Latest ArticlesConstruction of proton transport channels in metal-organic frameworks (MOFs) with simple synthesis processes, high proton conductivities and good performance stabilities has been of great interest for proton exchange membrane fuel cell (PEMFC). Herein, we mimic the proton transport behavior of amino acid residues in bacteriorhodopsin, select UiO-66-COOH as the host, glycine and aspartic acid as the functional guest molecules, and then functionalize the MOF framework with amino acids to obtain biomimetic proton transport channels. This strategy endows UiO-66-COOH-Asp a high proton conductivity of 1.19 × 10−2 S/cm at 70 ℃ and 98% RH, excellent cycle stability of performances and performance durability, which can be comparable to the reported MOFs-based proton conductors. Moreover, the proton conduction mechanism in UiO-66-COOH-Asp is elaborated in detail due to its visual structure, which is also one of the advantages of adopting MOFs as research platform, making it possible to optimize the structure-activity relationship of advanced materials. Notably, this strategy has clear objectives and simple synthesis, which has made certain contributions to both theoretical research and future industrial production of proton conductors.
The intimate host-anion interactions will regulate thermodynamics and kinetics in the self-assembly of cationic cages mimicking biological counterparts. Herein, we report construction and transformation of three Pd(Ⅱ)-based metal-organic cages (MOCs) depending on different anions. Stoichiometric conversions of the lantern-shaped MOC-34 into either octahedral MOC-35 or tricapped trigonal prism MOC-36 are induced by BF4‒ or NO3‒, respectively. MOC-36 is kinetically favored and can undergo quantitative conversion to the thermodynamically preferred MOC-35 upon heating, accelerated by excess BF4‒ to motivate dissociative dynamics of Pd-vertices and lower activation barrier of cage transformation. The guest encapsulation behaviors of MOC-35 and MOC-36 have also been tested. These results manifest a significance of host-anion dynamics beyond complementary anion template, shedding light on the understanding of intricate anion recognition in nature.
A new, four component copper(Ⅰ)-catalyzed interrupted click/radical relay cascade has been developed. This unprecedented interrupted click reaction provides a rapid modular synthesis of triazole sulfones, important privileged heterocyclic pharmacophores which cannot be accessed by a traditional click reaction. Radical interception of cuprate-triazole, the key reaction intermediate formed in situ, is an important feature of this process.
Carbon dots (CDs) have been extensively studied owing to their fascinating optical properties and wide potential applications. Here, we report an easy-to-perform and organic-solvent-free synthesis strategy for green-emissive CDs (G-CDs) possessing high photoluminescence (PL) quantum yield (QY). The G-CDs are synthesized by heating the homogeneous precursors of citric acid and cyanamide in an open vessel, circumventing the use of organic solvents, complex operations, high-pressure reactors, and expensive instruments in the synthesis process. The effect of various reaction variables on the formation and the optical properties of G-CDs are systematically investigated. The resultant G-CDs show bright PL emission at 521 nm with PL QY up to 73%. Then a white light-emitting diode (LED) with Commission Internationable de L'Eclairage (CIE) coordinates of (0.33, 0.34) and color rendering index (CRI) of 92 is constructed based on G-CDs/thermoplastic polyurethane (TPU) composite. Moreover, a visual microfluidic detection platform is designed by using G-CDs as fluorescent probes for rapid quantitative detection of Fe3+, Cu2+, and Mn2+ metal ions, which can realize synchronized testing of multiple samples. This study might promote the development and preparation methods of high-performance CDs with various optical applications.
Poly(ethylene oxide) (PEO) polymer electrolytes (PEs) have been commercially applied in LiFePO4||Li solid-state lithium batteries (SSLBs). However, it remains challenging to develop PEO-based PEs applicable to the high-voltage SSLBs with higher energy density, owing to the poor electrochemical stability of PEO. Herein, we report a scalable strategy for fabricating PEO-based PEs with high-voltage compatibility, by exploiting a new mechanism to stabilize the cathode-electrolyte interface in the high-voltage SSLBs. The protocol only involves a one-pot synthesis procedure to covalently crosslink the PEO chains, in the presence of high-content lithium bis(trifluoromethylsulphonyl)imide (LiTFSI) salts and N,N-dimethylformamide (DMF). LiTFSI-DMF supramolecular aggregates are formed and firmly embedded in the polymer network, endowing the PE with high room-temperature ionic conductivity. The dissociated and highly concentrated TFSI− anions can enter the Helmholtz layer close to the high-voltage cathode, leading to the formation of a thin and homogeneous cathode electrolyte interface (CEI), mainly composed of LiF, on the cathode. The CEI with high electrochemical stability can effectively stabilize the cathode-electrolyte interface, enabling long-term stable cycling of the high-voltage LiCoO2||Li and nickel-rich NCM622||Li batteries at room temperature. The simplicity and scalability of the strategy makes the reported PEO-based PE potentially applicable in high-voltage SSLBs in practice.
The controllable morphology and composition of catalysts are crucial to improving the electrocatalytic activity of oxygen evolution reaction (OER). Herein, we construct a bimetallic heterostructure by sulfidation and hydrothermal methods, and the layered ReS2 is vertically aligned on Prussian blue-derived hollow Co9S8 nanocubes (Co9S8@ReS2). The core-shell structure of Co9S8@ReS2 can effectively prevent the restacking of layered ReS2, expose the abundant surface area and improve the utilization of electrocatalytic sites, resulting in fast electrolyte diffusion and charge transfer during OER. Due to the synergistic effect of the core-shell morphology and the formed bimetallic heterostructure, Co9S8@ReS2 exhibits excellent catalytic OER performance. At 10 mA/cm2, only 288 mV of overpotential is required with the Tafel slope of 73.3 mV/dec for Co9S8@ReS2, which are both lower than that of Co9S8 and ReS2. Meanwhile, Co9S8@ReS2 exhibits high catalytic stability and low charge transfer resistance and the boosted active sites are confirmed by density functional theory. This work provides a rational design of the OER catalysts by constructing the bimetallic heterostructure.
The intricate correlation between multiple degrees of freedom and physical properties is a fascinating area in solid state chemistry and condensed matter physics. Here, we report a quantum-magnetic system BaNi2V2O8 (BNVO), in which the spin correlation was modulated by unusual oxidation state, leading to different magnetic behavior. The BNVO was modified with topochemical reduction (TR) to yield TR-BNVO with partially reduced valance state of Ni+ in the two-dimensional NiO6-honeycomb lattice. Accordingly, the antiferromagnetic order is suppressed by the introduction of locally interposed Ni+ and oxygen vacancies, resulting in a ferromagnetic ground state with the transition temperature up to 710 K. A positive magnetoresistance (7.5%) was observed in the TR-BNVO at 40 K under 7 T. These findings show that topological reduction is a powerful approach to engineer low-dimensional materials and accelerate the discovery of new quantum magnetism.
Two 3d-4f-5d heterometallic cluster-containing polyoxometalates, formulated as Na22{(SbW9O33)4[La3W6MO18(H2O)8(CH3COO)4]2}·nH2O (abbreviated as La6M2, M = Co/Mn) were synthesized and structurally characterized. Single-crystal X-ray diffraction analyses reveal that the polyanions of La6Co2 and La6Mn2 consist of the uncommon 3d-4f-5d clusters {La6W12Co2} and {La6W12Mn2}, which are encapsulated by four trilacunary Keggin tungstoantimonates to form the parallelogram-shaped title compounds. Additionally, the polyanions can be extended into a two-dimensional (2D) frame by the linkage of peripheral Na+ ions. The inner space of the 2D layer was filled with water molecules and thus an H-bonded network was formed, which is expected to exhibit a fascinating proton conductivity. The study of water-assisted proton conduction demonstrated that La6Co2 and La6Mn2 were temperature- and humidity-dependent proton conductors, respectively, and the proton conductivities could reach 1.3 × 10−2 and 2.3 × 10−2 S/cm at 65 ℃ and 90% RH conditions.
Flexible aqueous zinc-ion batteries (AZIBs) with air-recharging capability are a promising self-powered system applied in future wearable electronics. It is desired to develop high-capacity air-rechargeable AZIBs. Herein, we developed a flexible AZIB with air-recharging capability based on trinitrohexaazatrinaphthylene (TNHATN) cathode and a ZnSO4 electrolyte. The flexible Zn//TNHATN battery exhibits high volumetric energy density (21.36 mWh/cm3) and excellent mechanical flexibility. Impressing, the discharged flexible Zn//TNHATN battery can be chemical self-charged via the redox reaction between TNHATN cathode and O2 from the air. After oxidation in air for 15 h, such flexible Zn//TNHATN battery can deliver a high specific capacity of 320 mAh/g at 0.5 A/g, displaying excellent air-recharging capability. Notably, this flexible Zn//TNHATN battery also works well in chemical or/and galvanostatic charging mixed modes, showing reusability. This work provides a new insight for designing flexible aqueous self-powered systems.
Fungal symbionts co-evolve with hosts and microbial co-inhabitants to acquire an unpredictable potential for producing novel bioactive metabolites, but the knowledge about the topic remains patchy and superficial. Here we present the chemical characterization of acatulides A−G (1−7) as architecturally unprecedented macrolides from the solid-state culture of Acaulium album H-JQSF, an arthropod-associated fungus. The acatulide structures were elucidated by spectroscopic analysis, modified Mosher's method and single-crystal X-ray diffraction. The plausible biosynthetic pathways for compounds 1−4 are proposed. Interestingly, acatulides B−D (2−4) and G (7) were demonstrated to be neuroprotective against the 1-methyl-4-phenylpyridinium (MPP+)-induced damage to SH-SY5Y cells and nematode Caenorhabditis elegans (C. elegans).
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