Transmission electron microscopy analysis of some transition metal compounds for energy storage and conversion

This work was preliminarily supported by the National Key Research Program of China (2016YFA0202604), the Natural Science Foundation of China (21476271), NSFC-RGC (21461162003) and Natural Science Foundation (2014KTSCX004 and 2014A030308012) of Guangdong Province, China.Recently, transition metal compounds (TMCs) have been employed as high-performance electrode materials for lithium ion batteries (LIBs) and supercapacitors (SCs) owing to their high specific capacities, high electrical conductivity, and high chemical and thermal stability. While the characterization of electrochemical properties of TMC anodes is well developed, new challenges arise in understanding the structure-property relationships. Transmission electron microscopy (TEM) is a powerful tool for studying microstructural characteristics. With TEM and related techniques, fundamental understanding of how the microstructures affect the properties of the TMC nanostructured anodes can be improved. In this article, the application of TEM in characterization of some typical TMC anode materials optimized through structural engineering, elemental doping, surface modification, defect-control engineering, morphological control, etc. is reviewed. Emphasis is given on analyzing the microstructures, including surface structures, various defects, local chemical compositions and valence states of transition metals, aimed at illustrating a structure-property relationship. The contribution and future development of the TEM techniques to elucidation of the electrochemical properties of the TMC anodes are highlighted.PostprintPeer reviewe

Dual-mobility cup total hip arthroplasty improves the quality of life compared to internal fixation in femoral neck fractures patients with severe neuromuscular disease in the lower extremity after stroke: a retrospective study

BackgroundThis study aimed to demonstrate that dual-mobility cup total hip arthroplasty (DMC-THA) can significantly improve the quality of life (QOL) of elderly femoral neck fracture patients with severe neuromuscular disease in unilateral lower extremities due to stroke hemiplegia compared to internal fixation (IF).MethodsFifty-eight cases of severe neuromuscular disease in the unilateral lower extremities with muscle strength < grade 3/5 due to stroke were retrospectively examined From January 2015 to December 2020. Then, patients were divided into DMC and IF groups. The QOL was examined using the EQ-5D and SF-36 outcome measures. The physical and mental statuses were assessed using the Barthel Index (BI) and e Fall Efficacy Scale-International (FES-I), respectively.ResultsPatients in the DMC group had higher BI scores than those in the IF group at different time point. Regarding mental status, the FES-I mean score was 42.1 ± 5.3 in the DMC group and 47.3 ± 5.6 in the IF group (p = 0.002). For the QOL, the mean SF-36 score was 46.1 ± 18.3 for the health component and 59.5 ± 15.0 for the mental component in the DMC group compared to 35.3 ± 16.2 (p = 0.035), and 46.6 ± 17.4 (p = 0.006) compared to the IF group. The mean EQ-5D-5L values were 0.733 ± 0.190 and 0.303 ± 0.227 in the DMC and IF groups (p = 0.035), respectively.ConclusionDMC-THA significantly improved postoperative QOL compared to IF in elderly patients with femoral neck fractures and severe neuromuscular dysfunction in the lower extremity after stroke. The improved outcomes were related to the enhanced early, rudimentary motor function of patients

Layer-by-Layer CdS-Modified TiO

A layer-by-layer assemble method was used to fabricate CdS quantum dots (QDs) sensitized electrodes. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM) have been utilized to characterize the samples. The absorption spectra and photovoltaic measurement confirmed that much more effective deposition of QDs in TiO2 matrix and much better power conversion performance were achieved for these multilayer electrodes compared with the ones fabricated by traditional single-layer assembly method

A High-Rate Two-Dimensional Polyarylimide Covalent Organic Framework Anode for Aqueous Zn-Ion Energy Storage Devices

Rechargeable aqueous Zn-ion energy storage devices are promising candidates for next-generation energy storage technologies. However, the lack of highly reversible Zn2+-storage anode materials with low potential windows remains a primary concern. Here, we report a two-dimensional polyarylimide covalent organic framework (PI-COF) anode with high-kinetics Zn2+-storage capability. The well-organized pore channels of PI-COF allow the high accessibility of the build-in redox-active carbonyl groups and efficient ion diffusion with a low energy barrier. The constructed PI-COF anode exhibits a specific capacity (332 C g–1 or 92 mAh g–1 at 0.7 A g–1), a high rate capability (79.8% at 7 A g–1), and a long cycle life (85% over 4000 cycles). In situ Raman investigation and first-principle calculations clarify the two-step Zn2+-storage mechanism, in which imide carbonyl groups reversibly form negatively charged enolates. Dendrite-free full Zn-ion devices are fabricated by coupling PI-COF anodes with MnO2 cathodes, delivering excellent energy densities (23.9 ∼ 66.5 Wh kg–1) and supercapacitor-level power densities (133 ∼ 4782 W kg–1). This study demonstrates the feasibility of covalent organic framework as Zn2+-storage anodes and shows a promising prospect for constructing reliable aqueous energy storage devices

Interlayer gap widened α-phase molybdenum trioxide as high-rate anodes for dual-ion-intercalation energy storage devices

Employing high-rate ion-intercalation electrodes represents a feasible way to mitigate the inherent trade-off between energy density and power density for electrochemical energy storage devices, but efficient approaches to boost the charge-storage kinetics of electrodes are still needed. Here, we demonstrate a water-incorporation strategy to expand the interlayer gap of α- MoO3, in which water molecules take the place of lattice oxygen of α-MoO3. Accordingly, the modified α-MoO3 electrode exhibits theoretical-value-close specific capacity (963 C g−1 at 0.1mV s−1), greatly improved rate capability (from 4.4% to 40.2% at 100 mVs−1) and boosted cycling stability (from 21 to 71% over 600 cycles). A fast-kinetics dual-ion-intercalation energy storage device is further assembled by combining the modified α-MoO3 anode with an anion-intercalation graphite cathode, operating well over a wide discharge rate range. Our study sheds light on a promising design strategy of layered materials for high-kinetics charge storage

Synthesis of Indium Nanowires by Galvanic Displacement and Their Optical Properties

<p>Abstract</p> <p>Single crystalline indium nanowires were prepared on Zn substrate which had been treated in concentrated sulphuric acid by galvanic displacement in the 0.002 mol L^&#8722;1In₂(SO₄)₃-0.002 mol L^&#8722;1SeO₂-0.02 mol L^&#8722;1SDS-0.01 mol L^&#8722;1citric acid aqueous solution. The typical diameter of indium nanowires is 30 nm and most of the nanowires are over 30 &#956;m in length. XRD, HRTEM, SAED and structural simulation clearly demonstrate that indium nanowires are single-crystalline with the tetragonal structure, the growth direction of the nanowires is along [100] facet. The UV-Vis absorption spectra showed that indium nanowires display typical transverse resonance of SPR properties. The surfactant (SDS) and the pretreatment of Zn substrate play an important role in the growth process. The mechanism of indium nanowires growth is the synergic effect of treated Zn substrate (hard template) and SDS (soft template).</p

Controlling of structural ordering and rigidity of β-SiAlON:Eu through chemical cosubstitution to approach narrow-band-emission for light-emitting diodes application

The authors are grateful for the financial support of the Ministry of Science and Technology of Taiwan (Contract Nos. MOST 104- 2113-M-002-012-MY3, MOST 104-2119-M-002-027-MY3 and 104-2923-M-002-007-MY3) and Australia Research Council (ARC, FT160100251). The contribution of A. L. was supported by the grant “Preludium” UMO-2014/13/N/ST3/03781 from the National Science Center. The contribution of S. M. was supported by the grant “Iuventus Plus” 0271/IP3/2015/73 from the Ministry of Science and Higher Education. M. G. was supported by Polish National Center for Research and Development with grants no PBS3/A5/48/2015 and PL-TWII/8/2015.Narrow-band green-emitting phosphor β-SiAlON:Eu has been widely used in advanced wide-gamut backlighting de- vices. However, the origins for unusual sharp lines in photoluminescence emission at room temperature and tunable narrow-band- emission tailored by reducing Al-O in β-SiAlON:Eu are still unclear. Here, the presence of sharp-line fine structure in the emission spectra of β-SiAlON:Eu is mainly due to purely electronic transitions (zero phonon lines) and their vibronic repetitions resulted from the multi-microenvironment around Eu2+ ions that has been revealed by relative emission intensity of sharp line depends on excitation wavelength and monotonously increasing decay time. The specific features of the Eu2+ occupying interstitial sites indicate that the effect of crystal field strength can be neglected. Therefore the enhanced rigidity and higher ordering structure of β-SiAlON:Eu with decreasing the substitution of Si–N by Al–O become the main factors in decreasing electron–lattice coupling and reducing inhomo- geneous broadening, favouring the blue-shift and narrow of the emission band, the enhanced thermal stability, as well as the charge state of Eu2+. Our results provide new insights for explaining the reason for narrow-band-emission in β-SiAlON:Eu, which will deliver an impetus for the exploration of phosphors with narrow band and ordering structure.PostprintPeer reviewe

Formation Mechanism of CaTiO₃ Hollow Crystals with Different Microstructures

The crystal growth of CaTiO3 hollow crystals with different microstructures has been investigated. In a water-free poly(ethylene glycol) 200 (PEG-200) solution, CaTiO3 nanocubes formed first. The nanocubes underwent an oriented self-assembly into spherical particles, enhanced by the surface-adsorbed polymer molecules. Since the growth of nanocubes and their aggregation took place simultaneously, the nanocubes in the outer shells were larger than those in the cores. Disappearance of the small nanocubes in the cores of the spheres during an Ostwald ripening process led to spherical hollow crystals. Addition of a small amount of water (1.25 vol %) in the polymer solution enhanced surface recrystallization of the aggregated spheres, forming a cubic morphology. The orthorhombic distortion of the perovskite CaTiO3 structure did not have a significant effect on the nanocube aggregation, resulting in a domain structure in the shells. Single-crystalline hollow cubes were produced with a slightly higher water content, e.g., 5 vol %. This process of (1) aggregation of nanocubes and (2) surface crystallization followed by (3) surface-to-core extension of recrystallization gives a good example of the reversed crystal growth route in ceramic materials. The proposed formation mechanism of the hollow CaTiO3 crystals would enable us to control the microstructures of these materials and to explain the formation of many other hollow crystals.</p

Planktonic ciliates in different water masses in open waters near Prydz Bay (East Antarctica) during austral summer, with an emphasis on tintinnid assemblages

International audiencePlanktonic ciliates are important microzooplankton in pelagic ecosystems. Previous studies in Antarctic waters have only investigated ciliate assemblages in different habitats without considering water masses. In this article, we report the characteristics of ciliate assemblages in different water masses in open waters near Prydz Bay (East Antarctica) during austral summer. Three water masses were identified according to temperature and salinity: Summer Surface Water (SSW), Winter Water (WW), and Circumpolar Deep Water (CDW). SSW was further divided into SSW Chl a 3 mg m −3) and SSW Chl a WW > CDW. SSW Chl a > 3 had a higher proportion (38.2%) of tintinnids to the total ciliate abundance and larger aloricate ciliates (ciliates in the 10-20 µm size class were 30%) of Southern Ocean endemic tintinnid species in total tintinnid abundance than in other water masses. Each water mass had the following indigenous tintinnid species: SSW, Salpingella sp., Codonellopsis gaussi; WW, Salpingella costata, S. faurei, Cymatocylis affinis/convallaria forma drygalskii, and C. vanhoeffeni. Laackman-niella naviculaefera and C. affinis/convallaria forma cristallina were present at high abundance in both WW and SSW Chl a > 3. Upwelling caused discontinuity of the ciliate distribution. Our results will help predict the spatial and temporal variations of ciliate assemblages and other plankton according to the dynamics of water masses in Antarctic waters