Mechanically Robust, Recyclable, and Self-Healing Polyimine Networks.

To achieve energy saving and emission reduction goals, recyclable and healable thermoset materials are highly attractive. Polymer copolymerization has been proven to be a critical strategy for preparing high-performance polymeric materials. However, it remains a huge challenge to develop high-performance recyclable and healable thermoset materials. Here, polyimine dynamic networks based on two monomers with bulky pendant groups, which not only displayed mechanical properties higher than the strong and tough polymers, e.g., polycarbonate, but also excellent self-repairing capability and recyclability as thermosets are developed. Owing to the stability of conjugation effect by aromatic benzene rings, the final polyimine networks are far more stable than the reported counterparts, exhibiting excellent hydrolysis resistance under both alkaline condition and most organic solvents. These polyimine materials with conjugation structure can be completely depolymerized into monomers recovery in an acidic aqueous solution at ambient temperature. Resulting from the bulky pendant units, this method allows the exchange reactions of conjugation polyimine vitrimer easily within minutes for self-healing function. Moreover, the introduction of trifluoromethyl diphenoxybenzene backbones significantly increases tensile properties of polyimine materials. This work provides an effective strategy for fabricating high-performance polymer materials with multiple functions.

Self-Healable, Malleable, Ecofriendly Recyclable and Robust Polyimine Thermosets Derived from Trifluoromethyl Diphenoxybenzene Backbones.

Dynamic covalent chemistry opens up great opportunities for a sustainable society by producing reprocessable networks of polymers and even thermosets. However, achieving the closed-loop recycling of polymers with high performance remains a grand challenge. The introduction of aromatic monomers and fluorine into covalent adaptable networks is an attractive method to tackle this challenge. Therefore, we present a facile and universal strategy to focus on the design and applications of polyimine vitrimers containing trifluoromethyl diphenoxybenzene backbones in applications of dynamic covalent polymers. In this study, fluorine-containing polyimine vitrimer networks (FPIVs) were fabricated, and the results revealed that the FPIVs not only exhibited good self-healability, malleability and processability without the aid of any catalyst, but also possessed decent mechanical strength, superior toughness and thermal stability. We hope that this work could provide a novel pathway for the design of high-performance polyimine vitrimers by recycling of plastic wastes.

Enhancing the spatial separation of photogenerated charges on Fe-based MOFs via structural regulation for highly-efficient photocatalytic Cr(VI) reduction.

Although iron-based metal-organic frameworks (Fe-MOFs) have displayed the photocatalytic activity, there is still abundant room for improving their photocatalytic performance through tuning the structures. In this work, four novel iron-based metal-organic frameworks (Fe-MOFs) were successfully synthesized via ligand modulation for better photocatalytic Cr(VI) reduction, in which MTBDC-TPT-Fe had the highest catalytic activity (MTBDC = 2,5-bis(methylthio)terephthalic acid, TPT = 2,4,6-tri(4-pyridyl)- 1,3,5-triazine). The boosted photocatalytic reduction may be mainly ascribed to the enhanced electron push-pull effect between iron-oxygen clusters and organic ligands. The introduction of -SCH3 groups can enhance the light absorption and donate electrons to iron center under visible-light irradiation, meanwhile the separation and transfer of photogenerated charge carriers can be enhanced resulting from the electron-pulling effect when introducing TPT. Moreover, enhanced specific surface areas and positive skeleton charge due to the introduction of TPT may improve active sites exposure and Cr(VI) adsorption, thereby enhancing photocatalytic Cr(VI) reduction activity without the presence of any assisted scavengers. In addition, the photocatalytic mechanism (i.e. active species) were also studied and presented. This work confirmed an effective structure-performance regulation strategy on Fe-MOFs for photocatalytic Cr(VI) reduction.

Novel C3N4-Assisted Bilateral Interface Engineering for Efficient and Stable Perovskite Solar Cells.

g-C3N4-assisted interface engineering has been developed as an effective method to improve the efficiency and stability of perovskite solar cells (PSCs). However, most of the reported works used g-C3N4-induced single-interface modification, which is difficult to passivate the bilateral interfaces of the perovskite layer at the same time. In this paper, we fabricated two kinds of C3N4 materials simultaneously (w-CN and y-CN) after the twice calcination of melamine and used them in the bilateral interface modification toward all-inorganic PSCs. The two kinds of C3N4 play different roles in different interface engineering. On the front interface, w-CN could optimize band level arrangement and improve the perovskite film quality, which contributes to the efficiency of the device. On the back interface, y-CN could also improve the film quality of the perovskite layer, accelerating the extraction of charge carriers. The champion efficiency of the CsPbIBr2-based device treated by the bilateral interface is significantly enhanced from 7.8 to 10.1%. Moreover, the modified perovskite film exhibits negligible degradation after 40 min of exposure in the ambient environment with a relative humidity of 70%, while the pristine perovskite film has a rapid degradation within 20 min.

Cerium oxide modified iridium nanorods for highly efficient electrochemical water splitting.

An Ir/CeO2 composite catalyst with Ir nanorods (NRs) on amorphous CeO2 was synthesized through a facile one-pot hydrothermal method, which shows excellent activity towards hydrogen evolution and oxygen evolution in alkaline media, even superior to the performance of commercial Pt/C, IrO2 and RuO2 catalysts. The enhanced performance could be attributed to the interfacial electron synergistic effect between Ir and CeO2.

Assembly of Two Mesoporous Anionic Metal-Organic Frameworks for Fluorescent Sensing of Metal Ions and Organic Dyes Separation.

Anionic metal-organic frameworks (MOFs) have attracted increasing attention due to the enhanced electrostatic interactions between their anionic frameworks and counter-ionic guests. Owing to these special host-guest interactions, anionic MOFs are beginning to have a large impact in the field of absorption and separation of ionic molecules and selective sensing of metal ions. Herein, two mesoporous anionic metal-organic frameworks, namely, [(CH3)2NH2]6[In6(OX)6(TCA)4]·solvents (JOU-11) and [(CH3)2NH2]6[In6(OX)6(TCPA)4]·solvents (JOU-12) (H3TCA = tricarboxytriphenylamine; H3TCPA = tris((4-carboxyl)phenylduryl)amine; OX = oxalate), have been synthesized by using wheel-type [In6(OX)6(COO)12]6- as building blocks. Structural analyses show that JOU-11 and JOU-12 show isoreticular three-dimensional frameworks with pyr topology. Due to their anionic frameworks and tunable pore window sizes, both compounds can be exploited for absorbing and separating cationic organic dyes. In addition, JOU-11 can be developed as a fluorescence "turn-off" sensor for selectively sensing Fe3+, whereas JOU-12 can be used for fluorescence "turn-on" sensing of Cu2+ and Co2+ ions.

One-step preparation of sulfur-doped porous g-C3N4 for enhanced visible light photocatalytic performance.

Nonmetal doping is a convenient method to adjust the visible light photocatalytic activity of graphitic carbon nitride (g-C3N4). Herein, highly active sulfur-doped porous g-C3N4 (C3N4-S) was successfully prepared by one-step calcination using thiourea and melamine as the precursors. C3N4-S exhibited excellent photocatalytic performance for the degradation of Rhodamine B (RhB) under visible light irradiation. C3N4-S not only promoted the separation of photogenerated electron-hole pairs, but also enhanced electron transfer, resulting in a great improvement in the photocatalytic efficiency. Based on capture experiments and DMPO spin-trapping ESR spectra, the superoxide radical (˙O2-) was proved to be the predominant active species and the possible photocatalytic mechanism of C3N4-S was proposed. The photocatalytic mechanism of RhB degradation over C3N4-S was further explored using high-resolution mass spectra (HRMS).

Yolk-shell hierarchical catalyst with tremella-like molybdenum sulfide on transition metal (Co, Ni and Fe) sulfide for electrochemical water splitting.

Tremella-like MoS2 nano-sheets were directly synthesized on transition metal sulfides (TMS) via a solvothermal method, displaying extreme activities towards hydrogen and oxygen evolution in alkaline condition. The enhanced performance is attributed to the synergistic effect between the MoS2 shell and TMS yolk, expanded interlayer distance and the hierarchical structure.

Synthesis of octahedral Pt-Ni-Ir yolk-shell nanoparticles and their catalysis in oxygen reduction and methanol oxidization under both acidic and alkaline conditions.

Fuel cells are expected to be one of the most promising alternatives to the increasingly scarce fossil fuels, and Pt is the most commonly used catalyst for anodic and cathodic electrochemical reactions. To realize large-scale commercialization, it is most urgent to improve the efficiency of Pt and reduce the cost. Here, we synthesized an octahedral Pt-Ni-Ir yolk-shell catalyst through stepwise co-deposition (SCD), surface-limited Pt deposition (SLPD) and Ni-coordinating etching (NCE) processes. Experimental studies showed that the catalytic activities of the as-prepared trimetal yolk-shell catalyst were several times higher than that of the commercial Pt/C towards oxygen reduction and methanol oxidization under both acidic and alkaline conditions. This work may be extended to designing other multimetallic functional materials with complex hierarchical nanostructures, which is conducive to greatly enhancing the performance.

Efficient Photocatalytic Degradation of Malachite Green in Seawater by the Hybrid of Zinc-Oxide Nanorods Grown on Three-Dimensional (3D) Reduced Graphene Oxide(RGO)/Ni Foam.

A hybrid of ZnO nanorods grown onto three-dimensional (3D) reduced graphene oxide (RGO)@Ni foam (ZnO/RGO@NF) is synthesized by a facile hydrothermal method. The as-prepared hybrid material is physically characterized by SEM, XRD, Raman, and X-ray photoelectron spectroscopy (XPS). When the as-prepared 3D hybrid is investigated as a photocatalyst, it demonstrates significant high photocatalytic activity for the degradation of methylene blue (MB), rhodamine (RhB), and mixed MB/RhB as organic dye pollutants. In addition, the practical application and the durability of the as-prepared catalyst to degradation of malachite green (MG) in seawater are firstly assessed in a continuous flow system. The catalyst shows a high degradation efficiency and stable photocatalytic activity for 5 h continuous operation, which should be a promising catalyst for the degradation of organic dyes in seawater.

Pt-Pd Bimetal Popcorn Nanocrystals: Enhancing the Catalytic Performance by Combination Effect of Stable Multipetals Nanostructure and Highly Accessible Active Sites.

Exploration of highly efficient electrocatalysts is significantly urgent for the extensive adoption of the fuel cells. Because of their high activity and super stability, Pt-Pd bimetal nanocrystals have been widely recognized as one class of promising electrocatalysts for oxygen reduction. This article presents the synthesis of popcorn-shaped Pt-Pd bimetal nanoparticles with a wide composition range through a facile hydrothermal strategy. The hollow-centered nanoparticles are surrounded by several petals and concave surfaces. By exploring the oxygen reduction reaction on the carbon supported Pt-Pd popcorns in perchloric acid solution, it is found that compared with the commercial Pt/C catalyst the present catalysts display superior catalytic performances in aspects of catalytic activity and stability. More importantly, the Pt-Pd popcorns display minor performance degradations through prolonged potential cycling. The enhanced performances can be mainly attributed to the unique popcorn structure of the Pt-Pd components, which allows the appearance and long existence of the high active sites with more accessibility. The present work highlights the key roles of accessible high active sites in the oxygen reduction reaction, which will ultimately guide the design of highly durable Pt-Pd catalysts.

One-Pot Synthesis of Concave Platinum-Cobalt Nanocrystals and Their Superior Catalytic Performances for Methanol Electrochemical Oxidation and Oxygen Electrochemical Reduction.

Exploring highly efficient electro-catalysts is of significant urgency for the widespread uptake of the direct methanol fuel cells (DMFCs). Pt-Co nanocrystals have attracted considerable attentions because of their superior catalytic performance toward both methanol oxidation and oxygen reduction in the preliminary assessments. This Research Article presents a Pt-Co bimetal catalyst that is synthesized through a facile coreduction strategy. The Pt-Co nanocrystals have concave cubic shape with a high uniform size of 7-9 nm and Pt-rich surfaces. The catalysis of the concave cubic Pt-Co nanoparticles toward both methanol electrochemical oxidation reaction (MOR) and oxygen electrochemical reduction reaction (ORR) is evaluated. In comparison with the commercial Pt/C catalyst (Johnson Matthey), the present concave cubic Pt-Co catalyst displays superior performances in not only catalytic activity but also durability. The concave Pt-Co catalyst also shows higher activities than spherical and cubic Pt-Co nanoparticles. The dramatic enhancement is mainly attributed to its alloyed composition, Pt-rich surface and the concave nanostructure. The results of our research indicate that the concave Pt-Co nanocrystal could be a promising catalyst for both MOR and ORR. The present work might also raise more concerns on exploiting morphology and composition of nanocrystal catalysts, which are expected to provide high catalytic performance in electrochemical reactions.

High Durable Ternary Nanodendrites as Effective Catalysts for Oxygen Reduction Reaction.

Exploiting high catalytic activities and superior durability is significant for the lifetime and the cost of electro-catalysts for oxygen reduction reaction (ORR). Pt-Ni nanocrystals have attracted considerable attention owing to their exceptionally catalytic performance. However, the durability of Pt-Ni nanoparticles in acid media is still far below satisfaction. Consequently, improving the durability is extremely urgent for the application of Pt-Ni catalysts. To this end, we herein develop Pt-Ni-Ir ternary nanocrystals with dendritic shape, which are synthesized through a facile one-pot strategy. Such nanostructures featured with multibranches show an area specific activity of 1.58 mA cm(-2), seven times more than that of the commercial Pt/C catalyst (0.21 mA cm(-2)). More importantly, the dendritic Pt-Ni-Ir catalyst displays extraordinarily high durability. In contrast to the commercial Pt/C counterparts, which exhibit losses of 53.2% in EASA and 41% in area specific activity after 12 000 cycles of sweeping in the potential range of 0.6-1.1 V, only respective losses of 5.5% and 6% are detected for our dendritic Pt-Ni-Ir catalyst. The high activity and remarkable durability are mainly attributed to the dendritic morphology and the introduction of Ir. This work demonstrates that the Pt-Ni-Ir dendritic nanostructures are promising electro-catalysts for ORR.

Electrochemical nonenzymatic sensor based on CoO decorated reduced graphene oxide for the simultaneous determination of carbofuran and carbaryl in fruits and vegetables.

A novel nonenzymatic sensor based on cobalt (II) oxide (CoO)-decorated reduced graphene oxide (rGO) was developed for the detection of carbofuran (CBF) and carbaryl (CBR). Two well-defined and separate differential pulse voltammetric peaks for CBF and CBR were obtained with the CoO/rGO sensor in a mixed solution, making the simultaneous detection of both carbamate pesticides possible. The nonenzymatic sensor demonstrated a linear relationship over a wide concentration range of 0.2-70 µM (R=0.9996) for CBF and 0.5-200 µM (R=0.9995) for CBR. The lower detection limit of the sensor was 4.2 µg/L for CBF and 7.5 µg/L for CBR (S/N=3). The developed sensor was used to detect CBF and CBR in fruit and vegetable samples and yielded satisfactory results.

Mapping three-dimensional temperature in microfluidic chip.

Three-dimensional (3D) temperature mapping method with high spatial resolution and acquisition rate is of vital importance in evaluating thermal processes in micro-environment. We have synthesized a new temperature-sensitive functional material (Rhodamine B functionalized Polydimethylsiloxane). By performing optical sectioning of this material, we established an advanced method for visualizing the micro-scale 3D thermal distribution inside microfluidic chip with down to 10 ms temporal resolution and 2 ~ 6 °C temperature resolution depending the capture parameters. This method is successfully applied to monitor the local temperature variation throughout micro-droplet heat transfer process and further reveal exothermic nanoliter droplet reactions to be unique and milder than bench-top experiment.

A facile method for synthesis of N-doped ZnO mesoporous nanospheres and enhanced photocatalytic activity.

A facile synthesis route is reported for preparation of N-doped mesoporous ZnO nanospheres by a solvothermal treatment of Zn(NO3)2·6H2O which provides a source of both zinc and nitrogen. A variety of different spectroscopic and analytical techniques, such as powder X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis and X-ray photoelectron (XPS) spectroscopies were used to characterize the physicochemical properties of catalysts. The photocatalytic activities of the composites were evaluated by the degree of degradation of rhodamine B in aqueous solutions at room temperature with near-UV light irradiation. These nanocomposites exhibit higher photocatalytic activity compared with pure ZnO nanoparticles. The enhancement of photocatalytic activity of N-doped ZnO nanoparticles is mainly attributed to their absorption of more photons and reduced electron-hole pair recombination. Our one-step, environmentally friendly synthetic method may provide a new means of designing and synthesizing series of N-doped metal oxide semiconductors for use in photo-assisted catalytic reactions.

Efficient photocatalytic activity with carbon-doped SiO2 nanoparticles.

Photocatalysis provides a 'green' approach to completely eliminate various kinds of contaminants that are fatal for current environmental and energy issues. Semiconductors are one of the most frequently used photocatalysts as they can absorb light over a wide spectral range. However, it is also well known that naked SiO2 is not an efficient photocatalyst due to its relatively large band gap, which could only absorb shortwave ultraviolet light. In this report, nanoscale particles of carbon-doped silicon dioxide (C-doped SiO2) for use in photocatalysis were successfully prepared by a facile one-pot thermal process using tetraethylorthosilicate (TEOS) as the source of both silicon and carbon. These particles were subsequently characterized by thermogravimetric analysis, X-ray diffraction, standard and high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The C-doped SiO2 displayed outstanding photocatalytic properties, as evidenced by its catalysis of Rhodamine B degradation under near-UV irradiation. We propose that carbon doping of the SiO2 lattice creates new energy states between the bottom of the conduction band and the top of the valence band, which narrows the band gap of the material. As a result, the C-doped SiO2 nanoparticles exhibit excellent photocatalytic activities in a neutral environment. The novel synthesis reported herein for this material is both energy efficient and environmentally friendly and as such shows promise as a technique for low-cost, readily scalable industrial production.

High quality self-assembly magnetite (Fe(3)O(4)) chain-like core-shell nanowires with luminescence synthesized by a facile one-pot hydrothermal process.

Large scale synthesis of uniform self-assembly Fe(3)O(4)@phenol formaldehyde resin (PFR) core-shell nanowires with 80-100 nm in diameter and 20-30 microm in length can be realized by a one-pot hydrothermal process. The optical and magnetic properties of the as-synthesized Fe(3)O(4) nanostructures have been investigated.

Surfactant-controlled synthesis of Fe nanorods in solution.

Rodlike Fe particles were prepared by reduction of iron salts with hydrazine hydrate in the presence of CTAB. The as-prepared powders were characterized in detail by conventional techniques such as X-ray diffraction, and scanning electron microscopy, and their magnetic properties were evaluated on a vibrating sample magnetometer.