Concentration-gradient layered LiNi0.8Co0.20.7Ni0.2Mn0.80.3O2 oxide with Ni-rich in the core and Mn-rich in the surface region has been synthesized through a condition-controlled tank reactor ...reaction. While the Ni-rich core facilitates high capacity, the Mn-rich surface enables good cyclability and thermal stability. The concentration-gradient sample exhibits a higher capacity of 204mAhg−1 at C/5 rate with superior cyclability and thermal stability compared to the constant-concentration LiNi0.62Co0.14Mn0.24O2 sample, which has the same net Ni, Co, and Mn contents as those present in the concentration-gradient sample. The concentration-gradient sample was also coated with a thin layer of Al2O3 on the surface to stabilize the electrode/electrolyte interface and thereby further improve the electrochemical performance. Both the structural (gradient structure) and surface (Al2O3 coating) modifications help suppress side reactions between electrode and electrolyte and reduce the decline in voltage during cycling. The Al2O3-coated concentration-gradient sample exhibits improved long-term cyclability, rate capability, and thermal stability compared to the pristine uncoated sample.
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•Concentration-gradient Ni-rich layered oxides have been prepared for lithium-ion batteries.•The material comprises a Ni-rich core and a Mn-rich surface.•Concentration-gradient sample shows superior electrochemical performance.•A thin layer of Al2O3 is applied on concentration-gradient sample for further protection.•Al2O3 coated sample offers improved cyclability, rate capability, and thermal stability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Nonfullerene acceptors (MQ3, MQ5, MQ6) are synthesized using asymmetric and symmetric ladder‐type heteroheptacene cores with selenophene heterocycles. Although MQ3 and MQ5 are constructed with the ...same number of selenophene heterocycles, the heteroheptacene core of MQ5 is end‐capped with selenophene rings while that of MQ3 is flanked with thiophene rings. With the enhanced noncovalent interaction of O⋅⋅⋅Se compared to that of O⋅⋅⋅S, MQ5 shows a bathochromically shifted absorption band and greatly improved carrier transport, leading to a higher power conversion efficiency (PCE) of 15.64 % compared to MQ3, which shows a PCE of 13.51 %. Based on the asymmetric heteroheptacene core, MQ6 shows an improved carrier transport induced by the reduced π–π stacking distance, related with the increased dipole moment in comparison with the nonfullerene acceptors based on symmetric cores. MQ6 exhibits a PCE of 16.39 % with a VOC of 0.88 V, a FF of 75.66 %, and a JSC of 24.62 mA cm−2.
Selenophene end‐capped asymmetric heteroheptacene core is used to construct an efficient nonfullerene acceptor (MQ6) which shows increased carrier transport due to the enhanced O⋅⋅⋅Se intramolecular noncovalent interaction as well as the increased dipole moment. MQ6 exhibits an outstanding efficiency of 16.39 % when blended with a wide band gap copolymer.
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The unique TiO2–C/MnO2 core–double-shell nanowires are synthesized for the first time using as anode materials for lithium ion batteries (LIBs). They combine both advantages from TiO2 such as ...excellent cycle stability and MnO2 with high capacity (1230 mA h g–1). The additional C interlayer intends to improve the electrical conductivity. The self-supported nanowire arrays grown directly on current-collecting substrates greatly simplify the fabrication processing of electrodes without applying binder and conductive additives. Each nanowire is anchored to the current collector, leading to fast charge transfer. The unique one-dimensional core–double-shell nanowires exhibit enhanced electrochemical performance with a higher discharge/charge capacity, superior rate capability, and longer cycling lifetime.
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Na2Ti2O5 (NTO) nanowire arrays coated with VS2 nanosheets (NTO–VS2) have been directly prepared on a current collector as a 3D anode for Na-ion batteries. Compared to graphite, the larger interlayer ...spacing of two dimensional VS2 can offer facile intercalation of lithium and/or sodium ions. Aside from its natural metallic behavior, VS2 also possesses a high theoretical capacity. The composite NTO–VS2 nanowire arrays as an additive free 3D anode shows superior electrochemical performance compared to NTO. After 50 (C/10) and 100 (1C) cycles, the charge capacities of NTO–VS2 are maintained, respectively, at 298 and 203mAhg−1, which are much higher than the values of 157 and 93mAhg−1 observed for the same cycled Na2Ti2O5 electrodes. The higher capacity, improved rate capability, and good stability of the composite NTO–VS2 nanowire arrays are due to the structural stability of the Na2Ti2O5 nanowire arrays and the higher capacity and conductivity of the two-dimensional VS2 nanosheets.
A core-shell Na2Ti2O5–VS2 (NTO–VS2) nanowire array with a coating of VS2 on Na2Ti2O5 exhibits superior capacity and rate capability as an anode in sodium-ion batteries compared to the uncoated Na2Ti2O5 (NTO) nanowire array.
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•Na2Ti2O5–VS2 core–shell nanowire array has been explored as an anode in NIB.•The high capacity and conductivity of VS2 nanosheets lead to good performance.•VS2 nanosheet coating leads to enhanced capacity and rate capability.•Na2Ti2O5 nanowire array plays a vital role for cyclability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Three‐dimensional mesoporous TiO2‐Sn/C core‐shell nanowire arrays are prepared on Ti foil as anodes for lithium‐ion batteries. Sn formed by a reduction of SnO2 is encapsulated into TiO2 nanowires and ...the carbon layer is coated onto it. For additive‐free, self‐supported anodes in Li‐ion batteries, this unique core‐shell composite structure can effectively buffer the volume change, suppress cracking, and improve the conductivity of the electrode during the discharge‐charge process, thus resulting in superior rate capability and excellent long‐term cycling stability. Specifically, the TiO2‐Sn/C nanowire arrays display rechargeable discharge capacities of 769, 663, 365, 193, and 90 mA h g−1 at 0.1C, 0.5C, 2C 10C, and 30C, respectively (1C = 335 mA g−1). Furthermore, the TiO2‐Sn/C nanowire arrays exhibit a capacity retention rate of 84.8% with a discharge capacity of over 160 mA h g−1, even after 100 cycles at a high current rate of 10C.
Self‐supported TiO2‐Sn/C core‐shell nanowire array 3D anodes exhibiting superior electrochemical performance are developed using a facile hydrothermal process, followed by a heat treatment process. With this unique nanowire array structure, the aligned TiO2 nanowires with a self‐supported array structure leads to high physical stability, resulting in long cycling stability. The carbon shell suppresses cracking of Sn and improves the conductivity of the electrode, thus contributing to high‐rate cyclability.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
An in situ electrodeposition method is described to fabricate the CdS or/and CdSe quantum dot (QD) sensitized hierarchical TiO2 sphere (HTS) electrodes for solar cell application. Intensity modulated ...photocurrent spectroscopy (IMPS), intensity modulated photovoltage spectroscopy (IMVS) and electrochemical impedance spectroscopy (EIS) measurements are performed to investigate the electron transport and recombination of quantum dot-sensitized solar cells (QDSSCs) based on HTS/CdS, HTS/CdSe, and HTS/CdS/CdSe photoelectrodes. This dynamic study reveals that the CdSe/CdS cosensitized solar cell performs ultrafast electron transport and high electron collection efficiency (98%). As a consequence, a power conversion efficiency as high as 4.81% (J SC = 18.23 mA cm–2, V OC = 489 mV, FF = 0.54) for HTS/CdS/CdSe photoelectrode based QDSSC is observed under one sun AM 1.5 G illumination (100 mW cm–2).
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A concentration-gradient Ni-rich LiNi0.76Co0.1Mn0.14O2 layered oxide cathode has been developed by firing a core/double-shell Ni0.9Co0.10.4Ni0.7Co0.1Mn0.20.5Ni0.5Co0.1Mn0.40.1(OH)2 hydroxide ...precursor with LiOH·H2O, where the Ni-rich interior (core) delivers high capacity and the Mn-rich exterior (shells) provides a protection layer to improve the cyclability and thermal stability for the Ni-rich oxide cathodes. The content of nickel and manganese, respectively, decreases and increases gradually from the center to the surface of each gradient sample particle, offering a high capacity with enhanced surface/structural stability and cyclability. The obtained concentration-gradient oxide cathode exhibits high-energy density with long cycle life in both half and full cells. With high-loading electrode half cells, the concentration-gradient sample delivers 3.3 mA h cm–2 with 99% retention after 100 cycles. The material morphology, phase, and gradient structure are also maintained after cycling. The pouch-type full cells fabricated with a graphite anode delivers high capacity with 89% capacity retention after 500 cycles at C/3 rate.
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TiO2-B nanowire arrays coated with MoS2 nanosheets (TiO2-B/MoS2) have been directly grown on a current collector without any binder or carbon and explored in Li-ion and Na-ion batteries. The 3D ...TiO2-B/MoS2 nanowire array anodes show enhanced capacity and rate capability with good cyclability due to the structural stability of TiO2-B nanowire arrays and the high capacity and conductivity of 2D MoS2 nanosheets.
Bone has multiple functions in animals, such as supporting the body for mobility. The zebrafish skeleton is composed of craniofacial and axial skeletons. It shares a physiological curvature and ...consists of a similar number of vertebrae as humans. Bone degeneration and malformations have been widely studied in zebrafish as human disease models. High‐resolution imaging and different bone properties such as density and volume can be obtained using micro‐computed tomography (micro‐CT). This study aimed to understand the possible changes in the structure and bone mineral density (BMD) of the vertebrae and craniofacial skeleton with age (4, 12 and 24 months post fertilisation mpf) in zebrafish. Our data showed that the BMD in the vertebrae and specific craniofacial skeleton (mandibular arch, ceratohyal and ethmoid plate) of 12 and 24 mpf fish were higher than that of the 4 mpf fish. In addition, we found the age‐dependent increase in BMD was not ubiquitously observed in facial bones, and such differences were not correlated with bone type. In summary, such additional information on the craniofacial skeleton could help in understanding bone development throughout the lifespan of zebrafish.
Micro‐CT images and craniofacial BMD of zebrafish head. The study finds that the age‐dependent increase in BMD was not ubiquitously observed in facial bones, and such differences were not correlated with bone type.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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