Sub-5 nm porous nanocrystals: interfacial site-directed growth on graphene for efficient biocatalysis

The direct production of macromolecular scale (sub-5 nm) porous nanocrystals with high surface area has been a considerable challenge over the past two decades. Here we report an interfacial site-directed capping agent-free growth method to directly produce porous ultrasmall (sub-5 nm), fully crystalline, macromolecular scale nanocrystals. The porous sub-5 nm Prussian blue nanocrystals exhibit uniform sizes (∼4 ± 1 nm), high surface area (∼855 m² g^–1), fast electron transfer (rate constant of ∼9.73 s^–1), and outstanding sustained catalytic activity (more than 450 days). The nanocrystal-based biointerfaces enable unprecedented sub-nanomolar level recognition of hydrogen peroxide (∼0.5 nM limit of detection). This method also paves the way towards the creation of ultrasmall porous nanocrystals for efficient biocatalysis.     

Recycled polypropylene with improved thermal stability and melt processability

Journal of Thermal Analysis and Calorimetry - Polypropylene (PP) is a versatile polymer, with a wide range of applications, from household appliances to packaging and automotive components....     

One-step synthesis of porous PtNiCu trimetallic nanoalloy with enhanced electrocatalytic performance toward methanol oxidation

Pt-based alloy nanoporous structures have attracted a lot of attention because of their high activity and stability toward alcohol oxidation reactions. Especially, Pt alloying with Earth-abundant metal can lower the cost of catalyst. Here, we introduce a one-pot approach to synthesize bimetallic PtCu and Ni-doped PtCu nanoalloy with porous structure. The as-synthesized Ni-doped Pt₆₀Ni₃Cu₃₇ nanoalloys exhibit excellent electrocatalytic properties toward methanol oxidation in acidic medium. The mass activity of the as-synthesized Pt₆₀Ni₃Cu₃₇ nanoalloys is 3.6 times and 5.3 times that of Pt₅₅Cu₄₅ nanoalloys and commercial Pt black for methanol oxidation in 0.2?M methanol solution. Besides, the stability of the as-synthesized Pt₆₀Ni₃Cu₃₇ nanoalloys was much better than Pt₅₅Cu₄₅ nanoalloys and commercial Pt black. After 3600?s chronoamperometry test, the remaining values of the Pt₆₀Ni₃Cu₃₇ nanoalloys are 3.7 times and 11.0 times that of Pt₅₅Cu₄₅ nanoalloys and commercial Pt black. And it is the first time to report that small amount of Ni dopants can boost the activity and stability of PtNiCu alloys toward methanol oxidation.     

Sub-100 nm hollow SnO2@C nanoparticles as anode material for lithium ion batteries and significantly enhanced cycle performances

Rational designing and controlling of nanostructures is a key factor in realizing appropriate properties required for the high-performance energy fields. In the present study, hollow SnO₂@C nanoparticles (NPs) with a mean size of 50 nm have been synthesized in large-scale via a facile hydrothermal approach. The morphology and composition of as-obtained products were studied by various characterized techniques. As an anode material for lithium ion batteries (LIBs), the as-prepared hollow SnO₂@C NPs exhibit significant improvement in cycle performances. The discharge capacity of lithium battery is as high as 370 mAh g^-1, and the current density is 3910 mA g^-1(5 C) after 573 cycles. Furthermore, the capacity recovers up to 1100 mAh g^-1 at the rate performances in which the current density is recovered to 156.4 mA g^-1(0.2 C). Undoubtedly, sub-100 nm SnO₂@C NPs provide significant improvement to the electrochemical performance of LIBs as superior-anode nanomaterials, and this carbon coating strategy can pave the way for developing high-performance LIBs.     

Facile fabrication of a superhydrophobic fabric with mechanical stability and easy-repairability

The poor mechanical stability of superhydrophobic fabrics severely hindered their use in practical applications. Herein, to address this problem, we fabricated a superhydrophobic fabric with both mechanical stability and easy-repairability by a simple method. The mechanical durability of the obtained superhydrophobic fabric was evaluated by finger touching and abrasion with sandpaper. The results show that rough surface textures of the fabric were retained, and the fabric surface still exhibited superhydrophobicity after tests. More importantly, when the fabric lost its superhydrophobicity after a long-time abrasion, it can be easily rendered with superhydrophobicity once more by a regeneration process.     

多级孔IM-5分子筛的简易制备及其在甲烷芳构化中的催化性能

采用一步水热晶化法、不添加第二模板剂、仅通过控制合成条件,制备了具有多级孔道结构的IM-5-H分子筛。多级孔IM-5-H材料展现了与常规IM-5-C分子筛不同的形貌、结构和酸性质。由于IM-5-H分子筛载体介孔结构的促进作用,钼基Mo-IM-5-H催化剂在甲烷无氧芳构化反应中表现出较高的甲烷转化率（13.1%）、芳烃产率（7.5%）和稳定性。该研究为合成多级孔IM-5材料提供了一种简便的方法,同时扩展了微孔-介孔复合材料在甲烷芳构化反应中的应用。     

Preparation,crystal structure and thermal stability of porous lanthanide complexes with 5-methyl isophthalic acid

Three lanthanide complexes 1–3 with 5-methyl isophthalic acid (5-CH₃-H₂bdc) were prepared under hydrothermal conditions, two have formula Eu₂(5-CH₃-bdc)₃(EtOH) (2) and [Er(5-CH₃-bdc)_1.5] · (H₂O) (3) and were characterized by X-ray single crystal diffraction. In 2, there are two europium(III) ions in seven-coordinate pentagonal bipyramid and eight-coordinate bicapped trigonal prism geometries. Complex 2 is a 3-D porous structure with 1-D channels (potential solvent area = 453 ų, 15.7%). One crystallographic independent erbium(III) ion exists and lies in a pentagonal bipyramidal geometry in 3, in which one-dimensional channels are rectangular (potential solvent area = 470 ų, 16.4%). TG-DTG experiments show that these complexes have stability to 750–880°C decomposing to corresponding Ln₂O₃.     

Urease-Dextran complexes with enhanced enzymatic activity and stability

In this study, the urease-dextran non-covalent complexes in various molar ratios were synthesized and compared to the free enzyme in terms of pH, temperature, thermal and storage stabilities. Especially, the complex with a molar ratio of n_U/n_DA = 40/1 showed highest thermal stability and had ca. 1.4-fold at 25°C and 2.5-fold at 80°C higher activity than the free enzyme. The complex showed a high catalytic activity in organic solvent. In addition, the thermal and storage stabilities of urease were improved greatly as dextran complex, which has advantages for usage in practice.     

Thermo‐ and photo‐oxidative stability and improved processability of polyamide stabilized with a new functional additive

During processing polyamides can undergo thermo‐mechanical degradation due to the mechanical stress and to the high temperature applied to the melt. Degradation can occur also during the polyamides lifetime due to many driving forces, like temperature, ultraviolet radiations, etc. The mechanisms of degradation are not well understood and the stabilization with usual stabilizers, like phenol antioxidants, is not so efficient as for other classes of polymers. The aim of this work is the study of the effects of the addition of a new multifunctional additive on the processing and on the thermo‐ and photo‐stabilization of polyamide‐6. This additive is able to prevent the thermo‐mechanical degradation and also to enlarge the molecular weight distribution improving the processability of this polymer in operations where the elongational flow is involved. Moreover, the presence of this additive extends significantly the lifetime of the polyamide when subjected to thermo‐ and photo‐oxidative stress. Copyright © 2005 John Wiley & Sons, Ltd.     

A Luminescent and magnetic cyano-bridged Tb3+-Mo5+ coordination polymer: toward multifunctional materials

A new cyano-bridged coordination polymer network Tb(H2O)5-[Mo(CN)8] was obtained and characterized. This compound has a two-dimensional layered structure and presents luminescence along with a magnetic transition at low temperature.     

Properties of the surface of a porous polymer modified with 5-fluorouracil,according to data of gas chromatography

The effect or modification with 5-fluorouracil on the sorption activity of porous polymeric adsorbent is studied. It is demonstrated that the supramolecular structure formed on the surface is able to addition-ally contribute to the values of the specific retention volumes. It is found that the structure of 5-fluorouracil is capable of size effects corresponding to a molecular window of approximately 7–8 Å. It is concluded that surface polarity diminishes after modification, due to the shielding effect of four fluorine atoms present in the cavity.     

Highly graphitized carbon-wrapped PtFeCo alloy with enhanced durability and activity toward methanol electro-oxidation

Exploring efficient strategies to construct durable and active Pt-based electrocatalysts toward methanol oxidation reaction (MOR) remains great significance for the application of direct methanol fuel cells (DMFCs). Here, we report a facile pyrolysis procedure for fabricating carbon layer wrapped PtFeCo alloy nanoparticles supported on nitrogen-doped carbon nanotubes (NCNT). Physical characterizations demonstrate that the nitrogen-doped carbon support is highly graphitized and the PtFeCo particles are firmly wrapped by the graphitized carbon. Since the wrapping of highly graphitized carbon effectively prevents PtFeCo alloy from metal dissolution, the durability of the synthesized PtFeCo/Co–NCNT_a catalyst has been substantially improved, remaining about 76% of its initial mass activity after 1000 cycles of durability test in acid condition. In addition, due to the strain and ligand effects caused by alloying Pt with Fe and Co, the PtFeCo/Co–NCNT_a catalyst exhibits a greatly enhanced mass activity of 4.2-fold and a specific activity of 6.3-fold higher than those of commercial Pt/C-JM catalyst. Consequently, this work may provide an effective route for preparing durable and active Pt-based catalysts for methanol electro-oxidation.     

Modified composite cation exchange membrane with enhanced stability and electrochemical performance

Journal of Solid State Electrochemistry - Herein, we elaborated on the feasibility of coupling polyvinyl chloride with tin aluminium molybdophosphate to form composite membranes that facilitate...     

Phenyltetraene-based nonlinear optical chromophores with enhanced chemical stability and electrooptic activity

"Push-pull" phenyltetraene-based chromophores are too sensitive to be incorporated into Diels-Alder-type cross-linkable polymers due to the reactivity of its diene segment with maleimides. A facile synthetic route has been explored to incorporate a methoxy group into the R position of such chromophores, which reduces their diene reactivity during the poling and lattice hardening process. The poled polymers with one of such chromophores doped in a cross-linked polymer lattice showed ultrahigh electro-optic activities, up to 306 pm/V at 1310 nm.     

Encapsulation of single enzyme in nanogel with enhanced biocatalytic activity and stability

Single protein encapsulated into nanogels with uniformed size and controllable shell thickness were prepared by surface acryloylation of a protein molecule followed by aqueous in situ polymerization. Compared to its free counterpart, the encapsulated protein exhibits similar biocatalytic behavior and significantly improved stability at high temperature and in the presence of organic solvent.     

Reduced Ti-MOFs encapsulated black phosphorus with high stability and enhanced photocatalytic activity

The generation of green hydrogen(H_2) energy is of great significance to solve worldwide energy and environmental issues. Reduced Ti based photocatalyst has recently attracted intensive attention due to its excellent photocatalytic activity, while the synthesis of reduced Ti based photocatalysts with high stability is still a great challenge. Here, we report a facile method for synthesis of reduced Ti metal organic frameworks(small amounts of Pt incorporated) encapsulated BP(BP/R-Ti-MOFs/Pt) hybrid nanomaterial with enhanced photocatalytic activity. The strong interaction between Ti and P reduces the valence state of the binding Ti⁴⁺on the BP surface, forming abundant reduced Ti⁴⁺within R-Ti-MOFs/BP. Such reduced Ti⁴⁺render R-Ti-MOFs/BP efficient charge transfer and excellent light absorption capability, thus promote the photocatalytic H_2 production efficiency. Furthermore, the Ti-P interaction stabilizes both reduced Ti⁴⁺and BP during the photocatalytic reaction, which greatly enhanced the stability of the obtained BP/R-TiMOFs/Pt photocatalyst.     

Large electro‐optic activity and enhanced temporal stability of methacrylate‐based crosslinking hyperbranched nonlinear optical polymer

A methacrylate‐based crosslinking hyperbranced polymers have been synthesized through initiator‐fragment incorporation radical polymerization and used for the temperature stable electro‐optic (EO) polymer application. This polymer consists of methyl methacrylate, 2‐metacryloxyethyl isocyanate, and ethylene glycol dimethacrylate (EGDMA) monomers. The use of EGDMA as a bifunctional unit resulted in the solvent‐soluble crosslinking hyperbranched chain, so that the EO polymer enhanced glass transition temperatures. A phenyl vinylene thiophene vinylene bridge nonlinear optical chromophore was attached to the polymer backbone as the side‐chain by a post‐functionalization reaction. The loading concentration of the chromophore was varied between 30 and 50 wt % by simply changing the mixing ratio of the precursor polymer to the chromophore. The synthesized EO polymers produced optical quality films with a light propagation loss of 0.61 dB/cm in a slab waveguide at 1.31 μm. The electrically poled film had an EO coefficient (r₃₃) of 139 pm/V at 1.31 μm. The EO crosslinking hyperbranced polymer had a high‐glass transition temperature of 170 °C, and exhibited excellent temporal stability of the EO activity at 85 °C for 500 h. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and multidisciplinary characterization of polyelectrolyte multilayer-coated nanogold with improved stability toward aggregation

An interesting nanodrug delivery system is polyelectrolyte multilayer-coated nanogold. For better understanding of the binding of polycations or the counter-indicative deposition of polyanions on the citrate-stabilized gold nanoparticles, we used a surface-enhanced Raman spectroscopy to characterize the orientation of the polyions towards the gold surface. It was found that poly-allylamine replaces citrate molecules while the polyanion, poly-styrene sulfonate, intercalates in the citrate shell. One of the major obstacles for polyelectrolyte-coated nanogold is its tendency to agglomerate in the presence of high ion concentration as present, e.g., in blood. A novel encapsulation protocol for polyelectrolyte multilayer coating of gold nanoparticles was developed to successfully overcome this drawback. Moreover, electrostatic functionalization of the polyelectrolyte shell with a model target molecule for cancer, folic acid, induced a significant increase in the particle uptake in folate-receptor over-expressing breast cancer cell lines, VP 229 and MDA MB 231, compared to non-targeted particles or cells (non-activated macrophages) not expressing the folate receptor.