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A novel hierarchical structure of carbon nanotubes grown on Ni/NiO composite nanofiber has been in-situ fabricated by electrospinning and following low-temperature (500 °C) vacuum thermal treatment. During vacuum thermal treatment, decomposition of electrospun nickel acetate/polyvinylpolypyrrolidone precursor nanofibers generate gases as a function of both reducing agents and carbon sources for NiO reduction and carbon nanotubes growth. The thermal treatment processing parameter, i.e. heating rate, controls the morphology and composition of the resulting Ni nanofibers or Ni/NiO‑carbon nanotubes composite nanofibers. This proposed method avoid the usual extra introduction of reducing agents and carbon source. It is a low cost, high yield and safe no-hazard technique. Then, these non-noble metal-based nanofibers are applied as efficient electrocatalysts for the hydrogen evolution reaction in alkaline solution. The Ni/NiO‑carbon nanotubes (10 °C min−1) can drive 10 mA cm−2 at an overpotential of 98 mV in 1 M KOH, which is 52 mV less than for Ni nanofibers. This work offers promising novel catalyst materials in water-splitting devices for large-scale production of hydrogen fuel.

Selective entrapment of precious metals from industrial wastes containing various metals is a most challenging branch of environmental science. Developed methods like solvent or solid-phase extraction, ion exchange, co-precipitation, membrane filtration, and adsorption rely on chelation, electrostatic attraction, or ion exchange, and these methods present limited selectivity and require post-treatment for further application. Herein, an original concept is reported involving the utilization of the superior catalytic properties of Pd selectively for efficient entrapment of Pd from other metals. Specifically, side chains of poly(vinyl alcohol) (PVA) functionalized with alkynyl groups are catalytically dimerized using Pd(II), which forms gels. The Pd(II) ions are coordinatively encapsulated into the gel networks, while the other metal ions are excluded from the networks, thus allowing the separation and immobilization of Pd. The entrapped Pd(II) is also reduced to Pd(0) nanoparticles (PdNPs) forming PdNPs@al...

Ion transport is crucial for biological systems and membrane-based technologies from both fundamental and practical aspects. Unlike biological ion channels, realizing efficient ion sieving by using membranes with artificial ion channels remains an extremely challenging task. Inspired by biological ion channels with proper steric containment of target ions within affinitive binding sites along the selective filter, herein we design a system of biomimic two-dimensional (2D) ionic transport channels based on a graphene oxide (GO) membrane, where the ionic imidazole group tunes the appropriate physical confinement of 2D ionic transport channels to mimic the confined cavity structures of the biological selectivity filter, and the ionic sulfonic group creates a favorable chemical environment of 2D ionic transport channels to mimic the affinitive binding sites of the biological selectivity filter. As a result, the as-fabricated ionic GO membrane demonstrates an exceptional K+ transport rate of ∼1.36 mol m-2 h-1 and competitive K+/Mg2+ selectivity of ∼9.11, outperforming state-of-the-art counterparts. Moreover, the semiquantitative studies of ion transport through 2D ionic transport channels suggest that efficient ion sieving with the ionic GO membrane is achieved by the high diffusion and partition coefficients of hydrated monovalent ions, as well as the large energy barrier and limited potential gradient of hydrated divalent ions encountered.

A novel tridentate ligand nitrilotris(methylene)tris(1,2,3-triazole)triacetate (NTTTA) has been synthesized by click reaction and followed with ester hydrolysis reaction. The silver nanoparticles (AgNPs) were then modified and stabilized by this ligand, and subsequently been employed for the highly selective and sensitive colorimetric detection of Mn2+ in aqueous solution. The presence of Mn2+ can cause the aggregation of AgNPs, which leads to the color change of the dispersion from yellow to brown, as well as the decrease and red-shift of the surface plasmon resonance absorption. The detection limit of Mn2+ was as approximately 0.5 μM by the naked eyes. UV–vis spectroscopy analysis showed a good linear relationship between the logarithm of the ratios (A550/A395) and the concentration of Mn2+over the range of 0.05 μM–10 μM, and the LOD was calculated to be 12.6 nM (S/N = 3). The present assay showed good simplicity without the need of adjusting the pH value. The feasibility of this technique was evaluated for successful detection of Mn2+ in tap water and lake water samples, with good recoveries.

The metal catalysts encapsulated in nanomaterials have recently been applied successfully in bioorthogonal chemistry for intracellular generation of bioactive compounds. However, the nanomaterial-involved intracellular catalysis is intrinsically different from that in solution or in extracellular fluid. Except for the reactivity of metal catalyst itself, the supporting material’s morphology and biocompatibility are essential factors for building optimal nanocatalysts. Herein, we present a new nanocopper-doped cross-linked lipoic acid nanoparticle (Cu@cLANP) that meets the stringent requirements for the intracellular nanocatalyst. It comes from endogenous lipoic acid and can easily achieve the morphology change by different reduction methods. The optimal rugbylike Cu@cLANPs I did show much better catalytic efficiency for intracellular azide–alkyne cycloaddition than that of the other two spherical nanocatalysts Cu@cLANPs II and III, hinting at the importance of nanoparticle morphology for the intracellular...

We report that the co-solvent polarity can precisely control the TPE-buried amphiphile 1 to self-assemble into nanoparticles (NPs) in water with size range from ∼21–32 nm to 55–68 nm to 95–106 nm. Excepted for size, these TPE-buried amphiphile fabricated NPs hold identical physical properties such as spherical shape, surface charge, and luminescent properties, and moreover, after covalent capture of the acrylate hydrophilic heads, the resulting cross-linked NPs (cNPs I–III) own excellent in vivo stability, which thus would be an ideal platform for investigating the size effects on tumor accumulation and penetration.

MXenes, a new, very recently emerging family of two-dimensional (2D) early transition metal carbides and/or nitrides, has attracted a great influence in the fields of physics, material science, chemistry, and nanotechnology. In this review, their synthesis, compelling physical, chemical, as well as their various potential applications in catalysis, sensors and adsorption are highlighted. First, the synthesis, structural variety, and chemical and physical properties are summarized. Then the electroactivity, durability, ease of functionalization of MXenes toward electrocatalysis and photocatalysis applications are introduced. The specific properties of metallic conductivity, biocompatibility, hydrophilic surface, and 2D layered atomic structure that make MXenes promising candidates in sensing of rapid, easy, and label-free detection are consequently discussed. Finally, how MXenes could be considered as ideal adsorbents due to the advantages of large surface area and abundant active sites is underlined. Promising theoretical calculations and first remarkable performances in these applications are also highlighted.

A self-healing and recyclable carbon tube/epoxy adhesive was prepared by epoxy monomer with Diels-Alder (DA) bonds, diethylenetriamine and polyethyleneimine modified multi-wall carbon nanotubes (MWCNTs). The self-healing and recyclable ability was attained by thermally reversible Diels-Alder reaction between furan and maleimide in the epoxy monomer. By controlling the molar ratio of furfuryl glycidyl ether and 4,4′-methylenebis(N-phenylmaleimide), the glass transition temperature and mechanical properties of MWCNTs/epoxy adhesives were varied. The self-healing properties of MWCNTs/epoxy polymers were evaluated by lap shear experiment and the results showed that the MWCNTs/epoxy adhesives exhibited enhanced mechanical properties and excellent self-healing ability under heat stimulus. The healing efficiency was related to the molecule mobility and the conversion of DA reaction between furan and maleimide. The MWCNTs/epoxy adhesives also displayed excellent recyclable ability by transforming into soluble polymer under heating. These materials offer a wide range of possibilities to produce materials with healing and recyclable ability and have the potential to bring great benefits to our daily lives by enhancing the safety, performance, and lifetime of products.

Since an early report in the 1970s, the mesoscale inhomogeneities formed in an aqueous solution of water-miscible small organic molecules have been debated for over forty years with a variety of explanations. Although it was recently established that these inhomogeneities are supramolecular species caused by trace impurities, the structure of the supramolecular species and the mechanism behind their formation are not yet clear. By means of covalent capture, we herein disclose that the formation mechanism of the supramolecular species consists of a two-step self-assembly process: the small molecules first assemble into primary micelles with a trace amount of impurity, and the formed dynamic ultra-small micelles aggregate further through hydrogen bonding to achieve a buildup of thermodynamic mesoscale inhomogeneities. Based on this finding, supramolecular species have been used as elements for pH-responsive size-changeable drug carriers, which respond to the acidic tumour extracellular milieu and decompose into small particles for deep tumour penetration and effective distribution.

Safety use of hydrogen leads to the development of highly sensitive materials for hydrogen sensing. Herein, Pd(II)@alkyne-PVA/d-Ti3C2Tx composite was prepared by spin-coating Pd(II)@alkyne-PVA solution onto the filter membrane supported with delaminated Ti3C2Tx (d-Ti3C2Tx). The properties of the composite were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results demonstrate that the composite shows high sensitivity and stability for hydrogen sensing.

Nitrilotriacetate (NTA) has been reported to behave as both a reductant and a stabilizer for gold nanoparticle (AuNP) preparation in a one-pot synthesis and colorimetric assay. The goal of this study was to avoid the negative influence of citrate residues in the detection of chromium ions because citrate always remains in the modification of AuNPs via common ligand-exchange methods. This colorimetric assay was shown to be highly efficient and selective for the detection of Cr(III) and Cr(VI). The detection limit of Cr(III) by the naked eye was as low as 2.0 μM. Interestingly, a much lower detection limit was found for Cr(VI) than that for Cr(III) (0.4 μM by the naked eye). In addition, Cr(III) and Cr(VI) were easily distinguished upon pretreatment with K2CO3. The feasibility of this technique was evaluated for the successful detection of Cr(III) and Cr(VI) in tap water samples with good recoveries. The detection mechanism has been discussed via several techniques including transmission electron microscopy (TEM), FT-IR spectroscopy, zeta potential (ζ-potential) measurement, and inductively coupled plasma mass spectrometry (ICP-MS).

Epoxy polymer with damage indicating ability was very usable for ships and bridges to detect the cracks at an early stage and to prevent corrosion. 2′, 7′-dichlorofluorescein (DCF), as a damage indicator, was used to report the mechanical damage of epoxy-amine polymer by a strong color change from a light yellow to bright red due to the molecular structure transition from the acid molecular form to the base ion form. The effect of water on damage indicator and damaged epoxy-amine polymer film was evaluated by an immersion test and the properties were characterized by ultraviolet-visible spectrophotometry (UV-Vis), scanning electronic microscopy (SEM), energy dispersive X-ray spectrometer (EDS), zeta potential and thermal gravimetric analysis (TGA). The results showed that DCF was an easy, stable and permanent indicator for epoxy-amine polymer and the water only had a slight influence on the indication stability of damaged epoxy polymer.

Technical alkaline lignin was first pretreated with alkaline hydrogen peroxide and then liquefied using methanol-water mixture or methanol solvents. When the technical lignin was pretreated by 0.5% H 2 O 2 at 80 °C, the liquid yield of the liquefaction in methanol-water mixture and methanol increased from 84.2% to 93.5% and from 79.2% to 90.5%, respectively. The alkaline lignin (AL), pretreated lignin (PL) and resulting liquid (RL) were characterized by using GPC, FT-IR, and 1 H NMR methods. The GPC results illustrated that the pretreatment by 0.5% H2O2 could decrease the weight average (Mw) and number average (Mn) molecular weight from 1692 to 1354 g/mol and from 1376 to 1207 g/mol, respectively. The FT-IR and 1H NMR results confirmed that some phenols were oxidized to quinone or aliphatic chain structures, and parts of side chains were separated from lignin.

A remarkable property of metallocenes, in particular those of the late first-row transition metals, is their redox function including the stability of two or several oxidation states. Recently our groups have introduced these compounds into precise dendrimers and polymers in view of sensing and catalytic applications. This short overview essentially focuses on the synthetic aspects and applications of our research conducted in this area.

A short overview of colorimetric and fluorescence detection with gold nanoparticle (AuNP) sensors of chemical warfare agents (CWAs) is provided. This review of CWA sensing includes nerve agents, vesicant agents, pulmonary agents, cytotoxic proteins, suffocating/blood agents, incapacitating agents, and lachrymatory. The sensing methods are based on the optical (surface plasmon band) and other physico-chemical properties of appropriately functionalized AuNPs.

Metal-organic frameworks have remarkable advantages of high specific surface area, tunable pore structure, species diversity and superior stability causing it be a good adsorbent for methylene blue removal. Here, UiO-66 was prepared by two-step simple method at room temperature, then the effects of water on morphology, crystallinity and adsorption properties of UiO-66 were studied. UiO-66 exhibits good adsorption performance of MB with maximum adsorption amount of 543.48 mg g−1 and good cycling stability.

Diblock metallopolymer polyelectrolytes containing the two redox-robust cationic sandwich units [CoCp'Cp](+) and [FeCp'(η(6)-C6 Me6)](+) (Cp = η(5)-C5 H5; Cp' = η(5)-C5H4-) as hexafluorophosphate ([PF6](-)) salts are synthesized by ring-opening metathesis polymerization using Grubbs' third generation catalyst. Their electrochemical properties show full chemical and electrochemical reversibilities allowing fine determination of the copolymer molecular weight using Bard-Anson's electrochemical method by cyclic voltammetry.

As one of the most general and promising stabilizers, dendrimers have been widely used to prepare ultra-small gold nanoclusters. However, the complex synthesis of dendrimers hinders the further application of protected nanoclusters. Here we report a facile strategy to prepare an alternative material via core cross-linking of self-assembled micelles. The resulting dendrimer-like core cross-linked micelles (DCCMs) retain the main characteristics of dendrimers and avoid complex chemical synthesis. As expected, the DCCMs could easily encapsulate gold nanoparticles within their cores. The ultra-small clusters of Au5 were prepared without the participation of external reductants. Importantly, the DCCM stabilized noble gold clusters furnish excellent catalytic activity and perfect reusability for aerobic oxidation of α-hydroxy ketones in water. Only in open air the oxidation could be repeated up to 48 times with negligible turn-over frequency change. The total turnover number (TON) of the reaction reached unexpectedly >48000, the highest TON for metal catalysed oxidation of hydroxy ketones so far. The further mechanism study hints that the carboxylic group of substrates might be involved in the catalytic process. The simple catalyst preparation, the environmentally benign reaction conditions, and the excellent catalytic performance and durability make the novel DCCM protected gold nanocluster a green catalyst.

Sugarcane bagasse (SCB) was modified by steam explosion pretreatment at 190 °C for 10 min and 210 °C for 5 min using green liquor (GL) combined with hydrogen peroxide (GL-H2O2) and ethanol (GL-Ethanol) for simultaneous saccharification and fermentation (SSF)-based ethanol production. The results showed that 85.02% and 100% of hemicelluloses were solubilized by steam explosion pretreatment at 190 °C for 10 min and 210 °C for 5 min, respectively. Moreover, 20.08% and 73.77% of the lignin was removed through GL-H2O2 and GL-Ethanol pretreatments, respectively. The steam explosion pretreatments greatly improved the specific surface area of the SCB and led to the highest ethanol yield of 92.20% at 190 °C for 10 min and 93.19% of 210 °C for 5 min, respectively. In addition, the ethanol yield reached 72.58% for the GL-Ethanol pretreatment, and about 70% of active lignin could be recovered from the pretreatment liquid. When the GL-H2O2 pretreatment was used, the maximum ethanol yield of 20.92% was achieved.

The design of redox-robust metallocopolymers is expected to produce new nanomaterials with multiple applications. Here the ROMP syntheses using Grubbs’ 3rd generation catalyst of three new living diblock copolymers each containing two distinct redox-stable iron sandwich complexes of the ferrocene, pentamethylferrocene and cyclopentadienyl-iron-arene families in the side chain are reported. The electrochemical properties of these diblock metallocopolymers investigated by cyclic voltammetry show complete chemical and electrochemical reversibilities of the redox waves, which also allow using the Bard–Anson method to determine the number of monomer units. The selective and reversible “chemical” oxidation of one of the blocks in two of these metallocopolymers afforded the syntheses of mixed-valent FeIIFeIII polymers.

Controlled wettability of liquids on bioceramic surfaces has recently received widespread attention. Here, tunable wettability of yttria-stabilized tetragonal zirconia polycrystals (Y-TZP, 3 mol% yttria) bioceramic surface was achieved by ultrafast laser micro-fabrication. Two surface microstructures, arc grooves and square pillar arrays, were designed based on the Wenzel and Cassie model, and then fabricated by 355 nm picosecond laser with high controllability and quality. The contact angle of the treated surface was tunable from superhydrophilicity (10°) to hydrophobicity (133°) by changing the microstructure characteristics with laser processing. The microstructures with uniform size, crack-free, smooth edges and alleviated taper were achieved. In addition, the laser-treated Y-TZP ceramic surfaces were biocompatible for cell adhesion and growth. The range of the optimized parameters was also determined based on the study of the interaction of the laser with the Y-TZP ceramics.

Novel mesoporous graphitic carbon nitride (g-C3N4) was synthesized via one-step thermal condensation of ethyl cellulose (EC) and urea mixture. Morphology, crystal structure and charge carrier lifetime of the composites were controlled by tuning the amount of EC. The optimized 5 wt% EC/g-C3N4 (OEC/g-C3N4), which showed the highest surface area and longest carrier lifetime, were facilely incorporated into the ZnO nanosheet by the hydrothermal method as catalyst for methylene blue degradation under visible-light irradiation. The optimized photocatalytic activity of OEC/g-C3N4/ZnO nanosheets at a weight ratio of 3% under visible-light irradiation is almost 8.5 times higher than that of ZnO nanosheets. This enhancement in performance is mainly attributed to OEC/g-C3N4 incorporation, which broadens the light absorption and facilitates the separation and transfer of photogenerated electron–hole pairs at the interface. In addition, this method is expected to be extended to other EC/g-C3N4 loaded materials.

Featuring the advantages of both homogeneous (high activity) and heterogeneous (recyclability) catalysts, heterogenized homogeneous catalysts (e.g., dendrimer-stabilized metal nanoparticles) have received much attention in recent years. Here, we develop a new triazole-containing dendrimer-like core cross-linked micelle (DCCM) stabilized Pd nanoparticles as a highly efficient heterogenized homogeneous catalyst for the Suzuki-Miyaura reaction. Both arylboronic acids and iodobenzenes with diverse electronic properties performed with excellent reactivity under the mild conditions of room temperature, water as the sole solvent, and as low as 0.5 % catalyst loading. Importantly, the Pd@triazole-DCCMs can tolerate various functional groups well (e.g., alcohol, aldehyde, ester, acyl, amino, and cyano, etc.) and give the corresponding biphenyl products in high yields. Recycling experiments suggest that the new heterogenized homogeneous catalyst can be recovered simply and reused many times with negligible activity change.

A remarkable property of metallocenes, in particular those of the late first-row transition metals, is their redox function including the stability of two or several oxidation states. Recently our groups have introduced these compounds into precise dendrimers and polymers in view of sensing and catalytic applications. This short overview essentially focuses on the synthetic aspects and applications of our research conducted in this area.

A report by the Federal Highway Administration (FHWA) in the USA stated that there are over 1.4 million miles (2.3 million kilometres) of unpaved roads in the United States, over 1/3 of the U.S highway systems. Unpaved roads play an important role in transporting goods and passengers in between urban and suburban areas. However, most unpaved roads are gravel and unimproved that have exposed a severe issue for local transportation networks. Particularly when unpaved roads are in wet conditions (rain or snow), the muddy and soft surface roads have created a hazardous environment for traffic operations. The paper presents an improvement plan using co-polymer dust suppressants to be mixed with soils collected in Northern Arizona. Soil samples were mixed with the co-polymer dust suppressants using four concentration rates (0% water, 1%, 3%, and 5% by weight). A series of tests were performed including surface strength (resistant penetration) test, dynamic rolling test, and unconfined compressive shear test. The results show that the addition of co-polymer dust suppressants in the soil has improved the soil shear strength and decreased dust emissions, provided the results from the surface strength test, dynamic rolling test, and unconfined compressive strength test are promising.

An enzyme-free and label-free colorimetric Pb(2+) sensor based on DNAzyme and molecular beacon (MB) has been developed and demonstrated by recycle using enzyme strand for signal amplification. The substrate strand DNA (S-DNA) of DNAzyme could be converted into MB structure with base pairs of stem part at the both ends. The MB could hybridize with enzyme strand DNA (E-DNA) to form DNAzyme, and be activated and cleaved in the presence of Pb(2+). The cleaved MB is much less stable, releasing from the DNAzyme as two product pieces. The product pieces of MB are flexible and could bind to unmodified AuNPs to effectively stabilize them against salt-induced aggregation. Then, the E-DNA is liberated to catalyze the next reaction and amplify the response signal. By taking advantage of repeated using of E-DNA, our proposed method exhibited high sensitive for Pb(2+) detection in a linear range from 0.05 to 5 nM with detection limit of 20 pM by UV-vis spectrometer. Moreover, this method was also used for determination of Pb(2+) in river water samples with satisfying results. Importantly, this strategy could reach high sensitivity without any modification and complex enzymatic or hairpins based amplification procedures.

International audience; The stereoelectronic properties of the stabilizing ligands of gold nanoparticles (AuNPs) are shown to play a considerable role in their catalytic efficiency for 4-nitrophenol reduction by NaBH4, consistent with a mechanism involving restructuration of the AuNP surface that behaves as an "electron reservoir".

International audience; A large family of bifunctional 1,2,3-triazole derivatives that contain both a polyethylene glycol (PEG) chain and another functional fragment (e.g., a polymer, dendron, alcohol, carboxylic acid, allyl, fluorescence dye, redox-robust metal complex, or a β-cyclodextrin unit) has been synthesized by facile "click" chemistry and mildly coordinated to nanogold particles, thus providing stable water-soluble gold nanoparticles (AuNPs) in the size range 3.0-11.2 nm with various properties and applications. In particular, the sensing properties of these AuNPs are illustrated through the detection of an analogue of a warfare agent (i.e., sulfur mustard) by means of a fluorescence "turn-on" assay, and the catalytic activity of the smallest triazole-AuNPs (core of 3.0 nm) is excellent for the reduction of 4-nitrophenol in water.

International audience; Carboranes that have a high boron content are key materials for boron neutron capture therapy (BNCT), while PEGylated gold nanoparticles (AuNPs) are also most useful in various aspects of nanomedicine including photothermotherapy, imaging and drug vectorization. Therefore, methods to assemble these key components have been investigated for the first time. Strategies and results are delineated in this article, and the nanomaterials have been characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), UV–vis., mass and multinuclear NMR data. A series of well-defined water-soluble bifunctional AuNPs containing carborane and polyethylene glycol (PEG) were synthesized through either two-step Cu(I)-catalyzed azide–alkyne cycloaddition CuAAC (“click”) reactions at the periphery of azido-terminated AuNPs in the presence of the efficient catalyst [CuItren(CH2Ph)6][Br] or simply by direct stabilization of AuNPs using a tris-carborane thiol dendron or a hybrid dendron containing both PEG and carborane.

International audience; "Click" chemistry now offers access to a great variety of triazoles, and the first example of a strategy to stabilize gold nanoparticles (AuNPs) with a new 1,2,3-triazole-mPEG ligand is developed here together with preliminary examples of possible applications.

International audience; Ultrathin films of molecular spin crossover materials exhibit very appealing properties for a variety of photonic applications because the spin-state switching is accompanied by a spectacular change of the complex refractive index in a wide spectral range. After examining different optical spectroscopic approaches for the detection of spin-state changes in nanometric films, we found that conventional light absorption measurements can be used down to the nanometer thickness if the oscillator strength of the transition is high, which is often the case for charge transfer transitions in the ultraviolet range. Methods based on fluorescence energy transfer provide a straightforward means for detecting spin-state changes in films in the visible wavelength range, even if photobleaching may be a problem for certain luminophores. Alternatively, changes in the refractive index accompanying the spin transition can be conveniently determined by surface plasmon resonance spectroscopy, which can also provide very accurate film thickness determination. Plasmonic effects were also used to investigate spin-crossover films by means of surface-enhanced Raman spectroscopy. We found that this technique can provide information not only on the spin state of the molecules in very thin layers, but also on their chemical composition and structure.