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1.
ACS Appl Mater Interfaces ; 12(2): 2572-2580, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31860265

RESUMO

Recently, aluminum ion batteries (AIBs) have attracted great attention across the globe by virtue of their massive gravimetric and volumetric capacities in addition to their high abundance. Though carbon derivatives are excellent cathodes for AIBs, there is much room for further development. In this study, flexuous graphite (FG) was synthesized by a simple thermal shock treatment, and for the first time, an Al/FG battery was applied as a cathode for AIBs to reveal the real-time intercalation of AlCl4- into FG with high flexibility by using in-situ scanning electron microscope (SEM) measurements exclusively. Similarly, in-situ X-ray diffraction (XRD) and in-situ Raman techniques have been used to understand the anomalous electrochemical behavior of FG. It was found that FG adopts a unique integrated intercalation-adsorption mechanism where it follows an intercalation mechanism potential above 1.5 V and an adsorption mechanism potential below 1.5 V. This unique integrated intercalation-adsorption mechanism allows FG to exhibit superior properties, like high capacity (≥140 mAh/g), remarkable long-term stability (over 8000 cycles), excellent rate retention (93 mAh/g at 7.5 A/g), and extremely rapid charging and slow discharging.

2.
Chemistry ; 22(30): 10620-6, 2016 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-27346677

RESUMO

Herein, mesoporous sodium vanadium phosphate nanoparticles with highly sp(2) -coordinated carbon coatings (meso-Na3 V2 (PO4 )3 /C) were successfully synthesized as efficient cathode material for rechargeable sodium-ion batteries by using ascorbic acid as both the reductant and carbon source, followed by calcination at 750 °C in an argon atmosphere. Their crystalline structure, morphology, surface area, chemical composition, carbon nature and amount were systematically explored. Following electrochemical measurements, the resultant meso-Na3 V2 (PO4 )3 /C not only delivered good reversible capacity (98 mAh g(-1) at 0.1 A g(-1) ) and superior rate capability (63 mAh g(-1) at 1 A g(-1) ) but also exhibited comparable cycling performance (capacity retention: ≈74 % at 450 cycles at 0.4 A g(-1) ). Moreover, the symmetrical sodium-ion full cell with excellent reversibility and cycling stability was also achieved (capacity retention: 92.2 % at 0.1 A g(-1) with 99.5 % coulombic efficiency after 100 cycles). These attributes are ascribed to the distinctive mesostructure for facile sodium-ion insertion/extraction and their continuous sp(2) -coordinated carbon coatings, which facilitate electronic conduction.

3.
Chemistry ; 21(44): 15686-91, 2015 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-26350587

RESUMO

Herein, potential-tunable Na2 Ni1-x Cux Fe(CN)6 nanoparticles with three-dimensional frameworks and large interstitial spaces were synthesized as alternative cathode materials for aqueous sodium-ion batteries by controlling the molar ratio of Ni(II) to Cu(II) at ambient temperature. The influence of the value of x on the crystalline structure, lattice parameters, electrochemical properties, and charge transfer of the resultant compound was explored by using powder X-ray diffractometry, density functional theory, cyclic voltammetry, galvanostatic charge-discharge techniques, and Bader charge analysis. Of the various formulations investigated, that with x=0.25 delivered the highest reversible capacity, superior rate capability, and outstanding cycling performance. These attributes are ascribed to its unique face-centered cubic structure for facile sodium-ion insertion/extraction and the strong interactions between Cu and N atoms, which promote structural stability.

4.
ACS Nano ; 8(1): 443-8, 2014 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-24359599

RESUMO

Graphene is expected to enable superior corrosion protection due to its impermeability and chemical inertness. Previous reports, however, demonstrate limited corrosion inhibition and even corrosion enhancement of graphene on metal surfaces. To enable the reliable and complete passivation, the origin of the low inhibition efficiency of graphene was investigated. Combining electrochemical and morphological characterization techniques, nanometer-sized structural defects in chemical vapor deposition grown graphene were found to be the cause for the limited passivation effect. Extremely fast mass transport on the order of meters per second both across and parallel to graphene layers results in an inhibition efficiency of only ∼50% for Cu covered with up to three graphene layers. Through selective passivation of the defects by atomic layer deposition (ALD) an enhanced corrosion protection of more than 99% was achieved, which compares favorably with commercial corrosion protection methods.

5.
J Nanosci Nanotechnol ; 10(8): 5364-8, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21125899

RESUMO

In this study, poly(acrylic)/SiO2/EuL3 x 2H2O hybrid thin films were prepared from various acrylic monomers (MMA and EDMA/TMPTA), lanthanide metal complexes (EuL3 x 2H2O, L = pyridine carboxylic acid), and monodispersed colloidal silica with a coupling agent, 3-(trimethoxysilyl)propyl methacrylate (MSMA). It is a combination of the sol-gel reaction, thermal polymerization, and spin coating. The silica content in the hybrid thin films is fixed at 20 wt%, and the EuL3 x 2H2O content is varied from 0.01 g to 0.07 g. FTIR and EA analysis confirms the chemical structure of the prepared EuL3 x 2H2O and poly(acrylic)/SiO2/EuL3 x 2H2O hybrid thin films. UV-Vis spectra and n&k analysis shows that the hybrid thin film has good transparency in visible light. The refractive index of hybrid thin films can be effectively controlled through the EuL3 x 2H2O content. The PL spectra shows that the strongest emission peak occurs at 615 nm and the emission intensity increases to the peak maximum at an EuL3 x 2H2O content of 0.05 g. Both TGA and PL analysis show that the prepared hybrid thin films from the crosslinked acrylic polymer moiety have much better film uniformity, thermal stability, and fluorescence properties. The TEM diagram shows that the MSMA/SiO2/EuL3 x 2H2O particles with a size 15-20 nm are well dispersed in the reaction solution. The SEM diagram shows that the particle distribution in the prepared hybrid thin films is uniform and no phase separation is observed. Finally, AFM analysis indicates that the prepared hybrid thin films have an excellent surface planarity.

6.
Biomacromolecules ; 11(4): 1101-10, 2010 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-20201492

RESUMO

This work describes a novel tunable bioadhesive hydrogel of thermoresponsive N-isopropylacrylamide (NIPAAm) containing zwitterionic sulfobetaine methacrylate (SBMA). This novel hydrogel highly regulates general bioadhesive foulants through the adsorption of plasma proteins, the adhesion of human platelets and cells, and the attachment of bacteria. In this investigation, nonionic hydrogels of polyNIPAAm, zwitterionic hydrogels of polySBMA, and three copolymeric hydrogels of NIPAAm and SBMA (poly(NIPAAm-co-SBMA)) were prepared. The copolymeric hydrogels exhibited controllable temperature-dependent swelling behaviors and showed stimuli-responsive phase characteristics in the presence of salts. The interactions of these hydrogels with biomolecules and microorganisms were demonstrated by protein adsorption, cell adhesion, and bacterial attachment, which allowed us to evaluate their bioadhesive properties. An enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies was used to measure different plasma protein adsorptions on the prepared hydrogel surfaces. At a physiological temperature, the high content of the nonionic polyNIPAAm in poly(NIPAAm-co-SBMA) hydrogel exhibits a high protein adsorption due to the interfacial exposure of polyNIPAAm-rich hydrophobic domains. A relatively high content of polySBMA in poly(NIPAAm-co-SBMA) hydrogel exhibits reduced amounts of protein adsorption due to the interfacial hydration of polySBMA-rich hydrophilic segments. The attachment of platelets and the spreading of cells were only observed on polyNIPAAm-rich hydrogel surfaces. Interestingly, the incorporation of zwitterionic SBMA units into the polyNIPAAm gels was found to accelerate the hydration of the cell-cultured surfaces and resulted in more rapid cell detachment. Such copolymer gel surface was shown to be potentially useful for triggered cell detachment. In addition, the interactions of hydrogels with bacteria were also evaluated. The polySBMA-rich hydrogels exhibited evident antimicrobial properties when they were incubated with Gram-positive bacteria ( S. epidermidis ) and Gram-negative bacteria ( E. coli ). This work shows that the bioadhesive properties of poly(NIPAAm-co-SBMA) hydrogels can be effectively controlled via regulated nonionic and zwitterionic molar mass ratios. The tunable-bioadhesive behavior of temperature-sensitive poly(NIPAAm-co-SBMA) makes this biocompatible hydrogel appropriate for biomedical applications.


Assuntos
Acrilamidas/química , Betaína/análogos & derivados , Materiais Biocompatíveis/química , Adesão Celular , Hidrogéis/química , Polímeros/química , Betaína/química , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/metabolismo , Plaquetas/metabolismo , Proteínas Sanguíneas/metabolismo , Células Cultivadas , Escherichia coli/metabolismo , Fibroblastos/metabolismo , Humanos , Polímeros/síntese química , Polímeros/metabolismo , Staphylococcus epidermidis/metabolismo , Propriedades de Superfície , Temperatura Ambiente
7.
J Nanosci Nanotechnol ; 8(3): 1537-44, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18468187

RESUMO

Nanoporous poly(methyl silsesquioxane) (PMSSQ) film was prepared through the templating of an amphiphilic block copolymer, poly(styrene-4-vinyl pyridine) (PS-b-P4VP). The experimental and theoretical studies suggest that the intermolecular hydrogen bonding is existed between the PMSSQ precursor and PS-b-P4VP. The miscible hybrid and the narrow thermal decomposition of the PS-b-P4VP lead to nanopores in the prepared films from the results of TGA, AFM, and TEM. The effects of the loading ratio on the morphology and properties of the prepared nanoporous PMSSQ films were investigated. The TEM and AFM studies show that the uniform pore morphology with pore size 10-15 nm can be prepared from a modest porogen loading level for the optimum intermolecular hydrogen bonding. The refractive index and dielectric constant of the prepared nanoporous films decreases with an increase in PS-b-P4VP loading. On the other hand, the porosity increases with an increasing PS-b-P4VP loading. This study demonstrates a methodology to control pore morphology and properties of the nanoporous PMSSQ films through the templating of PS-b-P4VP.

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