FCM), alkaline phosphatase (ALP) and osteocalcin (OCN) tests. In vivo experiment, the GNS Ti was implanted into the rabbit mandible. Osteogenesis and osseointegration were evaluated by Micro CT, toluidine blue staining, and immunohistochemical staining at 4, 8, and 12 weeks postoperatively. Results Both results showed that compared with the coarse grained (CG) Ti, the GNS Ti stimulated the adhesion, proliferation, and differentiation of BMSCs and improved osteogenesis and osseointegration. Conclusions This study indicates that gradient nanostructured Ti is a promising material for dental implant application.

In order to add safely external electric fields into the systems of the explosives with strong cage strain, the effects of the external electric fields on the strengths of trigger linkages, cage strain energies (CSEs), surface electrostatic potentials (ESPs), as well as impact and shock initiation sensitivities of CL-20 were investigated using the B3LYP and M06–2X methods with 6–311++G(2d,p) basis set. The results show that the changes of the strengths of the N–NO2 bonds are more notable than those of the bonds forming cage, and the changes involving the N–NO2 bonds attached to the five-membered ring are more significant than those attached to the six-membered ring. In most cases, the CSEs in the electric fields are stronger than those in no field. From the BDEs, the N–NO2 cleavage is the decomposition reaction pathway in detonation initiation. However, from the surface ESPs, the N–NO2 cleavage, C–N and C–C bond breaking may initiate the reactions. The global ESPs are more reasonable and reliable to estimate the impact sensitivities of the cage-shaped explosives. The changes of the bond lengths, Mulliken bond orders, nitro group charges and BDEs correlate well with the external electric field strengths. Interestingly, an abnormal result is found that the h50 values in the electric fields are larger than those in no field.

Defect-free graphene is impermeable to gases and liquids but highly permeable to thermal protons. Atomic-scale defects such as vacancies, grain boundaries, and Stone-Wales defects are predicted to enhance graphene's proton permeability and may even allow small ions through, whereas larger species such as gas molecules should remain blocked. These expectations have so far remained untested in experiment. Here, we show that atomically thin carbon films with a high density of atomic-scale defects continue blocking all molecular transport, but their proton permeability becomes similar to 1000 times higher than that of defect-free graphene. Lithium ions can also permeate through such disordered graphene. The enhanced proton and ion permeability is attributed to a high density of eight-carbon-atom rings. The latter pose approximately twice lower energy barriers for incoming protons compared to that of the six-atom rings of graphene and a relatively low barrier of similar to 0.6 eV for Li ions. Our findings suggest that disordered graphene could be of interest as membranes and protective barriers in various Li-ion and hydrogen technologies.

A novel carbon material with an ultra-hydrophilic surface and an ordered arrangement of uniformly sized mesopores is synthesized via a solvent-free nanocasting approach conducted in a planetary ball mill. The synthesis involves a mechanochemical coordination reaction of bipyridine and copper chloride and its subsequent carbonization. Stemming from the synergistic effect of uniformly dispersed 34 wt% of heteroatoms and the highly ordered mesoporous structure (specific surface area >1000 m2 g−1, pore volume >1.2 cm3 g−1), the apparent water contact angle of the material is 0° – an unprecedented value for carbon materials. This novel type of carbon, with its tailorable pore structure, constitutes an ideal model material for fundamental investigations and can open new perspectives for advanced applications of porous carbons where polar wettability is crucial. Moreover, the solvent-free ball milling synthesis concept paves the way towards many novel materials, that syntheses are currently suffering from solubility issues in the nanocasting process.

Li–O2 batteries trigger worldwide interest as promising candidates for future energy supplies. One of the major challenges regarding current Li–O2 batteries is exploring highly efficient cathodes with sophisticated structures and compositions. Herein, highly dispersed metal (Pd) or oxide (RuO2) nanoparticles on ultra-polar carbon are synthesized and employed as cathode materials for Li–O2 batteries. The hierarchically porous structure of the carbon facilitates the oxygen diffusion and electrolyte impregnation and provides enough space to accommodate the discharge products. More importantly, the porous carbon with the ultra-polar surface serves as an efficient support for distinct dispersion of Pd or RuO2 nanoparticles which not only greatly enhances the catalytic activity but also eases side reactions by passivating the carbon defects. By virtue of the hierarchical structure associated with the extremely high dispersion of active particles, the battery performance is effectively enhanced by greatly prolonging the cycle life and significantly lowering the overvoltages especially for the charging process. The encouraging results suggest that such ultra-polar hierarchical carbon-based composites can be appealing materials for rechargeable Li–O2 batteries.

Defect-free monolayers of graphene and hexagonal boron nitride are surprisingly permeable to thermal protons, despite being completely impenetrable to all gases. It remains untested whether small ions can permeate through the two-dimensional crystals. Here we show that mechanically exfoliated graphene and hexagonal boron nitride exhibit perfect Nernst selectivity such that only protons can permeate through, with no detectable flow of counterions. In the experiments, we use suspended monolayers that have few, if any, atomic-scale defects, as shown by gas permeation tests, and place them to separate reservoirs filled with hydrochloric acid solutions. Protons account for all the electrical current and chloride ions are blocked. This result corroborates the previous conclusion that thermal protons can pierce defect-free two-dimensional crystals. Besides the importance for theoretical developments, our results are also of interest for research on various separation technologies based on two-dimensional materials., Defect-free monolayers of graphene and hexagonal boron nitride are highly permeable to thermal protons, but are impenetrable to gases. Here the authors show that mechanically exfoliated crystals exhibit perfect proton selectivity, corroborating proton transport through the bulk without atomic-scale defects.

Monolayers of graphene and hexagonal boron nitride (hBN) are highly permeable to thermal protons1,2. For thicker two-dimensional (2D) materials, proton conductivity diminishes exponentially, so that, for example, monolayer MoS2 that is just three atoms thick is completely impermeable to protons1. This seemed to suggest that only one-atom-thick crystals could be used as proton-conducting membranes. Here, we show that few-layer micas that are rather thick on the atomic scale become excellent proton conductors if native cations are ion-exchanged for protons. Their areal conductivity exceeds that of graphene and hBN by one to two orders of magnitude. Importantly, ion-exchanged 2D micas exhibit this high conductivity inside the infamous gap for proton-conducting materials3, which extends from ∼100 °C to 500 °C. Areal conductivity of proton-exchanged monolayer micas can reach above 100 S cm−2 at 500 °C, well above the current requirements for the industry roadmap4. We attribute the fast proton permeation to ~5-A-wide tubular channels that perforate micas’ crystal structure, which, after ion exchange, contain only hydroxyl groups inside. Our work indicates that there could be other 2D crystals5 with similar nanometre-scale channels, which could help close the materials gap in proton-conducting applications. Few-layer micas show proton permeation across the sheet, exceeding that of graphene and hBN by one to two orders of magnitude.

We propose an effective strategy to engineer a unique kind of porous carbon cuboid with tightly anchored cobalt/cobalt oxide nanoparticles (PCC–CoOx) that exhibit outstanding electrochemical performance for many key aspects of lithium-ion battery electrodes. The host carbon cuboid features an ultra-polar surface reflected by its high hydrophilicity and rich surface defects due to high heteroatom doping (N-/O-doping both higher than 10 atom%) as well as hierarchical pore systems. We loaded the porous carbon cuboid with cobalt/cobalt oxide nanoparticles through an impregnation process followed by calcination treatment. The resulting PCC–CoOx anode exhibits superior rate capability (195 mA h g−1 at 20 A g−1) and excellent cycling stability (580 mA h g−1 after 2000 cycles at 1 A g−1 with only 0.0067% capacity loss per cycle). Impressively, even after an ultra-long cycle life exceeding 10000 cycles at 5 A g−1, the battery can recover to 1050 mA h g−1 at 0.1 A g−1, perhaps the best performance demonstrated so far for lithium storage in cobalt oxide-based electrodes. This study provides a new perspective to engineer long-life, high-power metal oxide-based electrodes for lithium-ion batteries through controlling the surface chemistry of carbon host materials.

Exploring the role of surface hydrophilicity of non-precious metal N-doped carbon electrocatalysts in electrocatalysis is challenging. Herein we discover an ultra-hydrophilic non-precious carbon electrocatalyst, showing enhanced catalysis efficiency on both gravimetric and areal basis for oxygen reduction reaction due to a high dispersion of active centres.

There is significant interest in high-performance materials that can directly and efficiently capture water vapor, particularly from air. Herein, we report a class of novel porous carbon cuboids with unusual ultra-hydrophilic properties, over which the synergistic effects between surface heterogeneity and micropore architecture is maximized, leading to the best atmospheric water-capture performance among porous carbons to date, with a water capacity of up to 9.82 mmol g(-1) at P/P0 =0.2 and 25 °C (20% relative humidity or 6000 ppm). Benefiting from properties, such as defined morphology, narrow pore size distribution, and high heterogeneity, this series of functional carbons may serve as model materials for fundamental research on carbon chemistry and the advance of new types of materials for water-vapor capture as well as other applications requiring combined highly hydrophilic surface chemistry, developed hierarchical porosity, and excellent stability.

This chapter introduces a wide range of designed polybenzoxazine-based polymers as unique precursors for functional nanoporous carbons preparation, starting with morphology-controllable polybenzoxazines and their carbon counterparts with intriguing structures, then to composition-tuned polybenzoxazines and related composites, and then derived multiheteroatom-doped nanoporous carbons. In particular, the design principle and key structural features of polybenzoxazine polymers and their derived carbon products are highlighted. In the end, a summary and perspective are given.

Silicon is an important material for technical applications. Recently, a long-puzzling metastable phase of silicon (T12-Si) has been theoretically identified. In this work, we used first-principles calculations to study the electronic and elastic properties and the hardness of this new silicon allotrope to enrich the relevant information. These properties of cubic Si (c-Si) were also calculated for comparison. The results show that the T12-Si is mechanically anisotropic and has a lower bulk modulus and shear modulus than c-Si. Its theoretical hardness is 10.3 GPa, smaller than the value of 13.5 GPa for c-Si. Analyses of the electronic properties reveal that T12-Si is an indirect band gap crystal with a gap value of 0.69 eV, making it a promising semiconductor for future technical applications and that covalent sp 3-hybridization is the main interaction in this crystal. The reason the calculated hardnesses of c-Si and T12-Si are rather small compared to that of diamond is also discussed.

In order to improve the cooling effect of cable ultraviolet cross-linking irradiation box, the structure of spreader plate, reflector and outlet were improved. Then the 3D solid model of the irradiation box was established and the numerical simulation of turbulent flow field was performed due to the principle of Computational Fluid Dynamics (CFD). On this basis, the flow fields characteristics inside the irradiation box of original and improve programs were analyzed. The results showed that volume air flow of the new program increased by 36.6% and air velocity around the mercury lamp and XLPE cable surface was increased, so the better cooling effect can be achieved in the new program.

Sandwich-type microporous hybrid carbon nanosheets (MHCN) consisting of graphene and microporous carbon layers are fabricated using graphene oxides as shape-directing agent and the in-situ formed poly(benzoxazineco -resol) as carbon precursor. The reaction and condensation can be readily completed within 45 min. The obtained MHCN has a high density of accessible micropores that reside in the porous carbon with controlled thickness (e.g., 17 nm), a high surface area of 1293 m 2 g − 1 and a narrow pore size distribution of ca. 0.8 nm. These features allow an easy access, a rapid diffusion and a high loading of charged ions, which outperform the diffusion rate in bulk carbon and are highly effi cient for an increased double-layer capacitance. Meanwhile, the uniform graphene percolating in the interconnected MHCN forms the bulk conductive networks and their electrical conductivity can be up to 120 S m − 1 at the graphene percolation threshold of 2.0 wt.%. The bestpractice two-electrode test demonstrates that the MHCN show a gravimetric capacitance of high up to 103 F g − 1 and a good energy density of ca. 22.4 Wh kg − 1 at a high current density of 5 A g − 1 . These advanced properties ensure the MHCN a great promise as an electrode material for supercapacitors.

Gypsum-based composites was produced using gypsum power(cement), PVA, white latex and sawdust via pouring process. The influences of water/ cement ratio, PVA/ cement ratio and glue/ cement ratio on release time, density and impact strength of the gypsum-based composites were investigated through orthogonal experiment. The results showed that PVA strengthened obviously impact strength, and also delayed the s release time of the Gypsum-based composites. Sawdust as light filler reduced the composites density. Low content of white latex is beneficial to increase the impact strength, while high content of white latex is easy to form micelle in the gypsum crystallization process and is enclosed in crystals, which decreases the impact strength of composite materials.

Hierarchically porous carbons with variable pore sizes at multi-length-scale, a nitrogen and boron co-doped and local graphitized framework, and high mechanical strength were synthesized through the self-assembly of poly(benzoxazine-co-resol) with ionic liquid C16mimBF4 and a carbonization process. In this synthesis, the ionic liquid acts both as a structure directing agent and a heteroatom precursor. The obtained porous carbons have a specific surface area lower than 376 m2 g−1 and thus a high skeleton density. With such heteroatom doped skeleton structures and fully interconnected macropores, mesopores and micropores, the hierarchically porous carbon shows outstanding electrochemical performance, e.g. a superior high gravimetric capacitance (Cg) of 247 F g−1, an interfacial capacitance (CS) of 66 μF cm−2 (calculated based on the discharge curve with a constant current density of 0.5 A g−1), whilst a high volumetric capacitance (Cv) of 101 F cm−3 compared to those reported in the literature. Cycling stability tests indicate that the carbon exhibits a capacitance retention of ∼96.2% after 4000 charge–discharge cycles, strongly reflecting an excellent long-term cyclability of the electrode. Due to its unique skeleton structure and high conductivity, such hierarchically porous carbon shows promise as an electrode material for supercapacitors.

In this contribution, we report a general surface engineering strategy to transform nonpolar nanocarbons (e.g., carbon nanotube and graphene) into amphiphilic nanocarbons with unique ultrahydrophilic@ultrahydrophobic surface configuration and hierarchical structure by grafting a thin layer of metal-organic frameworks followed by pyrolysis and leaching. The outer ultrahydrophilic carbon layer features rich surface heterogeneity (B-/N-doping both up to ca. 10 at. %) and high density of microporosity, while the inner nonpolar CNT or graphene provides a high electronic conductivity. The unique bipolar surface and high heterogeneity as well as highly accessible hierarchical structures render this family of nanocarbons capable of a high surface efficiency under both aqueous and organic conditions, as it is reflected in the behavior of the electrodes for supercapacitors by comparing a wide range of highly porous nonpolar carbons. The bipolar hierarchical carbons' efficiency in terms of areal capacitance and energy density are 3-6 times and 2-3 times higher than that of typical benchmark materials (e.g., commercially popular YP-50F carbons, CNT, and graphene etc.). More importantly, the study of this series of model carbon materials may help researchers to understand in-depth how carbon surface chemistry with a high density of doping sites influences the wetting, transport, and electrosorption behavior of charged ions in aqueous and organic conditions.

Silicon was selectively removed from a silicon carbonitride (SiCN) aerogel by hot chlorine gas treatment, leading to a N-doped carbon aerogel (N-CDC aerogel). The combined effects of pyrolysis and etching temperature were studied with regard to the change in the composition of the material after etching as well as the microstructure of the produced hierarchically porous material. Upon removal of Si from amorphous SiCN, carbon and nitrogen, which are not bonded together in the starting material, react, creating new C–N bonds. The removal of silicon also gives rise to a high amount of micropores and hence a high specific surface area, which can be beneficial for the functionality of the carbonaceous material produced. The mesoporous structure of the aerogel allows us to complete the etching at low temperature, which was found to be a crucial parameter to maintain a high amount of nitrogen in the material. The combination of a high amount of micropores and the mesopore transport system is beneficial for adsorption processes due to the combination of a high amount of adsorption sites and effective transport properties of the material. The N-CDC aerogels were characterized by nitrogen physisorption, X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG/DTA), and infrared spectroscopy (DRIFT) and they were evaluated as CO2 absorbers and as electrodes for electric double-layer capacitors (EDLCs).

This work aims to optimize the structural features of hierarchical porous carbon monolith (HCM) by incorporating the advantages of metal–organic frameworks (MOFs) (Cu3(BTC)2) to maximize the volumetric based CO2 capture capability (CO2 capacity in cm3 per cm3 adsorbent), which is seriously required for the practical application of CO2 capture. The monolithic HCM was used as a matrix, in which Cu3(BTC)2 was in situ synthesized, to form HCM-Cu3(BTC)2 composites by a step-by-step impregnation and crystallization method. The resulted HCM-Cu3(BTC)2 composites, which retain the monolithic shape and exhibit unique hybrid structure features of both HCM and Cu3(BTC)2, show high CO2 uptake of 22.7 cm3 cm–3 on a volumetric basis. This value is nearly as twice as the uptake of original HCM. The dynamic gas separation measurement of HCM-Cu3(BTC)2, using 16% (v/v) CO2 in N2 as feedstock, illustrates that CO2 can be easily separated from N2 under the ambient conditions and achieves a high separation factor for CO2 over ...

Experiment on bearing capacity of 24 Q460 high strength angle steel for compression members attached by one leg shows: the ultimate bearing capacity of the experiment value are higher than the calculated of the “Design of Latticed Steel Transmission Structures” (ASCE10-1997), on the same section in different slenderness ratio of components, the larger slenderness ratio, the higher the ratio; while on the same slenderness ratio in different sections, the greater width-thickness radio, the greater the ratio. Based on this problem, analyzing the current standard, a set of formulas based on high-strength angle struts connected by single Limb was brought, which can used for the design of the Q460 high-strength angle.

It was performed nonlinear finite element analysis for K-shape eccentrically braced steel frames on link beam. Analysis indicates that the strength, rigidity, ductility and energy-dissipation performance of K shape eccentrically braced steel frames deteriorate differently with the length increase of link beam. The shorter the link beam is, the larger plastic deformation of it, so it makes plastic collapse easily, while a long link beam has a poor cyclic behavior. At the end of this paper, compared with the experimental results show that the finite element method is feasible, the results can provide a reference for the engineering design and related research.

Carbon nitride (CNx) films were fabricated by plasma enhanced chemical vapor deposition technology in methane-ammonia system, in which the plasma was excited by the hollow cathode glow discharge. The composition，microstructure and hardness of the deposited films were investigated by measurements employing X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and nano-indentation experiment. The results indicate that the nitrogen content in the film varies from 4.2 to 8.6 at.% and the nitrogen atoms are bonded to carbon atoms through C-N, C=N and C≡N bonds. Furthmore, higher nitrogen content is in favor of the formation of C-N bond, which may enhance the film hardness.

A series of hierarchically multimodal (micro-, meso-/macro-) porous carbon monoliths with tunable crystallinity and architecture have been designedly prepared through a simple and effective gelation through a dual phase separation process and subsequent pyrolysis. Because of the magnificent structural characteristics, such as highly interconnected three-dimensional (3D) crystalline carbon framework with hierarchical pore channels, which ensure a fast electron transfer network and lithium-ion transport, the carbon anodes exhibit a good cycle performance and rate capability in lithium-ion cells. Importantly, a correlation between the electrochemical performances and their structural features of crystalline and textural parameters has been established for the first time, which may be of valid for better understanding of their rate performance and cycle stability.

At present, according to Code for Design of Steel Structures（GB50017—2003）,for axially loaded column with plated column base, the column bases are considered as hinged supports, but possess actually remarkable rotational restraint. The effective length of columns can be decreased when the constraint function of plated column base is considered in calculation. The calculation of effective length factor of columns is usually according to the approximate formula which is deduced by the rotational stiffness. Axially loaded column plated column base models were established with the finite element software, the effective length factor of columns was obtained by the method which can avoid calculating rotational stiffness of plated column bases, the influence factors on the rotational restraint of axially loaded column plated column base, such as the base plate thickness, the diameter of anchors, the column section size were also analyzed in this paper.

In the paper, the interface crack of rubber - metal ring under the radial displacement load was studied by nonlinear finite element method, changes of the tear energy with crack dimension which extending from extrusion end and tensile end along the axial and circumferential direction to the interface was analyzed. The result is that there is a certain possibility of axial extension in the tensile end. The crack propagation is most likely to occur along the circumferential direction while is impossible along either axial or the circumferential direction in the extrusion end.

Nanocomposites were obtained by mixing elastomeric copolymer and nanoSiO2 in double-screw extruder at 130-150°C, in which the elastomeric copolymer was prepared by copolymerization of poly (methyl methacrylate (PMMA) macromonomer and butyl acrylate (BA) in benzene using azobisisobutyro-nitrile (AIBN) as initiator. The results indicated that increasing the amount of PMMA, the molecular weight of PMMA and copolymers, nanosilica charged resulted in improving the tensile strength and modulus at 300% elongation of nanocomposites, on the contrary, decreasing ultimate elongation and permanent set decrease. In additions, the tensile strength and the modulus at 300% elongation of nanocomposites reached to a maximum while the mass ratio of nanoSiO2 to copolymer was 3%.

Well-aligned crystalline ZnO nanorod arrays were synthesized on the glass substrate via an aqueous solution route, and the effect of the pH value on structural properties and morphology of ZnO nanorod arrays was investigated using XRD and FESEM. FESEM micrographs show the formation of ZnO nanorod arrays at different pH values. XRD patterns confirm that the ZnO nanorods were wurtzite structure preferentially oriented in c-axis direction and the highest quality of nanorod array was formed at high pH value.

We show theoretically that the optical absorption of one-dimensional metallic photonic bandgap (MPBG) materials, which consist of alternating Ag and MgF2 layers, can be substantially enhanced by modifying the structure properly through decreasing the thickness of top MgF2 layer to half and increasing the thickness of bottom Ag layer to fivefold. Using transfer matrix method, absorption spectra and the electric field distribution profiles are numerically calculated. The absorption spectrum under reverse-direction incidence is also investigated. Based on strong and direction-dependent absorption properties, the proposed MPBG structure could allow many potential applications such as unique photothermal absorbing materials.

A series of poly(trimethylene terephthalate)/maleinized poly(octene-ethylene) copolymer blends are prepared and their melting, crystallization and dynamic mechanical propwerties were studied by using differential scanning calorimetry (DSC) and dynamic mechanical analyzer (DMA) respectively. The results suggest that the glass transition temperature of the blends shift to higher temperature because of the interaction between PTT and POE components. POE-MAH serves as a nucleating agent for the crystallization of PTT, and it increases the crystallizaiton rate of the blend and the start crystallizaiton temperature, but reduces the degree of crystallinity. Proper content of POE, e.g.1-2%, can improve the elastic modulus of the blend, but too much POE will depress the modulus.

This paper is based on the experiment of Q460 high-strength single-angle equal-leg compression members with a concentric load at one end and normal framing eccentricity at the other end. An experimental program confirmed that the finite element software ANSYS can be used, with a reasonable degree of accuracy, to simulate the experiment and predict the behavior and bearing capacity of single-angle compression members [1]. Then, parametric analysis was done in order to examine the impacts of several factors such as initial bending, Young’s modulus of elasticity and the gusset plate thickness. It was found that initial bending and Young’s modulus of elasticity in the angle section have slight effects on bearing capacity. When the gusset plate thickness to angle width ratio is no more than 0.2, the thickness of plate has less impact on bearing capacity; when the ratio is more than 0.2, the impact increased obviously.

The rapid and scalable synthesis of hierarchical carbon monoliths with an ordered mesostructure and fully interconnected macropores has been demonstrated. Resorcinol and formaldehyde based polymers were used as the carbon precursor, triblock copolymer Pluronic F127 as the structural directing agent, and organic base lysine as both the polymerization catalyst and mesostructure assembly promoter. In the presence of lysine, homogeneous and crack-free polymer monoliths can be obtained through rapid gelation in 15 min at 90 °C. The polymer monoliths have a robust framework, which can be directly dried at 50 °C in air and carbonized at high temperature under a nitrogen atmosphere. The carbon monoliths are crack-free and have an ordered mesostructure with fully interconnected macropores. The surface area and the macropore volume are high with values up to 600 m2 g−1 and 3.52 cm3 g−1, respectively. Further steam activation of the carbon monolith can significantly improve the surface area to 2422 m2 g−1 while still maintaining the ordered mesostructure.

A new class of structural glue called permeant adhesive is introduced for repairing concrete cracks. The viscosity and strength of the permeant adhesive are tested, respectively. Then the durability of concrete such as sulphate attack, freeze-thaw resistance and impermeability of the repaired concrete are discussed. It is shown that temperature and reactive diluent are important factors in viscosity of the permeant adhesive. Curing agent and reactive diluent are important factors in strength. Hereby, the optimum proportion is A: B=1:0.5, and the amount of reactive diluent is 10% to 15%. The strength of the repaired concrete which is immersed in sulphate increases 3% to 26.2%, while the freeze-thaw resistance and impermeability of the repaired concrete are better. The above provide the theoretic and experiment foundation for simpling the pressure grouting technique of the concrete repaired and the application on the permeant adhesive.

Based on the experiment of a one-third scale, single-span, two-storey semi-rigid composite steel frame model with cross-stiffened steel plate shear wall under lateral cyclic loadings, the interactive effect between the joint stiffness and the cross-stiffened steel plate shear wall, the failure mode and energy dissipation mechanism of the structure system were analyzed, some important parameters were obtained in regard to load-carrying capacity, ductility, stiffness and energy dissipation capacity. The results showed that the specimen exhibited excellent ductility, energy dissipation capacity and great safety margin; the stiffness degradation of the joints was not serious, the requirement of ductility was lowered by setting up infill panels, the cooperative work between the frame and the steel plate shear wall was well; stiffeners improved the force condition of steel panels, increased the stiffness and load-carrying capacity of panels, lightened the pinch of hysteretic loops and reduced the noise and tremor of panels. The failure mode of the structure induced by buckling of stiffeners, local buckling and interactive buckling of infill panels，plastic hinges were formed at the bottom of column and semi-rigid connection, the in-plane deformation of specimen was bending failure. The research provides a basis for engineering application and theoretical analysis of the structural system.

A second-order inelastic analysis of semirigid connection steel frame structures is developed. Therein, shearing deformation and axial force simultaneously are considered. A new stability function considered shearing deformation and axial force simultaneously is proposed and the analysis methods for steel structure of semirigid connection based on the structural ultimate bearing capacity are established. The calculatical programe of second-order inelastic analysis semirigid connection steel frame structures is compiled. The numerical examples of steel frames for semirigid connection are analysed using the second-order inelastic analysis in the paper. Load–displacements predicted by the proposed analysis compare well with those given by other approaches. The analysis results show that the proposed method is suitable for adoption in practice.

Poly(ethylene-octene)(POE) and organic montmorillonite(OMMT) acting respectively as the toughening agents and reinforcing agents, were used to prepare nanocomposites with Poly(trimethylene terephthalate)(PTT) in order to modify PTT, and the rheological properties of these composites were investigated by using capillary rheometer instrument. The OMMT used in composite was prepared by intercalating triphenyl phosphate (TPP) into MMT by mixed solution method. PTT/POE/OMMT nanocomposites were prepared by melt blending in twin-screw corotating extruder. Rheological results show that PTT/POE/OMMT composite melt was pseudo-plastic liquid and the pseudo-plasticity of the melt was decreased with increasing OMMT content for the strong interface interactions between OMMT and polymer molecular chains. The melt apparent viscosity was increased with increasing OMMT content. The flow activation energy results suggested that the composite melt having more OMMT components is more sensitive to the change of temperature.

The metal rubber is a kind of material for vibration control. In this paper, experimental research on characteristics of energy dissipation of metal rubber is exploited, and the relation between metal rubber stiffness and the amplitude of relative density and load. The relative between relative density and characteristics of energy dissipation is researched, in the excitation of displacement and load respectively. By comparing variation of the deformation and load with time, we found that the cycle of deformation and load is the same, but the deformation is still lag behind load. The research provided a basis for the application of metal rubber.

Abrasive is the one of key influencing factors during chemical mechanical polishing(CMP) process. Currently, α-Alumina (α-Al2O3) particle, as a kind of abrasive, has been widely used in CMP slurries, but their high hardness and poor dispersion stability often lead to more surface defects. After being polished with composite particles, the surface defects of work pieces decrease obviously. So the composite particles as abrasives in slurry have been paid more attention. In order to reduce defect caused by pure α-Al2O3 abrasive, α-alumina-g-polystyrene sulfonic acid (α-Al2O3-g-PSS) composite abrasive was prepared by surface graft polymerization. The composition, structure and morphology of the product were characterized by Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), time-of-flight secondary ion mass spectroscopy(TOF-SIMS), and scanning electron microscopy(SEM), respectively. The results show that polystyrene sulfonic acid grafts onto α-Al2O3, and has well dispersibility. Then, the chemical mechanical polishing performances of the composite abrasive on glass substrate were investigated with a SPEEDFAM-16B-4M CMP machine. Atomic force microscopy(AFM) images indicate that the average roughness of the polished glass substrate surface can be decreased from 0.835 nm for pure α-Al2O3 abrasive to 0.583 nm for prepared α-Al2O3-g-PSS core-shell abrasive. The research provides a new and effect way to improve the surface qualities during CMP.

A novel α-alumina-g-polyvinylpyrrolidone (α-Al2O3-g-PVP) composite abrasive was prepared by surface grafting polymerization. The chemical mechanical polishing (CMP) performances of the composite abrasive on hard disk substrate were investigated with a UNIPOL-1502 polishing machine. Analyses on the surface of polished substrate indicated that the α-Al2O3-g-PVP composite abrasive exhibited lower surface roughness, less scratch, and improved post-CMP cleaning performances than pure α-alumina abrasive under the same testing conditions.

M M U Rapid Synthesis of Nitrogen-Doped Porous Carbon Monolith for CO2 Capture N IC By Guang-Ping Hao, Wen-Cui Li, Dan Qian, and An-Hui Lu* A T IO N The development of novel materials and new technologies for CO2 capture and storage has gained great attention over the past decades. The necessity for reducing the concentration of CO2 in the atmosphere is a very important issue, since CO2 is considered as a greenhouse gas causing global warming. In addition, higher concentrations of CO2 are toxic for humans, especially in space-limited chambers like submarines and space ships. Traditional technologies for CO2 capture including absorption and adsorption-coupled membrane separation along with the corresponding sorbents such as aqueous amines, microporous coordination polymers (MCPs), zeolitic imidazolate frameworks (ZIFs), different types of nitrogen-doped zeolite, mesoporous silica, and activated carbons have been widely explored. However, MCPs and ZIFs synthesized with nitrogen-containing organic compounds as the crosslinker often suffer from structural instability and inefficiency for CO2 selectivity in the presence of water and thus are limited in their widespread use. For aminemodified solids, the main drawback is the possible loss of ammonia associated with the temperature needed for regeneration and the energy-intensive nature of the regeneration process. For instance, amine-surface-modified or amineimpregnated porous silica (e.g., MCM-41, MCM-48, SBA-15, SBA-16) and zeolite 13X materials fail to capture CO2 effectively, require high temperature and long regeneration times and lack stability over many cycles. It should be pointed out that amine-modified silica-based solids are usually prepared by a post-treatment, which is a time-consuming and costly procedure and often involves the use of toxic and corrosive reagents. Porous carbon materials have many specific features such as high surface area, thermal and chemical stability, and hydrophobic surface properties. The incorporation of basic nitrogen groups into the carbon framework ensures an improved adsorption/absorption for acidic gases. Up to date, porous carbon materials used for CO2 capture were mostly prepared by post-synthetic amine modification or ammonia treatment, which again leads to materials lacking stability and, in addition, the reagents are corrosive, which brings the same disadvantages as for modified silica and zeolites. Alternatively, nitrogencontaining porous carbons can be prepared directly from

The spherulites’ morphology and melting properties of the poly(trimethylene terephthalate) formed in limited space at specific temperatures was studied by the polarized optical microscopy (POM). The results suggest that the spherulites’ morphology depends strongly on the temperature. When the isothermal crystallization temperatures increase from 190 to 225 oC, the spherulites’ morphology continuously changes in the following order: nonbanded → regular banded → serrated banded → nonbanded spherulites. Furthermore, the band spacing increases with the crystallization temperature. Heating the banded spherulites will cause them melt as well as the changing of the bandings, especially the bandings changes in the following order: clear → faint → clear → disappear in a certain range of temperature, which is proposed for resulting from a lamellar melting-recrystallization-remelting mechanism.