Enhancing the performance of aqueous zinc ion battery cathodes with a floral spherical V5O12·6H2O/V6O13/CNT nanocomposite.

Aqueous zinc ion batteries (AZIBs) offer a promising approach for electrical energy storage, combining cost-effectiveness and enhanced thermal safety. However, the cathode material, vanadium oxide, while known for its excellent theoretical specific capacity, faces a challenge in terms of its poor electronic conductance. In this study, we present a novel strategy to address this limitation by constructing the V5O12·6H2O/V6O13/CNT (VOH/CNT) nanocomposite, resulting in significantly improved electrochemical performance. This nanocomposite was synthesized through a facile solvothermal method, yielding a unique floral spherical structure featuring a central cluster and multiple smaller groupings. The integration of CNTs into the composite significantly enhanced its electronic conductance, effectively mitigating the electronic conductance issue associated with vanadium oxide. Moreover, the composite retains crystalline water within its structure, playing a crucial role in providing a favorable ion-conductive pathway. Consequently, the VOH/CNT nanocomposite exhibits an impressive reversible capacity of 201 mA h g-1 at 50 mA g-1, surpassing that of VOH (116 mA h g-1). Remarkably, even at a high current density, the VOH/CNT nanocomposite demonstrates an exceptional capacity retention, maintaining a capacity of 150 mA h g-1 over 500 cycles at 1 A g-1. Its outstanding electrochemical performance can be attributed to its distinctive structural arrangement, the conductive network facilitated by CNTs, and the introduced crystalline water component.

Centrosymmetric Thiophenemethyleneoxindole-Based Donor-Acceptor Copolymers for Organic Field-Effect Transistors.

Two novel, donor-acceptor-type π-conjugated polymers (P1 and P2) with 3'-(thieno[3,2-b]thiophene-2,5-diylbis(methan-1-yl-1-ylidene))bis-(indolin-2-one) (ITTI) as the acceptor and thiophene/bithiophene as the donor are designed and synthesized by palladium-catalyzed Stille coupling. The optical and electrochemical properties of these polymers are characterized and further implemented into organic field-effect transistors (OFET). Both polymers exhibit excellent thermal stability, broad UV-vis absorption, and high highest occupied molecular orbital energy levels. Thermal annealing induces a well-ordered structure, a highly planar π-system (oxygen-sulfur interaction), and a bathochromic shift in the polymers; furthermore, significant enhancement of the long wavelength intensity is also observed. Both polymers exhibit p-type charge transport behavior, with hole mobilities up to 0.51 cm2 V-1 s-1 for P1 and 0.65 cm2 V-1 s-1 for P2. This work demonstrates that ITTI can be a promising building block for the construction of donor-acceptor polymers with high-performance OFETs.

Molybdenum/selenium based heterostructure catalyst for efficient hydrogen evolution: Effects of ionic dissolution and repolymerization on catalytic performance.

Transition metal chalcogenides (TMCs) are recognized as highly efficient electrocatalysts and have wide applications in the field of hydrogen production by electrolysis of water, but the real catalytic substances and catalytic processes of these catalysts are not clear. The species evolution of Mo and Se during alkaline hydrogen evolution was investigated by constructing MoSe2@CoSe2 heterostructure. The real-time evolution of Mo and Se in MoSe2@CoSe2 was monitored using in situ Raman spectroscopy to determine the origin of the activity. Mo and Se in MoSe2@CoSe2 were dissolved in the form of MoO42- and SeO32-, respectively, and subsequently re-adsorbed and polymerized on the electrode surface to form new species Mo2O72- and SeO42-. Theoretical calculations show that adsorption of Mo2O72- and SeO42- can significantly enhance the HER catalytic activity of Co(OH)2. The addition of additional MoO42- and SeO32- to the electrolyte with Co(OH)2 electrodes both enhances its HER activity and promotes its durability. This study helps to deepen our insight into mechanisms involved in the structural changes of catalyst surfaces and offers a logical basis for revealing the mechanism of the influence of species evolution on catalytic performance.

Synergistic Effect of P Doping and Mo-Ni-Based Heterostructure Electrocatalyst for Overall Water Splitting.

Heterostructure construction and heteroatom doping are powerful strategies for enhancing the electrolytic efficiency of electrocatalysts for overall water splitting. Herein, we present a P-doped MoS2/Ni3S2 electrocatalyst on nickel foam (NF) prepared using a one-step hydrothermal method. The optimized P[0.9mM]-MoS2/Ni3S2@NF exhibits a cluster nanoflower-like morphology, which promotes the synergistic electrocatalytic effect of the heterostructures with abundant active centers, resulting in high catalytic activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolyte. The electrode exhibits low overpotentials and Tafel slopes for the HER and OER. In addition, the catalyst electrode used in a two-electrode system for overall water splitting requires an ultralow voltage of 1.42 V at 10 mA·cm-2 and shows no obvious increase in current within 35 h, indicating excellent stability. Therefore, the combination of P doping and the heterostructure suggests a novel path to formulate high-performance electrocatalysts for overall water splitting.

Hydrogen-Bonded Colorimetric and Fluorescence Chemosensor for Fluoride Anion With High Selectivity and Sensitivity: A Review.

In recent years, the wide application of fluoride materials has grown rapidly, therefore excessive discharge in the surrounding environment, especially in drinking water and organic effluent, has become a potential hazard to humans, and has even resulted in fluorosis disease. The development of a highly effective and convenient method to recognize fluoride anions in surrounding environments seems necessary and urgent. Among which, the development of a colorimetric and fluorescence fluoride chemosensor with obvious color changing allowing for naked-eye detection with high sensitivity and selectivity is more interesting and challenging. In this minireview, current novel colorimetric and fluorescence chemosensors for fluoride anions by hydrogen-bond interaction are introduced, including obvious color changing by naked-eye detection, high sensitivity and selectivity, non-pollution and fluoride extraction ability, aqueous detection, and other additional functions. Finally, the perspective of the fluoride chemosensor design concept and potential evolution trends are pointed out.

Microstructure and Properties of Ag-Doped ZnO Grown Hydrothermally on a Graphene-Coated Polyethylene Terephthalate Bilayer Flexible Substrate.

Ag-doped ZnO nanorods growth on a PET-graphene substrate (Ag-ZnO/PET-GR) with different Ag-doped content were synthesized by low-temperature ion-sputtering-assisted hydrothermal synthesis method. The phase composition, morphologies of ZnO, and electrical properties were analyzed. Ag-doping affects the initially perpendicular growth of ZnO nanorods, resulting in oblique growth of ZnO nanorods becoming more obvious as the Ag-doped content increases, and the diameter of the nanorods decreasing gradually. The width of the forbidden band gap of the ZnO films decreases with increasing Ag-doped content. For the Ag-ZnO/PET-GR composite structure, the Ag-ZnO thin film with 5% Ag-doped content has the largest carrier concentration (8.1 × 1018 cm-3), the highest mobility (67 cm2 · V-1 · s-1), a small resistivity (0.09 Ω·cm), and impressive electrical properties.

Crystallization and Microstructure Evolution of Microinjection Molded Isotactic Polypropylene with the Assistance of Poly(Ethylene Terephthalate).

In this work, a series of isotactic polypropylene/poly(ethylene terephthalate) (iPP/PET) samples were prepared by microinjection molding (µIM) and mini-injection molding (IM). The properties of the samples were investigated in detail by differential scanning calorimetry (DSC), Wide-Angle X-ray Diffraction (WAXD), Polarized light microscope (PLM) and scanning electron microscopy (SEM). Results showed that the difference in thermomechanical history between both processing methods leads to the formation of different microstructures in corresponding iPP/PET moldings. For example, the dispersed spherical PET phase deforms and emerges into continuous in-situ microfibrils due to the intensive shearing flow field and temperature field in µIM. Additionally, the incorporation of PET facilitates both the laminar branching and the reservation of oriented molecular chains, thereby leading to forming a typical hybrid structure (i.e., fan-shaped ß-crystals and transcrystalline). Furthermore, more compact and higher degrees of oriented structure can be obtained via increasing the content of PET. Such hybrid structure leads to a remarkable enhancement of mechanical property in terms of µIM samples.

Microscale Self-Assembly of Upconversion Nanoparticles Driven by Block Copolymer.

Lanthanide-based upconversion nanoparticles can convert low-energy excitation to high-energy emission. The self-assembled upconversion nanoparticles with unique structures have considerable promise in sensors and optical devices due to intriguing properties. However, the assembly of isotropic nanocrystals into anisotropic structures is a fundamental challenge caused by the difficulty in controlling interparticle interactions. Herein, we report a novel approach for the preparation of the chain-like assemblies of upconversion nanoparticles at different scales from nano-scale to micro-scale. The dimension of chain-like assembly can be fine-tuned using various incubation times. Our study observed Y-junction aggregate morphology due to the flexible nature of amphiphilic block copolymer. Furthermore, the prepared nanoparticle assemblies of upconversion nanoparticles with lengths up to several micrometers can serve as novel luminescent nanostructure and offer great opportunities in the fields of optical applications.

Interface engineering of NiV-LDH@FeOOH heterostructures as high-performance electrocatalysts for oxygen evolution reaction in alkaline conditions.

A hybrid heterostructure eletrocatalyst supported on Ni foam is facilely synthesized as a high-performance OER electrocatalyst for alkaline water electrolysis. Compared to their pristine NiV-LDH counterpart, the self-made NiV-LDH@FeOOH heterostructures exhibit an extremely low overpotential of ∼297 mV at 100 mA cm-2 current output, and excellent long-term durability.

Tribological Properties of Mo-Si-B Alloys Doped with La2O3 and Tested at 293-1173 K.

According to the stoichiometric ratios of Mo-10Si-7B, Mo-12Si-8.5B, Mo-14Si-9.8B, and Mo-25Si-8.5B, some new Mo-Si-B alloys doped with 0.3 wt % lanthanum (III) oxide (La2O3) were prepared via liquid-liquid (L-L) doping, mechanical alloying (MA), and hot-pressing (HP) sintering technology. The phase-composition and microstructure were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The worn surfaces of the plate specimens were studied by confocal laser scanning microscopy (CLSM). Then, the tribological properties of Mo-Si-B alloy doped with sliding plate specimens of 0.3 wt % La2O3 were investigated against the Si3N4 ball specimens. The friction coefficients of Mo-Si-B alloys decreased and the wear rates of the alloys increased with test load. The high-temperature friction and wear behavior of Mo-Si-B alloy are related to the surface-oxidation and contact-deformation of the alloy at a high temperature. The low friction coefficients and the reduced wear rates are thought to be due to the formation of low friction MoO3 films. MoO3 changed the contact state of the friction pairs and behaved as lubricating films.

Conjugated Polymers Containing Building Blocks 1,3,4,6-Tetraarylpyrrolo[3,2-b]pyrrole-2,5-dione (isoDPP), Benzodipyrrolidone (BDP) or Naphthodipyrrolidone (NDP): A Review.

π-Conjugated organic donor-acceptor (D-A) type polymers are widely developed and used in electronic device. Among which, diketopyrrolopyrrole (DPP)-based polymers have received the most attention due to their high performances. The novel chromophores named 1,3,4,6-tetraarylpyrrolo[3,2-b]pyrrole-2,5-dione (isoDPP), benzodipyrrolidone (BDP) and naphthodipyrrolidone (NDP) are resemble DPP in chemical structure. IsoDPP is an isomer of DPP, with the switching position of carbonyl and amide units. The cores of BDP and NDP are tri- and tetracyclic, whereas isoDPP is bicyclic. π-Conjugation extension could result polymers with distinct optical, electrochemical and device performance. It is expected that the polymers containing these high-performance electron-deficient pigments are potential in the electronic device applications, and have the potential to be better than the DPP-based ones. IsoDPP, BDP, and NDP based polymers are synthesized since 2011, and have not receive desirable attention. In this work, the synthesis, properties (optical and electrochemical characteristics), electronic device as well as their relationship depending on core-extension or structure subtle optimization have been reviewed. The final goal is to outline a theoretical scaffold for the design the D-A type conjugated polymers, which is potential for high-performance electronic devices.

Electrical and photocatalytic properties of boron-doped ZnO nanostructure grown on PET-ITO flexible substrates by hydrothermal method.

Boron-doped zinc oxide sheet-spheres were synthesized on PET-ITO flexible substrates using a hydrothermal method at 90 °C for 5 h. The results of X-ray diffraction and X-ray photoelectron spectroscopy indicated that the B atoms were successfully doped into the ZnO lattice, the incorporation of B led to an increase in the lattice constant of ZnO and a change in its internal stress. The growth mechanism of pure ZnO nanorods and B-doped ZnO sheet-spheres was specifically investigated. The as-prepared BZO/PET-ITO heterojunction possessed obvious rectification properties and its positive turn-on voltage was 0.4 V. The carrier transport mechanisms involved three models such as hot carrier tunneling theory, tunneling recombination, and series-resistance effect were explored. The BZO/PET-ITO nanostructures were more effective than pure ZnO to degrade the RY 15, and the degradation rate reached 41.45%. The decomposition process with BZO nanostructure followed first-order reaction kinetics. The photocurrent and electrochemical impedance spectroscopy revealed that the B-doping could promote the separation of photo-generated electron-hole pairs, which was beneficial to enhance the photocatalytic activity. The photocurrent density of B-doped and pure ZnO/PET-ITO were 0.055 mA/cm2 and 0.016 mA/cm2, respectively. The photocatalytic mechanism of the sample was analyzed by the energy band theory.

The Flexural Strength and Fracture Toughness of TC4-Based Laminated Composites Reinforced with Ti Aluminide and Carbide.

TiC-Ti-Al mixed powders and TC4 titanium alloy foils were overlapped layer-by-layer in the graphite die. The TC4-based laminated composite sheets reinforced by Ti aluminide and carbide were successfully fabricated via spark plasma sintering (SPS) at 1100 °C with a well-bonded interface. The composite layers were mainly composed of TiAl, Ti3Al, Ti2AlC, and Ti3AlC2 phases. The carbides particles distributed in the matrix played an important role in the deflection of cracks and the passivation of microcracks. TC4 titanium alloy layers had an obvious effect on the stress distribution during the loading process, and provided an energy dissipation mechanism, which could improve the mechanical properties of the laminated composite sheets obviously. When the theoretical amount of Ti2AlC was 20 wt %, the flexural strength and fracture toughness of the laminated composite sheets reached the maximum value in the arrester direction, which were 1428.79 MPa and 64.08 MPa·m1/2, respectively.