Latest ArticlesPotassium-ion batteries (PIBs) have attracted enormous attention due to the abundance of potassium resources, low cost, fast ionic conductivity of electrolyte and relatively high operating voltage. Despite great efforts and progress, researches on PIBs are still at the initial stage, especially in the emerging field of flexible and wearable PIBs. The inevitable challenges for PIBs include low reversible capacity, unsatisfactory cycling stability and insufficient energy density, the solution to which mostly relies on designing advanced electrodes. Binder-free electrodes have emerged as promising electrode architecture for PIBs. Such electrodes avoid the use of insulating binders, which can be designed with various synergistic functional materials to address the aforementioned PIB issues and be endowed with flexibility/wearability. In this review, we mainly summarize the recent progress on binder-free electrodes for PIBs, with the focus on the methodologies, detailed strategies and functional materials for electrode construction. One strategy for binder-free electrodes is to assemble free-standing architecture with the help of carbon nanotubes (CNTs), graphitic fibers, and other carbon or mechanically robust materials, either alone or in combination. The other effective strategy is current collector substrate-assisted direct growth, including the use of carbon cloth, metal, MXenes and other conductive substrates. Additionally, challenges and research opportunities are put forward at the end as the guidance for future development of binder-free PIB devices.
The utilization of thermal energy from different sources is an important development direction for conserving energy. With the development of technology, refined and rapid utilization of thermal energy is required. Traditional thermal conductive materials cannot meet the growing needs of human beings. Therefore, people pay attention to two-dimensional graphene film materials for their thermal conductivity. This review collects current modeling group of thermal transport on graphene, including non-equilibrium Green function (NEGF) theory, molecular dynamics (MD) simulations modeling and Boltzmann transport equation method. These models can well explain several phenomena of phonon transport in graphene. Further, structural defects were discussed and expounded the effect for graphene thermal conductivity, including doping, grain boundary and defects. Deeply understanding of defects on graphene, we can better grasp the thermal conductivity of graphene from the microscopic point of view.
The design of supramolecular systems with efficient singlet oxygen generation has attracted considerable interests. Herein, an AIE-based singlet oxygen generation system with chemiluminescence properties is reported in aqueous media based on supramolecular host-guest assembly between a water-soluble pillar[5]arene (WP5) and an AIE photosensitizer (TPEDM). The formed supramolecular nanoparticles exhibit significant singlet oxygen generation ability as well as enhanced fluorescence. In addition, by introducing catalase, this H2O2-responsive supramolecular system shows increased 1O2 generation efficiency compared with the blank nanoparticles. An efficient chemiluminescence system can also be achieved by entrapping an energy donor adamantane derivative (AMPPD). Moreover, the present system can function as nanoreactors to perform the photooxidation of dopamine to form polydopamine with visible light irradiation. This work provides a new strategy for the construction of 1O2 generation system based on supramolecular nanomaterials, which has potential applications in the fields such as chemiluminescence imaging and controlled photocatalysis.
A purely organic D-π-A-π-D type emitter showing thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) was designed and synthesized by utilizing the benzophenone as an acceptor and the N-phenyl-2-napthylamine as a donor moiety. It exhibits considerable TADF character in doped PMMA film and room temperature phosphorescence with a long lifetime of 74 ms at 466 nm in solid state. The devices with the configuration of ITO/Mo2O3 (4 nm)/mCP (30 nm)/mCP: x wt% NP2BP/TmTyPB (60 nm)/LiF (1.5 nm)/Al (100 nm) were prepared by vacuum evaporation to explore their electroluminescent performance. Interestingly, the non-doped device has obtained near-white emission with a fluorescence emission peak at 475 nm and a phosphorescence emission peak at 563 nm having the CIE coordinate of (0.23, 0.32) and the maximum external quantum efficiency of 1.09%.
The σ-bond activation by main group element has received enormous attention from theoretical and experimental chemists. Here, the reaction of C–X (X=Cl, Br, Ⅰ) bonds in benzyl and allyl halides with a pincer-type phosphorus(Ⅲ) species was reported. A series of structurally robust phosphorus(Ⅴ) compounds were formed via the formal oxidative addition reactions of C–X bonds to the phosphorus(Ⅲ) center. Density functional theory calculations show that the nucleophilic addition process is more favorable than the direct oxidative addition mechanism. Isomerization of bent structures of phosphorus(Ⅲ) compound to poorly nucleophilic compounds to undergo further C–X bond activation can be rationalized by frontier molecule orbital analysis. This study not only provides a deep understanding of the reactivity of phosphorus(Ⅲ) species but also demonstrates a potential of main group elements for the small-molecule activation.
We report a 2-iodoxybenzoic acid (IBX)-mediated intarmolecular oxidative spiro-fused tandem cyclization reaction of tryptophan analogs bearing an N-arylamides side-chain to rapidly afford polycyclic spiroindolines featuring multiple stereocenters including a quaternary stereocenters under mild reaction conditions. Among them, a novelty azaphosphol idine-containing spiroindoline compound is synthesized for the first time. It may open the door to azaphos pholidine-containing spiroindoline compound of potential interest in synthetic and medicinal chemistry. A plausible mechanism is proposed.
The precise and real-time sensing of the temperature within the physiological range is of great significance in biology and medicine. Here, a Zn-based metal-organic framework (MOF) named Zn-TCOMA is synthesized with good SHG performance due to its unique structure of the ligand and 3D frameworks. By encapsulating the two-photon fluorescent dye DMASE into the pores of Zn-TCOMA, the composite Zn-TCOMA⊃DMASE is obtained and simultaneously exhibits SHG response and two-photon fluorescence. Utilizing the intensity ratio between two-photon fluorescence of DMASE and SHG signal of Zn-TCOMA, Zn-TCOMA⊃DMASE exhibits ratiometric temperature sensing property at physiological temperature region of 20~60 ℃ with high sensitivity. This MOF thermometer also shows excellent repeatability, good biocompatibility, and high temperature resolution of 0.018 ℃, opening a new avenue to develop diverse optical thermometric or thermographic applications in biotechnology or other areas.
The asymmetric transfer hydrogenation (ATH) of a wide range of ketones catalyzed by manganese complex as well as chiral PxNy-type ligand under mild conditions was investigated. Using 2-propanol as hydrogen source, various ketones could be enantioselectively hydrogenated by combining cheap, readily available [MnBr(CO)5] with chiral, 22-membered macrocyclic ligand (R, R, R', R')-CyP2N4 (L5) with 2 mol% of catalyst loading, affording highly valuable chiral alcohols with up to 95% ee.
TiO2 photocatalysts have been widely studied and applied for removing bacteria, but its antibacterial efficiency is limited to the ultraviolet (UV) range of the solar spectrum. In this work, we use the gold (Au) nanorods to enhance the visible and near-infrared (NIR) light absorption of TiO2 NBs, a typical UV light photocatalyst, thus the enhancement of its full solar spectrum (UV, visible and NIR) photocatalytic antibacterial properties is achieved. Preliminary surface plasmon resonance (SPR) enhancement photocatalytic antibacterial mechanism is suggested. On one hand, transverse and longitudinal SPR of Au NRs is beneficial for visible and NIR light utilization. On the other hand, Au NRs combined with TiO2 NBs to form the heterostructure, which can improve the photogenerated carrier separation and direct electron transfer increases the hot electron concentration while Au NRs as the electron channel can well restrain charge recombination, finally produces the high yield of radical oxygen species and exhibits a superior antibacterial efficiency. Furthermore, we design a sterilization file cabinet with Au NR/TiO2 NB heterostructures as the photocatalytic coating plates. Our study reveals that Au NR/TiO2 NB heterostructure is a potential candidate for sterilization of bacteria and archives protection.
The goal of the present study is to elucidate the intragastrointestinal fate of micellar delivery systems by monitoring fluorescently labeled different micelles and the model drug paclitaxel (PTX). Both in vitro and ex vivo leakage studies showed fast PTX release in fluids while micelles remained intact, except in fed-state simulated intestinal fluid and fasted-state pig intestinal fluid, thus referring to the intact absorption of micelles and PTX leakage in the gastrointestinal tract with d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) micelles showing higher stability than other micelles. All groups of micelles were absorbed intact in Caco-2 and Caco-2/HT29-MTX cell models and the absorption of TPGS micelles was found to be higher than other micelles. The transport of the micelles across Caco-2/Raji (1.6%–3.5%), Caco-2 (0.8%–1%), and Caco-2/HT29-MTX (0.58%–1%) cell monolayers further verified the absorption of micelles and their subsequent transport; however, more TPGS micelles transported across cell monolayers than other groups. Moreover, the histological examination also confirmed that micelles entered the enterocytes and were transported to basolateral tissues and TPGS showed the stronger ability of penetration than other groups. Thus, these results are succinctly presenting the absorption of intact micelles in GIT confirmed by imaging evidence with prior leakage of the drug, uptake by enterocytes and the transport of micelles that survive the digestion by enterocytes and mainly by microfold cells in material nature dependent way with TPGS showing better results than other groups. In conclusion, these results identify the mechanism by which the gastrointestinal tract processes micelles and point to the likely use of this approach in the design of micelles-based therapies.
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