Latest ArticlesIn 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.
Uranium and molybdenum are important strategic elements. The production of 99Mo and the hydrometallurgical process of uranium ore face difficult problems of separation of uranium and molybdenum. In this study, the four phenanthroline diamide ligands were synthesized, and extraction and stripping experiments were performed under different conditions to evaluate the potential application of these ligands for separation of U(Ⅵ) over Mo(Ⅵ). With the growth of alkyl chain, the solubility of ligands could be greatly improved, and the separation effect of U(Ⅵ) over Mo(Ⅵ) gradually increased. The SFU/Mo were around 10,000 at 4 mol/L HNO3. Three stripping agents were tested with the stripping efficiency of Na2CO3 (5%) > H2O > HNO3 (0.01 mol/L). The stripping percentages of the three stripping agents were all close to unity, indicating that the ligands had the potential to be recycled. The chemical stoichiometry of U(Ⅵ) complexes with ligands was evaluated as 1:1 using electrospray ionization mass spectrometry, ultraviolet visible spectroscopy and single-crystal X-ray diffraction. The consistency between theoretical calculation and experimental results further explains the coordination mechanism.
Bacterial 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.
Peptide and protein drugs with therapeutic effects suffer from their short half-life and low stability, albeit their high efficiency and specificity. To overcome these demerits, long-acting drug delivery systems have been developed, wherein poly(lactic-co-glycolic acid) (PLGA) implants are most preferred owing to their excellent biodegradability and biocompatibility. Dozens of PLGA based products have been approved since 1986, when the first product, named Decapeptyl®, successfully marched into market. To meet the increasing demand for delivering various peptides and proteins, different kinds of technologies have been developed for lab-scale fabrication or industrial manufacture. This review aims to introduce recent advances of PLGA implants, and give a brief summary of fundamental properties of PLGA, fabrication technologies of peptides/proteins-loaded PLGA implants as well as factors influencing the drug release processes. Moreover, challenges and future perspectives are also highlighted.
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.
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.
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.
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.
The design of pseudocapacitive materials by coupling transition metal compounds with a conductive carbon matrix is important for the high performance of supercapacitors. Herein, we construct the Prussian blue analogue derived nickel-cobalt selenides coupling with nitrogen-doped carbon nanofibers (NiCoSe4-NCNFs) by carbonization and selenization of polyacrylonitrile nanofibers. The effect of selenization and element N doping on the morphological structure and surface chemistry of NiCoSe4-NCNFs are evaluated. Due to the accelerated electrolyte ion diffusion, enlarged active surface area and the modified surface chemistry by the strong interaction at NiCoSe4/NCNFs interfaces, NiCoSe4-NCNFs show excellent capacitive behaviors in 1 mol/L KOH, and the specific capacitance is 1257 F/g at 1 A/g with a rate capability of 78% and cyclic stability of 82.9%. The Gibbs free energy of adsorption OH− is calculated by density functional theory to investigate the charge storage mechanism. This work offers a new strategy to construct the transition metal selenides/carbon nanofibers hybrids for high-performance supercapacitor devices.
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.