Latest ArticlesFabrication of selective adsorption coatings plays a crucial role in solid-phase microextraction (SPME). Herein, new strategies were developed for the in-situ fabrication of novel cobalt-based carbonaceous coatings on the nickel-titanium alloy (NiTi) fiber substrate using ZIF-67 as a precursor and template through the chemical reaction of ZIF-67 with glucose, dopamine (DA) and melamine, respectively. The adsorption performance of the resulting coatings was evaluated using representative aromatic compounds coupled to high-performance liquid chromatography (HPLC) with ultraviolet detection (HPLC-UV). The results clearly demonstrated that the adsorption selectivity was subject to the surface elemental composition of the fiber coatings. The cobalt and nitrogen co-doped carbonaceous coating showed better adsorption selectivity for ultraviolet filters. In contrast, the cobalt-doped carbonaceous coating exhibited higher adsorption selectivity for polycyclic aromatic hydrocarbons. The fabricated fibers present higher mechanical stability and higher adsorption capability for model analytes than the commercial polydimethylsiloxane and polyacrylate fibers. These new strategies will continue to expand the NiTi fibers as versatile fiber substrates for metal-organic frameworks (MOFs)-derived coating materials with controllable nanostructures and tunable properties.
The urgent need for immediate personal protection against chemical warfare agents (CWAs) spurs the requirement on robust and highly efficient catalytic systems that can be conveniently integrated to wearable devices. Herein, as a new concept for CWA decontamination catalyst design, sub-nanoscale, catalytically active zirconium-oxo molecular clusters are covalently integrated in flexible polymer network as crosslinkers for the full exposure of catalytic sites as well as robust framework structures. The obtained membrane catalysts exhibit high swelling ratio with aqueous content as 84 wt% and therefore, demonstrate quasi-homogeneous catalytic activity toward the rapid hydrolysis of both CWA, soman (GD) (t1/2 = 5.0 min) and CWA simulant, methyl paraoxon (DMNP) (t1/2 = 8.9 min). Meanwhile, due to the covalent nature of cross-linkages and the high flexibility of polymer strands, the membranes possess promising mechanical strength and toughness that can stand the impact of high gas pressures and show high permeation for both CO2 and O2, enabling their extended applications in the field of collective/personal protective materials with body comfort.
Well-defined two-dimensional (2D) cobalt oxalate (CoC2O4·2H2O) nanosheets exhibit more excellent property than common bulk cobalt oxalate due to high specific surface areas and high-efficient transport of ion and electron. However, the delicate control of the 2D morphology of CoC2O4·2H2O during their synthesis remains challenging. Herein, 2D CoC2O4·2H2O nanosheets (M1), grown by straightforward chemical precipitation, can be tuned from three-dimensional (3D) structure during their synthesis with no templates or capping agents. This control is obtained by rationally changing the ratio of reactants with ethylene glycol as solvent. Moreover, Co3O4/CoC2O4 composites (M1-250) have been fabricated through low-temperature thermal treatment of the M1 precursor in air, which possess porous surfaces with the 2D morphology maintained. Benefiting from the porous surfaces, more redox-active sites and better electrical conductivity of Co3O4, the constructed M1-250//AC aqueous device manifest improved kinetics of the electrochemistry process with energy density of 27.9 Wh/kg at 550.7 W/kg and good cycling stability with sustaining 73.0 mAh/g after 5000 cycles.
Silicon (Si) is regarded as the potential anode for lithium-ion batteries (LIBs), due to the remarkable theoretical specific capacity and low voltage plateau. However, the rapid capacity decay resulting from volume variation and slow electron/ion transportation of Si limit its practical application. Here, matryoshka-type carbon-stabilized hollow silicon spheres (Si/C/Si/C) are synthesized by an aluminothermic reduction and calcination process. The Si/C/Si/C anode materials prepared at 500 ℃ (Si/C/Si/C-500) exhibit unique structures, in which amorphous region and porous structure are preserved in the Si layers. The anode based on Si/C/Si/C-500 displays an initial specific capacity of 2792 mAh/g at a current density of 100 mA/g. At 1000 mA/g, this anode retains a reversible capacity of 1673 mAh/g, 86.9% of the initial capacity after 200 cycles. Such synthetic strategy can be employed to fabricate other high-capacity anode materials with large volume variation during charge/discharge process
Micro-nano-level photonic waveguide regulation is essential for future on-chip photonic integrated systems and is still of great challenges. We report a molecular design strategy, changing the position of the methyl substituent makes the arrangement of the three isomer molecules different in their respective crystals. Based on this strategy, three sheet-like crystals with different polygonal morphologies were prepared via solution self-assembly approach. The in-depth optical measurements demonstrated that these three microsheet crystals have different 2D optical waveguide performances related to the shapes. Our work provides a feasible design strategy and material preparation method for realizing precise 2D optical waveguide modulation, which lays the foundation for complex photonic integrated systems in the future.
The selection and development of cathode of alkaline zinc batteries (AZBs) is still hindered and often leads to poor rate capability and short cycle life. Here, amorphous hollow nickel-cobalt-based sulfides nanocages with nanosheet arrays (AM-NCS) are designed and constructed with ZIF-67 as the self-template to exchange with Ni2+ and S2− by using a two-step ion exchange method. The synthesized AM-NCS possess the high specific capacity (160 mAh/g at 2 A/g), and the assembled battery has excellent rate performance (146 mAh/g reversible capacity at 5 A/g). The assembled device has excellent rate performance (155 mAh/g at 2 A/g) and long cycling stability (7000 cycles, 62.5% of initial capacity). The excellent electrochemical properties of the electrode materials are mainly attributed to the unique structure, in particular, polyhedron structure with hollow structure can improve the cyclic stability, and the amorphous structure can expose more reactive sites on the surfaces of nickel, cobalt and sulfur. This work provides a new strategy for the design and fabrication of high performance cathode materials for AZBs.
Photodynamic therapy (PDT) has been gaining popularity in both scientific research and clinic applications due to its non-invasiveness and spatiotemporal targeting properties. Nevertheless, the local hypoxic microenvironment in tumor tissue impedes PDT universality. To overcome this drawback, a 2-pyridone-bearing BODIPY photosensitizer was synthesized rationally and introduced to polyethyleneglycol-b-poly(aspartic acid) to form a photosensitizer-1O2 generation, storage/release agent dual-loading system (PEG-b-PAsp-BODIPY). The investigation of the PDT effect at different illumination conditions in vitro and in vivo revealed that the system tremendously inhibited tumor proliferation, indicating that this new PEG-b-PAsp-BODIPY could act as a potentially effective photo therapeutic system for cancer therapeutics.
Metal-organic framework materials (MOFs), such as zeolitic imidazolate framework (ZIF), have been widely used in energy storage due to their advantages such as high structural stability, large specific surface, more active sites and skeleton structures. Herein, a novel two-dimensional (2D) CoCu-ZIF was synthesized by a facile solvothermal method. The as-prepared CoCu-ZIF nanosheets exhibit an ultrahigh reversible capacity of 2287.4 mAh/g and remains at 1172.1 mAh/g after 300 cycles at a current density of 100 mA/g, far better than that of the single Co-ZIF and Cu-ZIF. Additionally, the specific discharge capacity of CoCu-ZIF nanosheets can maintain at about 590 mAh/g after 1000 cycles at the current density of 2 A/g. Owing to the synergistic effect of two metals, function of nitrogen in the molecular and self-assembly 2D nanosheets, our research can provide strong support for the practical application of CoCu-ZIF materials in lithium ion batteries.
The simplification of localized surface plasmon resonance (LSPR) detection can further promote the development of optical biosensing application in point-of-care testing. In this study, we proposed a simple light emitting diode (LED) based single-wavelength LSPR sensor modulated with bio-electron transfers for the detection of electroactive biomolecules. Indium tin oxide electrode loaded with nanocomposites of polyaniline coated gold nanorod was used as LSPR chip, and the applied electric potential was scanned at the LSPR chip for single-wavelength LSPR biosensing. Under the scanning of applied potentials, biological electron transfer of redox reaction was employed to demonstrate the bioelectronic modulation of single-wavelength LSPR for selective electroactive biomolecule detection. Without any additional recognition material, electroactive biomolecules uric acid and dopamine were detected directly with a sensitivity of 5.05 μmol/L and 7.11 μmol/L at their specific oxidation potentials, respectively. With the simplified optical configuration and selective bioelectronic modulation, the single-wavelength LSPR sensor is promising for the development of simple, low-cost, and high specificity optical biosensor for point-of-care testing of electroactive biomolecules.
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