Latest ArticlesBacterial infection is currently a serious challenge globally, causing death of thousands of human beings. New antimicrobial agents with novel mechanism of action are urgently needed. Transition metal complexes have shown great potentials in photodynamic and photocatalytic therapy. Herein, we take full advantage of metal photocatalyst and successfully developed a novel cyclometalated iridium(Ⅲ) complex (Ir1) with higher biofilm damage efficiency than the clinical antibiotics. Ir1 synergistically generates reactive oxygen species and coenzyme photocatalytic activity with high efficiency under white light irradiation. Combined with these properties, Ir1 exhibited excellent photoinactivation of S. aureus and effectively damaged the biofilm. This work provides a new approach for the development of antibacterial photodynamic therapy.
In recent years, biochar (BC) as a low-cost, easily available biomass product, is widely applied in sulfate radical-based advanced oxidation processes (SR-AOPs) for emerging pollutants remediation. Herein, a state-of-art review of iron-based biochar catalysts is currently available in SR-AOPs application. A general summary of the development of biochar and the catalytic properties of biochar is presented. Especially, the synthetic strategies of different types of iron-based biochar catalysts are discussed. Moreover, the theoretical calculation to interpret the interaction between biochar and iron species is discussed to explore the activation mechanisms. And the regeneration methods of biochar-based catalyst are presented. The unresolved challenges of the existent biochar-based SR-AOPs are pointed out, and the outlooks of future research directions are proposed.
The sluggish conversion kinetics and shuttle effect of lithium polysulfides (LiPSs) severely hamper the commercialization of lithium–sulfur batteries. Numerous electrocatalysts have been used to address these issues, amongst which, transition metal dichalcogenides have shown excellent catalytic performance in the study of lithium–sulfur batteries. Note that dichalcogenides in different phases have different catalytic properties, and such catalytic materials in different phases have a prominent impact on the performance of lithium–sulfur batteries. Herein, 1T-phase rich MoSe2 (T-MoSe2) nanosheets are synthesized and used to catalyze the conversion of LiPSs. Compared with the 2H-phase rich MoSe2 (H-MoSe2) nanosheets, the T-MoSe2 nanosheets significantly accelerate the liquid phase transformation of LiPSs and the nucleation process of Li2S. In-situ Raman and X-ray photoelectron spectroscopy (XPS) find that T-MoSe2 effectively captures LiPSs through the formation of Mo-S and Li-Se bonds, and simultaneously achieves fast catalytic conversion of LiPSs. The lithium–sulfur batteries with T-MoSe2 functionalized separators display a fantastic rate performance of 770.1 mAh/g at 3 C and wonderful cycling stability, with a capacity decay rate as low as 0.065% during 400 cycles at 1 C. This work offers a novel perspective for the rational design of selenide electrocatalysts in lithium–sulfur chemistry.
A pair of selenanthrene-bridged molecular cages have been constructed through a one-step cyclization reaction of a tetrakis(iodo) crown ether with selenium powder. The tubular belt-shaped cage has an intrinsic cavity which can adaptively transform to accommodate electron-deficient guests forming [2]pseudorotaxane complexes. The other product was determined to be an isomeric cage featuring a Möbius strip structure, which exhibits slower twist-migration dynamics than its thianthrene counterpart. The success of using selenanthrene as joints enables an alternative way to structural design and property regulation of molecular cages.
Li2ZrCl6 (LZC) solid-state electrolytes (SSEs) have been recognized as a candidate halide SSEs for all-solid-state Li batteries (ASSLBs) with high energy density and safety due to its great compatibility with 4 V-class cathodes and low bill-of-material (BOM) cost. However, despite the benefits, the poor chemical/electrochemical stability of LZC against Li metal causes the deterioration of Li/LZC interface, which has a detrimental inhibition on Li+ transport in ASSLBs. Herein, we report a composite SSE combining by LZC and argyrodite buffer layer (Li6PS5Cl, LPSC) that prevent the unfavorable interaction between LZC and Li metal. The Li/LPSC-LZC-LPSC/Li symmetric cell stably cycles for over 1000 h at 0.3 mA/cm2 (0.15 mAh/cm2) and has a high critical current density (CCD) value of 2.1 mA/cm2 at 25 ℃. Under high temperature (60 ℃) which promotes the reaction between Li and LZC, symmetric cell fabricated with composite SSE also display stable cycling performance over 1200 h at 0.3 mAh/cm2. Especially, the Li/NCM ASSLBs fabricated with composite SSE exhibit a high initial coulombic efficiency, as well as superior cycling and rate performance. This simple and efficient strategy will be instrumental in the development of halide-based high-performance ASSLBs.
Nanocarriers play an important role in drug delivery for disease treatment. However, nanocarriers face a series of physiological barriers after administration such as blood clearance, nonspecific tissue/cell localization, poor cellular uptake, and endosome trapping. These physiological barriers seriously reduce the accumulation of drugs in target action site, which results in poor therapeutic efficiency. Although polyethylene glycol (PEG) can increase the blood circulation time of nanocarriers, its application is limited due to the "PEG dilemma". Zwitterionic polymers have been emerging as an appealing alternative to PEG owing to their excellent performance in resisting nonspecific protein adsorption. Importantly, the diverse structures bring functional versatility to zwitterionic polymers beyond nonfouling. This review focuses on the structures and characters of zwitterionic polymers, and will discuss and summarize the application of zwitterionic polymers for drug delivery. We will highlight the strategies of zwitterionic polymers to address the physiological barriers during drug delivery. Finally, we will give some suggestions that can be utilized for the development of zwitterionic polymers for drug delivery. This review will also provide an outlook for this field. Our aim is to provide a comprehensive and systemic review on the application of zwitterionic polymers for drug delivery and promote the development of zwitterionic polymers.
Distortion of planar aromatics occurs in the fused rings conjugated with bulky substituents, which generates racemic enantiomers with high transformation energy barriers. However, direct synthesis of homochiral distorted aryl compounds is a very challenging task. Here, we presented a molecular folding strategy to control distorted aryl homochirality. Amino acids and their derivatives conjugated on the polycyclic aromatic hydrocarbons including benzenes, naphthalenes and triphenylenes, which formed parallel β-sheet arrays through intramolecular hydrogen bonds. The folding behavior enabled distorted or twisted geometry of aromatics, of which the handedness was associated with the absolute chirality of amino acids. X-ray crystallography, theoretical calculations and circular dichroism spectroscopy verified the distorted homochirality in the solid and solution phase. The relatively small rotational barrier between the enantiomers made the molecule sensitive to the environment and thus realized the solvent-controlled chiral inversion. The β-sheet folding strategy can be widely used in polycyclic aromatic hydrocarbons with various functions, which provided a promising strategy to control inherent chirality of aromatics with adaptive chiroptical responses.
The d-band centers of catalysts have exhibited excellent performance in various reactions. Among them, the enhanced catalytic reaction is considered a crucial way to power dynamics and reduce the "shuttle" effect in polysulfide conversions of lithium-sulfur batteries. Here, we report two-dimensional-shaped tungsten borides (WB) nanosheets with d-band centers, where the d orbits of W atoms on the (001) facets show greatly promoting the electrocatalytic sulfur reduction reaction. As-prepared WB-based Li-S cells exhibit excellent electrochemical performance for Li-ion storage. Especially, it delivers superior capacities of 7.7 mAh/cm2 under the 8.0 mg/cm2 sulfur loading, which is far superior to most other electrode catalysts. This study provides insights into the d-band centers as a promising catalyst of two-dimensional boride materials
In this work, taking NiSe2 as a prototype to be used as cocatalyst in photocatalytic hydrogen evolution, we demonstrate that the crystal phase of NiSe2 plays a vital role in determining the catalytic stability, rather than activity. Theoretical and experimental results indicate that the phase structure shows negligible influence to the charge transport and hydrogen adsorption capacity. When integrating with carbon nitride (CN) photocatalyst forming hybrids (m-NiSe2/CN and p-NiSe2/CN), the hybrids show comparable photocatalytic hydrogen evolution rates (3.26 µmol/h and 3.75 µmol/h). Unlike the comparable catalytic activity, we found that phase-engineered NiSe2 exhibits distinct stability, i.e., m-NiSe2 can evolve H2 steadily, but p-NiSe2 shows a significant decrease in catalytic process (~57.1% decrease in 25 h). The factor leading to different catalytic stability can be ascribed to the different surface conversion behavior during photocatalytic process, i.e., chemical structure of m-NiSe2 can be well preserved in catalytic process, but partial p-NiSe2 tends to be converted to NiOOH.
Spectroscopic study of water splitting by neutral metal clusters is crucial to understanding the microscopic mechanism of catalytic processes but has been proven to be a challenging experimental target due to the difficulty in size selection. Here, we report a size-specific infrared spectroscopic study of the reactions between neutral group 3 metals and water molecules based on threshold photoionization using a vacuum ultraviolet laser. Quantum chemical calculations were carried out to identify the structures and to assign the experimental spectra. All the M2O4H4 (M = Sc, Y, La) products are found to have the intriguing M2(μ2-O)(μ2-H)(μ2-OH)(η1-OH)2 structures, indicating that the HOH bond breaking, the MO/MH/MOH bond formation, and hydrogen production proceed efficiently in the reactions between laser-vaporized metals and water molecules. The joint experimental and theoretical results on the atomic scale demonstrate that the water splitting by neutral group 3 metals is both thermodynamically exothermic and kinetically facile in the gas phase. These findings have important implications for unravelling the structure-reactivity relationship of catalysts with isolated metal atoms/clusters dispersed on supports.
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