Laser-Triggered High Graphitization of Mo2C@C: High Rate Performance and Excellent Cycling Stability as Anode of Lithium Ion Batteries.

Fast electron/ion transport and cycling stability of anode materials are key factors for achieving a high rate performance of battery materials. Herein, we successfully fabricated a carbon-coated Mo2C nanofiber (denoted as laser Mo2C@C) as the lithium ion battery anode material by laser carbonization of PAN-PMo12 (PAN = Polyacrylonitrile; PMo12 = H3PMo12O40). The highly graphitized carbon layer in laser Mo2C@C effectively protects Mo2C from agglomeration and flaking while facilitating electron transfer. As such, the laser Mo2C@C electrode displays an excellent electrochemical stability under 5 A g-1, with a capacity up to 300 mA h g-1 after 3000 cycles. Furthermore, the extended X-ray absorption fine structure results show the existence of some Mo vacancies in Mo2C@C. Density functional theory calculations further prove that such vacancies make the defective Mo2C@C composites energetically more favorable for lithium storage in comparison with the intact Mo2C.

Insight into the Structural Variation and Sodium Storage Behavior of Polyoxometalates Encapsulated within Single-Walled Carbon Nanotubes.

The host-guest interaction can remarkably alter the physiochemical properties of composite materials. It is crucial to clarify the mechanism by revealing the influence of the host on the electronic structure of the guest molecules. Herein, we study the structural variation of polyoxometalates (POMs) after being confined in single-walled carbon nanotubes (SWNT). What we found is that in addition to the reported charge transfer from SWNT to POM, an intramolecular electron transfer within a single POM cluster can be observed in the POM@SWNT composites. Moreover, the charge density on the bridged oxygen of POMs is prominently enhanced. The structural change and electron reconfiguration of POMs upon encapsulation in SWNT significantly speed up electron and ion transport, leading to the improved electrochemical performance for sodium ions storage.

Electrodeposition of Defect-Rich Ternary NiCoFe Layered Double Hydroxides: Fine Modulation of Co3+ for Highly Efficient Oxygen Evolution Reaction.

The low-cost, high-abundance and durable layered double hydroxides (LDHs) have been considered as promising electrocatalysts for oxygen evolution reaction (OER). However, the easy agglomeration of lamellar LDHs in the aqueous phase limits their practical applications. Herein, a series of ternary NiCoFe LDHs were successfully fabricated on nickel foam (NF) via a simple electrodeposition method. The as-prepared Ni(Co0.5 Fe0.5 )/NF displayed an unique nanoarray structural feature. It showed an OER overpotential of 209 mV at a current density of 10 mA cm-2 in alkaline solution, which was superior to most systems reported so far. As evidenced by the XPS and XAFS results, such excellent performance of Ni(Co0.5 Fe0.5 )/NF was attributed to the higher Co3+ /Co2+ ratio and more defects exposed, comparing with Ni(Co0.5 Fe0.5 )-bulk and Ni(Co0.5 Fe0.5 )-mono LDHs prepared by conventional coprecipitation method. Furthermore, the ratio of Co to Fe could significantly tune the Co electronic structure of Ni(Cox Fe1-x )/NF composites (x=0.25, 0.50 and 0.75) and affect the electrocatalytic activity for OER, in which Ni(Co0.5 Fe0.5 )/NF showed the lowest energy barrier for OER rate-determining step (from O* to OOH*). This work proposes a facile method to develop high-efficiency OER electrocatalysts.

Electronic Structure Reconfiguration of Self-Supported Polyoxometalate-Based Lithium-Ion Battery Anodes for Efficient Lithium Storage.

Polyoxometalate (POM)-based materials are considered as promising candidates for lithium-ion batteries (LIBs) due to their stable and well-defined molecular structure and reversible multielectron redox properties. Currently, POM-based electrode materials suffer from high interfacial resistance and low uniformity. Herein, we reported a self-supported POM-based anode material for LIBs by electrodepositing H3PMo12O40 (PMo12) and aniline on carbon cloth (CC) for the first time. The as-prepared polyaniline (PANi)-PMo12/CC composite exhibited an excellent reversible capacity of 1092 mA h g-1 for 200 cycles at 1 A g-1. Such an outstanding performance was attributed to the rapid electron transfer and Li+ diffusion stemming from the exposure of more active sites by the self-supported structure, the strong electrostatic interaction, and electronic structure reconfiguration between the active PMo12 cluster and conductive PANi polymer. This work provides insight into the electronic structure engineering of highly efficient LIB anode materials.

Double-Shelled Hollow SiO2 @N-C Nanofiber Boosts the Lithium Storage Performance of [PMo12 O40 ]3.

Polyoxometalates (POMs)-based materials, with high theoretical capacities and abundant reversible multi-electron redox properties, are considered as promising candidates in lithium-ion storage. However, the poor electronic conductivity, low specific surface area and high solubility in the electrolyte limited their practical applications. Herein, a double-shelled hollow PMo12 -SiO2 @N-C nanofiber (PMo12 -SiO2 @N-C, where PMo12 is [PMo12 O40 ]3- , N-C is nitrogen-doped carbon) was fabricated for the first time by combining coaxial electrospinning technique, thermal treatment and electrostatic adsorption. As an anode material for LIBs, the PMo12 -SiO2 @N-C delivered an excellent specific capacity of 1641 mA h g-1 after 1000 cycles under 2 A g-1 . The excellent electrochemical performance benefited from the unique double-shelled hollow structure of the material, in which the outermost N-C shell cannot only hinder the agglomeration of PMo12 , but also improve its electronic conductivity. The SiO2 inner shell can efficiently avoid the loss of active components. The hollow structure can buffer the volume expansion and accelerate Li+ diffusion during lithiation/delithiation process. Moreover, PMo12 can greatly reduce charge-resistance and facilitate electron transfer of the entire composites, as evidenced by the EIS kinetics study and lithium-ion diffusion analysis. This work paves the way for the fabrication of novel POM-based LIBs anode materials with excellent lithium storage performance.

Three-Dimensional Carbon Framework Anchored Polyoxometalate as a High-Performance Anode for Lithium-Ion Batteries.

Recently, it has become very important to develop cost-effective anode materials for the large-scale use of lithium-ion batteries (LIBs). Polyoxometalates (POMs) have been considered as one of the most promising alternatives for LIB electrodes owing to their reversible multi-electron-transfer capacity. Herein, Keggin-type [PMo12 O40 ]3- (donated as PMo12 ) clusters are anchored onto a 3D microporous carbon framework derived from ZIF-8 through electrostatic interactions. The PMo12 clusters can be immobilized steadily and uniformly on the carbon framework, which provides enhanced electrical conductivity and high stability. Compared with PMo12 itself, the as-prepared novel 3D Carbon-PMo12 composite displays a significantly improved Li-ion storage performance as an LIB anode, with excellent reversible specific capacity and rate capacity, as well as high cycling performance (discharge capacity of 985 mA h g-1 after 200 cycles), which are superior to other POM-based anode materials reported so far. The high performance of the Carbon-PMo12 composite can be attributed to the 3D conductive network with fast electron transport, high ratio of pseudocapacitive contribution, and evenly distributed PMo12 clusters with reversible 24-electron transfer capacity. This work offers a facile way to explore novel LIB anodes consisting of electroactive molecule clusters.

3D Carbon Foam Supported Edge-Rich N-Doped MoS2 Nanoflakes for Enhanced Electrocatalytic Hydrogen Evolution.

Molybdenum disulfide (MoS2 ) is one of the most promising alternatives to the Pt-based electrocatalysts for the hydrogen evolution reaction (HER). However, its performance is currently limited by insufficient active edge sites and poor electron transport. Hence, enormous efforts have been devoted to constructing more active edge sites and improving conductivity to obtain enhanced electrocatalytic performance. Herein, the 3D carbon foam (denoted as CF) supported edge-rich N-doped MoS2 nanoflakes were successfully fabricated by using the commercially available polyurethane foam (PU) as the 3D substrate and PMo12 O40 3- clusters (denoted as PMo12 ) as the Mo source through redox polymerization, followed by sulfurization. Owing to the uniform distribution of nanoscale Mo sources and 3D carbon foam substrate, the as-prepared MoS2 -CF composite possessed well-exposed active edge sites and enhanced electrical conductivity. Systematic investigation demonstrated that the MoS2 -CF composite showed high HER performance with a low overpotential of 92 mV in 1.0 m KOH and 155 mV in 0.5 m H2 SO4 at a current density of 10 mA cm-2 . This work offers a new pathway for the rational design of MoS2 -based HER electrocatalysts.

[Berberine inhibited apoptosis of human umbilical vein endothelial cells induced by Staphylocoocus aureus: an experimental research].

OBJECTIVE: To study the inhibition of berberine (BBR) against ECV-304 apoptosis induced by Staphylococcus aureus (S. aureus). METHODS: ECV-304 cells were pre-treated with 128 microg/mL BBR for 2 h and then S. aureus was added (1:100). The viability of cells was detected by MTT (3-4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The morphological changes were observed by Hoechst 33258 staining. The protection of BBR for infected cells was detected by DNA Ladder. RESULTS: ECV-304 cells' viability were not obviously affected by berberine. But S. aureus induced ECV-304 cells' viability could be significantly inhibited by pre-treatment of BBR (P < 0.05). Besides S. aureus-induced ECV-304 apoptosis could be reduced, with significantly lessened apoptotic body and unobvious DNA degradation. CONCLUSION: BBR could significantly inhibit S. aureus induced ECV-304 apoptosis.

Reduced prefrontal activation during Tower of London in first-episode schizophrenia: a multi-channel near-infrared spectroscopy study.

Cognitive impairments are considered as a core feature of schizophrenia and have been reported in associated with dysfunction of the prefrontal cortex (PFC). The Tower of London (TOL) task is a widely used neuropsychological test to assess the planning ability and the PFC function. In the present study, we examined functional changes in the PFC of 40 first-episode schizophrenia patients and 40 age- and gender-matched healthy controls by means of multi-channel Near-infrared spectroscopy (NIRS) during performance of the TOL task. NIRS is a noninvasive optical method that can measure relative changes in oxygenated ([oxy-Hb]) and deoxygenated ([deoxy-Hb]) hemoglobin in cortical tissue. Compared to the healthy controls, schizophrenia patients exhibited a significant decreased activation in the left PFC and poorer TOL performance. The results confirm the functional deficits of the PFC and impaired planning ability in first-episode schizophrenia patients and suggest that NIRS may be a useful clinical tool for evaluating PFC activation in psychiatric disorders.