Enhancing the Cycle Performance of Lithium-Sulfur Batteries by Coating the Separator with a Cation-Selective Polymer Layer.

Lithium-sulfur batteries are believed to possess the feasibility to power electric vehicles in the future ascribed to the competitive energy density. However, soluble polysulfides continuously shuttle between the sulfur electrode and lithium anode across the separator, which dramatically impairs the battery's capacity. Herein, the surface of a polypropylene separator (PP film) is successfully modified with a delicately designed cation-selective polymer layer to suppress the transport of polysulfides. In principle, since bis-sulfonimide anions groups on the backbone of the polymer are immobilized, only cations can pass through the polymer layer. Furthermore, plenty of ethoxy chains in the polymer can facilitate lithium-ion mobility. Consequently, in addition to obstructing the movement of negatively charged polysulfides by the electrostatic repulsive force of fixed anions, the coated multi-functional layer on the PP film also guarantees the smooth conduction of lithium ions. The investigations demonstrate that the battery with the pristine PP film only delivers 228.5 mAh g-1 after 300 cycles at 2 C with a high capacity fading rate of 60.9 %. By contrast, the polymer-coated sample can release 409.4 mAh g-1 under the identical test condition and the capacity fading rate sharply declines to 43.2 %, illustrating superior cycle performance.

Fabrication and Evaluation of Graphene Oxide/Hydroxypropyl Cellulose/Chitosan Hybrid Aerogel for 5-Fluorouracil Release.

The incorporation of graphene oxide (GO) into a polymeric drug carrier can not only enhance the loading efficiency but also reduce the initial burst and consequently improve the controllability of drug release. Firstly, 5-fluorouracil (5-Fu)-loaded hydroxypropyl cellulose/chitosan (HPC/CS@5-Fu) and GO/HPC/CS@5-Fu aerogels were successfully fabricated through chemical cross-linking with glutaraldehyde. Then, the obtained aerogels were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FITR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry (TG), and the effect of HPC and GO content on the drug loading (DL) and encapsulation efficiency (EE) for the two aerogels were investigated, respectively. Finally, the drug release behavior of the GO/HPC/CS@5-Fu aerogels with different GO content was evaluated at two different pH values, and four kinds of kinetic models were used to evaluate the release behavior.

New Insight into a Fenton-like Reaction Mechanism over Sulfidated ß-FeOOH: Key Role of Sulfidation in Efficient Iron(III) Reduction and Sulfate Radical Generation.

Sulfidation can greatly improve the efficiency of utilization of reducing equivalents for contaminant removal; however, whether this method benefits Fenton-like reactions or not and the possible mechanism are not well understood. In this study, we revealed that surface sulfidation can greatly promote the heterogeneous Fenton activity of ß-FeOOH (Fe3S4@ß-FeOOH) by 40 times, in which not only the •OH formation was enhanced but also SO4•- as a new oxidation species was generated. Moreover, their contribution to metronidazole (MTZ) degradation was 52.5 and 37.1%, respectively. In comparison, almost no HO2•/O2•- was detected in the Fe3S4@ß-FeOOH/H2O2 system. These results were different from some previously reported Fenton counterparts. Based on the characterization and probe experiments, sulfur species, including S2-, S0, and Sn2-, as an electron donor and electron shuttle were responsible for efficient conversion of Fe(III) into Fe(II) other than via the Haber-Weiss mechanism, leading to excellent •OH generation via a Fenton-like mechanism. Most importantly, HSO5- can be generated from SO32- oxidized by •OH, and its scission into SO4•- was not dependent on the extra electric potential or Fe-O2-S(IV) intermediate. These findings provided new insight for utilizing sulfidation to improve the activity of iron-based Fenton catalysts.

Smartphone as a simple device for visual and on-site detection of fluoride in groundwater.

Developing a portable device for visual and on-site detection of fluoride in groundwater is highly anticipated. In this paper, 2-(tert-butyl-diphenylsilanyloxy)-5-nitro-1H-benzoimidazole (1) has been rationally designed via a silanization reaction for self-calibration detection of fluoride, and the detection limit was calculated as 0.11 µM. The contact of 1 with fluoride would induce the cleavage of Si-O bond and trigger the emergence of excited state intramolecular proton transfer (ESIPT) process, and then the enol-like emission at 437 nm decreased accompanying with the increase of keto-like tautomerism emission at 550 nm. More importantly, considering the demand of field detection for fluoride in groundwater and combining the function of smartphone to obtain the chroma of photos. The chroma value of the fluorescence color changes from blue to yellow could be conveniently determined through a color recognizer application installed in smartphone. The device can accurately reflect the concentration of fluoride by analyzing the chroma value. The test in actual water samples confirmed that the simple device based on smartphone could be used efficiently for visual, on-site and accurate detection of fluoride in groundwater.

More reactive oxygen species generation facilitated by highly dispersed bimodal gold nanoparticle on the surface of Bi2WO6 for enhanced photocatalytic degradation of ofloxacin in water.

An essential strategy to eliminate emerging contamination in water is to initiate more reactive oxygen species (ROS) in the catalytic systems. 0.14 wt.% Au loaded Bi2WO6 (Bi2WO6/Au-400 °C) was fabricated after 400 °C annealing with the assistance of glutathione for Au atom anchoring and stabilization on Bi2WO6 surface. Bimodal Au size distribution of highly dispersed small size clusters (0.5 ± 0.1 nm) and large size nanoparticles (6.3 ± 1.0 nm) simultaneously existed on Bi2WO6 nanosheets in Bi2WO6/Au-400 °C, which were verified through high resolution transmission electron microscopy (HR-TEM). 95% of ofloxacin (OFX) was degraded over Bi2WO6/Au-400 °C in 180 min under visible light irradiation with a reaction constant of 24.5 × 10-3 min-1, which showed 3.0 and 2.5-fold enhancement compared with bare Bi2WO6 and unimodal Bi2WO6/Au-500 °C (annealed at 500 °C, Au NPs (8.6 ± 1.0 nm)), respectively. The enhanced catalytic activity originated from the additional ROS production that initiated by photo-induced electron transported from small Au clusters to large Au NPs through the conduction band of Bi2WO6. Moreover, it still maintained a good stability after five cycling performance and the total cost of 10 g Bi2WO6/Au-400 °C was estimated to be 6.78 $. Lower-content of bimodal Au NPs decorated Bi2WO6 catalyst possesses high efficiency to degrade pollutant and lower cost, which provides a promising alternative in practical environmental remediation by photocatalysis.

Fluorescent Copolymers for Bacterial Bioimaging and Viability Detection.

Novel fluorescent labels with high photostability and high biocompatibility are required for microbiological imaging and detection. Here, we present a green fluorescent polymer chain (GFPC), designed to be nontoxic and water-soluble, for multicolor bioimaging and real-time bacterial viability determination. The copolymer is synthesized using a straightforward one-pot reversible addition-fragmentation chain-transfer (RAFT) polymerization technique. We show that GFPC does not influence bacterial growth and is stable for several hours in a complex growth medium and in the presence of bacteria. GFPC allows the labeling of the bacterial cytoplasm for multicolor bacterial bioimaging applications. It can be used in combination with propidium iodide (PI) to develop a rapid and reliable protocol to distinguish and quantify, in real time, by flow cytometry, live and dead bacteria.

Efficient fenton-like degradation of ofloxacin over bimetallic Fe-Cu@Sepiolite composite.

An effective method for increasing the utilization efficiency of active components in heterogeneous Fenton-like catalysts was provided. 1.5 at.% Fe-Cu bimetal on 1D sepiolite (Sep) (D-FeCu@Sep) with high dispersion and reduced chemical valence was prepared via complexation-carbonization process of glutathione. 93% of ofloxacin (OFX, a typical antibiotic of emerging concern) was degraded over D-FeCu@Sep without any extra energy input at the optimum conditions (100 mL 10 mg/L OFX, pH 5.0, 3.0 g/L catalyst and 0.03 M H2O2), which was enhanced by 2.3, 3.0 and 1.7 times compared with aggregated Fe-Cu on Sep (A-FeCu@Sep), monometallic Fe on Sep (D-Fe@Sep) and Fe-Cu on blocky Celite (D-FeCu@Celite), respectively. Moreover, it exhibited an excellent performance at a wide working pH range from acidic to neutral conditions (pH 3.2-7.2) with a satisfied stability. Based on the characterizations of X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H2-TPR) and electrochemical impedance spectroscopy (EIS), the proposed complexation-carbonization process of glutathione played an important role in the good Fenton performance of D-FeCu@Sep. The complexation of Fe and Cu ion by glutathione favors the high dispersion of Fe-Cu active component, afterward the reduced chemical valence results from carbonization process of glutathione. Moreover, the 1D nanofibrous structure of D-FeCu@Sep could greatly increase the surface electron transfer efficiency compared with D-FeCu@Celite. This study provides a method alternative to the heterogeneous Fenton chemistry by increasing the utilization efficiency of active components.

Significant enhancement of photo-Fenton degradation of ofloxacin over Fe-Dis@Sep due to highly dispersed FeC6 with electron deficiency.

An efficient strategy for enhancing iron efficiency in heterogeneous Fenton reaction via the pyrolysis of ferrocene chemically modified sepiolite (Sep) was proposed in this study. Highly dispersed FeC6 on sepiolite (Fe-Dis@Sep) was synthesized as an efficient photo-Fenton catalyst for the visible light degradation of ofloxacin (OFX). It exhibits an excellent Fenton activity and stability towards OFX degradation. The pseudo-first order reaction rate constant of Fe-Dis@Sep was 5.1-fold higher than that of the supported catalyst with aggregated iron oxides prepared by traditional impregnation method (Fe-Agg@Sep). Based on TEM images and density functional theory (DFT) calculation, the enhanced Fenton activity of Fe-Dis@Sep was attributed to the unique incorporation of FeC6 on Sep via Si-O-C-Fe bond which not only favor the high dispersion of FeC6 with an electron deficiency but also promote Fe(III) to Fe(II) cycle via the formation of surface Fe-H2O2 complex. OH and O2- were identified as active species for OFX degradation in Fe-Dis@Sep-H2O2-Vis system. 98.7% of F and 97.0% of N in OFX was converted into F- and NO3- with a TOC removal efficiency of 89.35%. The possible degradation pathway of OFX was also proposed according to HPLC-MS results. Finally, the Fenton reaction mechanism over Fe-Dis@Sep was discussed.

Convenient One-Pot Synthesis of 1,2,3,4-Thiatriazoles Towards a Novel Electron Acceptor for Highly-Efficient Thermally-Activated Delayed-Fluorescence Emitters.

A novel and unexpected convenient one-pot synthesis of 1,2,3,4-thiatriazoles has been discovered while investigating the classical tetrazine "Pinner synthesis". The synthetic route starts from commercially-available nitrile derivatives and gives good to high yields (51-80 %) with no need to isolate any thioacylating agents. The crucial impact of the solvent on the outcome of the modified "Pinner synthesis" is moreover examined and discussed. Using this new synthetic route, a novel donor-acceptor thiatriazole derivative has been prepared, which exhibits prominent thermally-activated delayed fluorescence (TADF) in both solution and film. The photoluminescence quantum yield (PLQY) in methylcyclohexane (MCH) and Zeonex (a cyclo olefin polymer) in oxygen-free conditions were determined to be 76 and 99 %, respectively. This work provides an efficient and practical synthetic approach to functionalized 1,2,3,4-thiatriazole derivatives, and will noticeably facilitate the application of 1,2,3,4-thiatriazole as an electron acceptor in organic electronics.

Novel erythrocyte-like graphene microspheres with high quality and mass production capability via electrospray assisted self-assembly.

We report for the first time a novel erythrocyte-like graphene microsphere (ELGMs) which can be produced with high quality and mass production capability via electrospray assisted self-assembly. Through simple electrospray treatment of GO suspension into coagulation bath followed by chemical reduction, large quantity of ELGMs with uniform morphology and size can be obtained with production rate of around 2.4 mg/h. Compared with other 3D structures, the ELGMs have a very interesting structural characteristic of perfect exterior doughnut shape and interior porous network. Accordingly, the as-prepared porous ELGMs exhibit excellent capability for fast and recyclable removal of oil and toxic organic solvents from water, reaching up to 216 times of its weight in absorption efficiency, which is tens of times higher than that of conventional sorbent materials. It is strongly believed that the novel hierarchical graphene structures and synergy among different techniques will lead to more future advances in graphene applications.