59 results on '"Caiyun Nan"'
Search Results
2. Uniform FexNiy Nanospheres: Cost-Effective Electrocatalysts for Nonaqueous Rechargeable Li–O2 Batteries
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Mengwei Yuan, Caiyun Nan, Yan Yang, Genban Sun, Huifeng Li, and Shulan Ma
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Chemistry ,QD1-999 - Published
- 2017
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3. Hollow catalysts through different etching treatments to improve active sites and oxygen vacancies for high-performance Li-O2 battery
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Jiachen Qiu, Yuran Lin, Shuting Zhang, Jie Ma, Yu Zhang, Mengwei Yuan, Genban Sun, and Caiyun Nan
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General Materials Science ,Electrical and Electronic Engineering ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics - Published
- 2023
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4. Single‐Atom‐Mediated Spinel Octahedral Structures for Elevated Performances of Li‐Oxygen Batteries
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Yu Zhang, Shuting Zhang, Junguo Ma, Xin Chen, Caiyun Nan, and Chen Chen
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General Chemistry ,General Medicine ,Catalysis - Published
- 2023
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5. Tuning the oxygen vacancy of mixed multiple oxidation states nanowires for improving Li-air battery performance
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Genban Sun, Di Wang, Wenkai Zhang, Mengwei Yuan, Caiyun Nan, Han Yang, Zemin Sun, Zhenglong Wu, and Huifeng Li
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Battery (electricity) ,Materials science ,Oxide ,Oxygen evolution ,Nanowire ,chemistry.chemical_element ,Electrocatalyst ,Oxygen ,Redox ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Catalysis ,Biomaterials ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Chemical engineering - Abstract
Mixed multiple oxidation states CoMoO4 nanowires (electrocatalysts) with tunable intrinsic oxygen vacancies were fabricated. CoMoO4 with proper oxygen vacancy can be employed to construct a Li-air battery with a high capacity and stable cyclability. This is possible because CoMoO4 contains surface oxygen vacancies, which result in the unit of CoMo bond, that is important for electrocatalysts used in Li-air batteries. Both the experimental and theoretical results demonstrate that the surface oxygen vacancies containing CoMoO4 nanowires have a higher electrocatalytic activity. This shows that the highly efficient electrocatalysts used for Li-air batteries were designed to modify the redox properties of the mixed metal oxide in the catalytic active sites. This successful material design led to an improved strategy for high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities based on the fast formation and extinction of ORR products.
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- 2022
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6. Oxygen Vacancy-Rich RuO2–Co3O4 Nanohybrids as Improved Electrocatalysts for Li–O2 Batteries
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Yu Zhang, Mengwei Yuan, Caiyun Nan, Genban Sun, Chen Chen, Yufeng Li, Jie Ma, Shuting Zhang, and Aijian Huang
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Materials science ,chemistry ,Chemical engineering ,Specific surface area ,chemistry.chemical_element ,General Materials Science ,Lithium ,Density functional theory ,Overpotential ,Porosity ,Oxygen ,Current density ,Catalysis - Abstract
Lithium oxygen (Li-O2) batteries have shown great potential as new energy-storage devices due to the high theoretical energy density. However, there are still substantial problems to be solved before practical application, including large overpotential, low energy efficiency, and poor cycle life. Herein, we have successfully synthesized a RuO2-Co3O4 nanohybrid with a rich oxygen vacancy and large specific surface area. The Li-O2 batteries based on the RuO2-Co3O4 nanohybrid shown obviously reduced overpotential and improved circulatory property, which can cycle stably for more than 100 cycles at a current density of 200 mA g-1. Experimental results and density function theory calculation prove that the introduction of RuO2 can increase oxygen vacancy concentration of Co3O4 and accelerate the charge transfer. Meanwhile, the hollow and porous structure leads to a large specific surface area about 104.5 m2 g-1, exposing more active sites. Due to the synergistic effect, the catalyst of the RuO2-Co3O4 nanohybrid can significantly reduce the adsorption energy of the LiO2 intermediate, thereby reducing the overpotential effectively.
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- 2021
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7. Li Ion Exchanged α-MnO2 Nanowires as Efficient Catalysts for Li-O2 Batteries
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Caiyun Nan, Mengwei Yuan, Jie Ma, and Yu Zhang
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Battery (electricity) ,Materials science ,Ion exchange ,Nanowire ,02 engineering and technology ,General Chemistry ,Lithium sulfate ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Energy storage ,0104 chemical sciences ,Catalysis ,Ion ,Bifunctional catalyst ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,0210 nano-technology - Abstract
Due to the limited energy densities, which could be achieved by lithium-ion cells, Li-O2 batteries, which could provide a promising super energy storage medium, attract much attention nowadays. For its high activity, high storage and low cost, Mn-based oxides have shown versatile application in various batteries. To enhance the cyclability of Li-O2 batteries, here, we synthesized a kind of α-MnO2 nanowires as a bifunctional catalyst for Li-O2 batteries. The particular structure of α-MnO2 reduces the mass transfer resistance of the battery, and the MnO2 nanowires were ion exchanged by saturated lithium sulfate solution so as to further improve the performance of the catalyst. The exchanged α-MnO2 catalyst showed a high discharge specific capacity(6243 mA·h/g at a current density of 200 mA/g) and significantly improved the cyclability up to the 55th cycle(200 mA/g with capacity of 1000 mA·h/g). The results show that the Li ion exchange method is a promising strategy for improving the performance of MnO2 catalyst for Li-O2 batteries.
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- 2020
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8. Engineering Lithium Ions Embedded in NiFe Layered Double Hydroxide Lattices To Activate Laminated Ni 2+ Sites as High‐Efficiency Oxygen Evolution Reaction Catalysts
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Xiaojing Yang, Yuhui Liu, Genban Sun, Caiyun Nan, Mengwei Yuan, Zemin Sun, Di Wang, Huifeng Li, and Kefan Shi
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010405 organic chemistry ,Organic Chemistry ,Intercalation (chemistry) ,Oxygen evolution ,Layered double hydroxides ,chemistry.chemical_element ,General Chemistry ,Overpotential ,engineering.material ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,engineering ,Hydroxide ,Lithium - Abstract
NiFe layered double hydroxides (LDHs) have been denoted as benchmark non-noble-metal electrocatalysts for the oxygen evolution reaction (OER). However, for laminates of NiFe LDHs, the edge sites are active, but the basal plane is inert, leading to underutilization as catalysts for the OER. Herein, for the first time, light and electron-deficient Li ions are intercalated into the basal plane of NiFe LDHs. The results of theoretical calculations and experiments both showed that electrons would be transferred from near Ni2+ to the surroundings of Li+ , resulting in electron-deficient properties of the Ni sites, which would function as "electron-hungry" sites, to enhance surface adsorption of electron-rich oxygen-containing groups, which would enhance the effective activity for the OER. As demonstrated by the catalytic performance, the Li-NiFe LDH electrodes showed an ultralow overpotential of only 298 mV at 50 mA cm-2 , which was lower than that of 347 mV for initial NiFe LDHs and lower than that of 373 mV for RuO2 . Reasonable intercalation adjustment effectively activates laminated Ni2+ sites and constructs the electron-deficient structure to enhance its electrocatalytic activity, which sheds light on the functional treatment of catalytic materials.
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- 2020
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9. Crystal Phase Conversion on Cobalt Oxide: Stable Adsorption toward LiO
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Shuting, Zhang, Jiachen, Qiu, Yu, Zhang, Yuran, Lin, Rong, Liu, Mengwei, Yuan, Genban, Sun, and Caiyun, Nan
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Regulating the structure and morphology of discharge product is one of the key points for developing high performance Li-O
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- 2022
10. Self‐Catalyzed Rechargeable Lithium‐Air Battery by in situ Metal Ion Doping of Discharge Products: A Combined Theoretical and Experimental Study
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Genban Sun, Di Wang, Mengwei Yuan, Shaowei Chen, Qiming Liu, Caiyun Nan, Huifeng Li, Zemin Sun, and Han Yang
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In situ ,Materials science ,Renewable Energy, Sustainability and the Environment ,Inorganic chemistry ,General Materials Science ,Density functional theory ,Environmental Science (miscellaneous) ,Metal ion doping ,Waste Management and Disposal ,Lithium–air battery ,Energy (miscellaneous) ,Water Science and Technology ,Catalysis - Published
- 2022
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11. Quantitative decorating Ni-sites for water-oxidation with the synergy of electronegative sites and high-density spin state
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Yayin Li, Mengwei Yuan, Han Yang, Kefan Shi, Zemin Sun, Huifeng Li, Caiyun Nan, and Genban Sun
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Process Chemistry and Technology ,Catalysis ,General Environmental Science - Published
- 2023
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12. Selective Lithiation–Expansion–Microexplosion Synthesis of Two-Dimensional Fluoride-Free Mxene
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Genban Sun, Han Yang, Liu Lin, Huifeng Li, Mengwei Yuan, Xiaojing Yang, Caiyun Nan, and Zemin Sun
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Physics ,chemistry.chemical_compound ,chemistry ,General Chemical Engineering ,Biomedical Engineering ,Nanomedicine ,General Materials Science ,Nanotechnology ,Fluoride - Abstract
Two-dimensional MXene, a significant member of the two-dimensional family, has attracted much interest in physics, energy evolution, environmental science, and nanomedicine. However, the acute toxi...
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- 2019
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13. Manganese Carbodiimide Nanoparticles Modified with N-Doping Carbon: A Bifunctional Cathode Electrocatalyst for Aprotic Li–O2 Battery
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Genban Sun, Mengwei Yuan, Caiyun Nan, Shuting Zhang, Zemin Sun, Liu Lin, Huifeng Li, Han Yang, and Shulan Ma
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Battery (electricity) ,Nanocomposite ,Materials science ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Manganese ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrocatalyst ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Environmental Chemistry ,0210 nano-technology ,Bifunctional ,Mesoporous material ,Carbon ,Carbodiimide - Abstract
We develop a facile method to prepare a hierarchical mesoporous nanocomposite of manganese carbodiimide nanoparticles modified with N-doping carbon materials (MnNCN/NC). The nanocomposite is endowe...
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- 2019
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14. α-MoC1–x Quantum Dots Encapsulated in Nitrogen-Doped Carbon for Hydrogen Evolution Reaction at All pH Values
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Genban Sun, Han Yang, Heyun Jiang, Huifeng Li, Liu Lin, Mengwei Yuan, Zemin Sun, Caiyun Nan, and Shengsong Ge
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Materials science ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,Doping ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Thermal treatment ,Overpotential ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Nitrogen ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Quantum dot ,Environmental Chemistry ,0210 nano-technology ,Pyrolysis ,Carbon ,Carbon nitride - Abstract
The development of highly effective, universal, and economical electrocatalysts for hydrogen evolution reaction (HER) via structure modulations remains a great challenge. Herein, we propose a novel solidoid nitridation reduction method to synthesize α-MoC1–x quantum dots encapsulated in nitrogen-doped carbon (α-MoC1–x/NC) with a shape like “frog eggs”. Carbon nitride was first prepared by pyrolysis of urea and then mixed with ammonium molybdate tetrahydrate under a temperature-programmed reduction. With the assistance of nitrogen release during thermal treatment, N doping and an ultrathin porous structure were obtained. Benefiting from the strong interaction of α-MoC1–x quantum dots and nitrogen-doped carbon, the α-MoC1–x/NC delivered an outstanding performance toward HER at all pH values. Here, 118 mV, a lower overpotential, is needed to reach 10 mA cm–2 in alkaline solution, and the current density of α-MoC1–x grew much faster than the commercial Pt/C with increased potential. And, this can keep steadil...
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- 2019
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15. Engineering borate modified NiFe layer double hydroxide nanoarrays as 'hydroxyl ions hungry' electrocatalysts for enhanced oxygen evolution
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Caiyun Nan, Genban Sun, Shengsong Ge, Huifeng Li, Run Long, Xiaojing Yang, Yutong Wang, Liu Lin, Heyun Jiang, Mengwei Yuan, and Zemin Sun
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Materials science ,chemistry.chemical_element ,Overpotential ,engineering.material ,010402 general chemistry ,01 natural sciences ,Catalysis ,Ion ,chemistry.chemical_compound ,Materials Chemistry ,Boron ,010405 organic chemistry ,Metals and Alloys ,Layered double hydroxides ,Oxygen evolution ,General Chemistry ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,Chemical engineering ,Electrode ,Ceramics and Composites ,engineering ,Hydroxide - Abstract
NiFe layered double hydroxides (NiFe-LDHs) have been regarded as significant electrocatalysts for the oxygen evolution reaction (OER). However, their overpotential must still be further reduced to enable commercial applications. Herein, a promising and highly effective "hydroxyl ions hungry" electrode structure was prepared for the first time via a two-step hydrothermal reaction procedure to enhance the surface adsorption kinetics to obtain an ultralow overpotential. The electrode exhibits OER activity with ultralow overpotentials of 203 mV and 293 mV at the current densities of 10 mA cm-2 and 100 mA cm-2, respectively, in 1.0 M KOH. These results reveal an important way to improve the catalytic performance in an alkaline medium.
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- 2019
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16. Two-dimensional β-cobalt hydroxide phase transition exfoliated to atom layers as efficient catalyst for lithium-oxygen batteries
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Shulan Ma, Caiyun Nan, Huifeng Li, Liu Lin, Genban Sun, Zemin Sun, Mengwei Yuan, and Xiaojing Yang
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Phase transition ,Materials science ,Cobalt hydroxide ,General Chemical Engineering ,Oxygen evolution ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Exfoliation joint ,Oxygen ,0104 chemical sciences ,Catalysis ,Chemical engineering ,chemistry ,Atom ,Electrochemistry ,Lithium ,0210 nano-technology - Abstract
Metal-oxygen batteries, especially Li-oxygen batteries (LOBs), have attracted tremendous research attentions in the past decades. It is necessary to design novel cost-effective catalysts in the development of high performance rechargeable LOBs. Herein, we prepare the atom-layered two-dimensional (2D) β -Co(OH) 2 nanosheets (AL- β -Co(OH) 2 ) via phase transition of layered α- Co(OH) 2 nanosheets ( α- Co(OH) 2 ) in a mild wet chemical process. The thickness of AL- β- Co(OH) 2 is less than 1.5 nm. It is the first time of using atom-layered β -Co(OH) 2 in the system of LOBs and this material shows outstanding catalytic performance. The AL- β -Co(OH) 2 nanosheets as electrocatalysts in LOBs can better reduce the over-potential, enhance the specific capacity and improve cycling capability. It demonstrates a high initial capacity 11841 mAh g −1 at a current density of 100 mA g −1 . It displays long cycle stability more than 70 cycles with a capacity restriction of 1000 mAh g −1 . These results suggest that this strategy for designing oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts via exfoliation of materials to atom-layered level could be a promising way to improve the performance of LOBs.
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- 2018
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17. Porous Co3O4 nanorods anchored on graphene nanosheets as an effective electrocatalysts for aprotic Li-O2 batteries
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Huifeng Li, Shulan Ma, Caiyun Nan, Mengwei Yuan, Genban Sun, and Yan Yang
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Battery (electricity) ,Nanocomposite ,Materials science ,Graphene ,General Physics and Astronomy ,02 engineering and technology ,Surfaces and Interfaces ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Hydrothermal circulation ,0104 chemical sciences ,Surfaces, Coatings and Films ,law.invention ,Chemical engineering ,law ,Nanorod ,0210 nano-technology ,Porosity ,Current density ,Faraday efficiency - Abstract
The large over-potential during the battery operation is a great obstacle for the application of Li-O2 batteries. The porous structure and electrical conductivity of the electrocatalysts are significant for the electrocatalytic performance of Li-O2 batteries. In this work, a porous Co3O4/GN nanocomposite (Co3O4 nanorods anchored on graphene nanosheets) is prepared via a facile hydrothermal method assisted with heat treatment. The unique structure of Co3O4/GN endows efficient electrocatalystic activity for Li-O2 batteries. In comparison to the Co3O4, the Co3O4/GN demonstrates a better cycle performance showing more than 40 cycles with a 1500 mAh g−1 capacity limit strategy at a current density of 300 mA g−1, and a reduced over-potential of 110 mV at high current density (1200 mA g−1). The Co3O4/GN also displays a high initial specific capacity (7600 mAh g−1) and a good reversibility in full cycle with a coulombic efficiency of 99.8% in the first cycle. The impressed cyclability, specific capacity, rate performance, and low over-potentials indicate that the as-prepared Co3O4/GN nanocomposite is a promising catalyst candidate for reversible Li-O2 batteries.
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- 2018
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18. Magnetic phase transition and large room temperature magnetoresistance in Ni doped FeRh films
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Liang Wu, Yujun Zhang, Jiahui Chen, Jing Ma, and Caiyun Nan
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Phase transition ,Materials science ,Condensed matter physics ,Magnetoresistance ,Spintronics ,Mechanical Engineering ,Doping ,Metals and Alloys ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Magnetic field ,Condensed Matter::Materials Science ,Ferromagnetism ,Mechanics of Materials ,0103 physical sciences ,Cavity magnetron ,Materials Chemistry ,Antiferromagnetism ,010306 general physics ,0210 nano-technology - Abstract
We have investigated the structural, magnetic and electrical transport properties of the Ni doped FeRh films prepared by magnetron co-sputtering. A large magetoresistance of 35%, induced by a reversible antiferromagnetic to ferromagnetic phase transition, is obtained at room temperature with only 1 mol.% Ni addition. Magnetic field is revealed to have an equivalent effect as temperature to drive the magnetic phase transition. Moreover, the way to realize a nonvolatile room temperature magetoresistance effect is also discussed. These results give FeRh the possibility of technological application in the spintronic field at room temperature, which are referential to other material systems with a first-order magnetic phase transition.
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- 2018
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19. The in situ growth of ultrathin Fcc-NiPt nanocrystals on graphene for methanol and formic acid oxidation
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Genban Sun, Shulan Ma, Mengwei Yuan, Huifeng Li, Zemin Sun, Liu Lin, and Caiyun Nan
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Materials science ,Nanocomposite ,Graphene ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrocatalyst ,01 natural sciences ,0104 chemical sciences ,law.invention ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,law ,Methanol ,0210 nano-technology ,Bifunctional ,Nanosheet - Abstract
Due to the increasing demand for energy, improving the current density of fuel cells is an urgent issue. Here we report a bifunctional electrocatalyst for fuel cells involving methanol or formic acid oxidation. A nanocomposite consisting of 7.2 nm NiPt nanocrystals, which are grown in situ on graphene nanosheets (NiPt/GN), has been prepared via a solution thermal decomposition method. The NiPt/GN nanocatalyst presents specific activities as high as 41.1 mA cm-2 and 42.9 mA cm-2 for methanol oxidation and formic acid oxidation, respectively, outperforming most reported catalysts. Moreover, it retains 76.3% of this activity after 900 cycles of methanol oxidation. Additionally, in comparison with general NiPt nanoparticles, the NiPt/GN nanocatalyst shows higher electrocatalytic activity in methanol and formic acid oxidation. All these results indicate that ultrathin NiPt nanocrystals grown in situ on graphene nanosheet substrates can significantly improve performance as a bifunctional electrocatalyst.
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- 2018
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20. Significant enhancement of the performance of hydrogen evolution reaction through shape-controlled synthesis of hierarchical dendrite-like platinum
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Liu Lin, Jinlu He, Huifeng Li, Mengwei Yuan, Zemin Sun, Run Long, Genban Sun, Shulan Ma, and Caiyun Nan
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Materials science ,Morphology (linguistics) ,Renewable Energy, Sustainability and the Environment ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Overpotential ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Catalysis ,Template ,chemistry ,Chemical engineering ,General Materials Science ,Hydrogen evolution ,Dendrite (metal) ,0210 nano-technology ,Polarization (electrochemistry) ,Platinum - Abstract
Herein, hierarchical dendrite-like Pt crystals with a distinct morphology were synthesized via a facile one-pot method without any templates. Formation of this hierarchical structure is dependent on the reaction duration. Interestingly, different hierarchical structures show different catalytic activities. After a 12 hour reaction, tertiary structures of Pt are formed, which can act as outstanding catalysts in the hydrogen evolution reaction (HER). The onset potential of this dendrite-like Pt catalyst for the HER in a 0.5 M H2SO4 solution is 15 mV, which outperforms that of commercial Pt/C (30 mV). Moreover, it shows significantly improved stability for HER as the polarization curve after 10 000 cycles retains a similar performance as in the initial test; this results in a loss of only 2.6% of its initial current density at an overpotential of 0.05 V. The distinct hierarchical dendrite-like structures are maintained after cycling and current–time tests, which can be responsible for the excellent performance of this catalyst.
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- 2018
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21. Optimized Self‐Templating Synthesis Method for Highly Crystalline Hollow Cu 2 O Nanoboxes
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Yu Zhang, Jiqing Jiao, Zheng Chen, Caiyun Nan, Chao Zhang, Weng-Chon Cheong, Chen Chen, and Ruoyun Dai
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Polyhedron ,Materials science ,Chemical engineering ,General Materials Science ,General Chemistry - Published
- 2020
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22. In-situ growth of ultrathin cobalt monoxide nanocrystals on reduced graphene oxide substrates: an efficient electrocatalyst for aprotic Li-O
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Mengwei, Yuan, Liu, Lin, Yan, Yang, Caiyun, Nan, Shulan, Ma, Genban, Sun, and Huifeng, Li
- Abstract
Large over-potentials during battery operation remain a big obstacle for aprotic Li-O
- Published
- 2017
23. High-performance lithium/sulfur cells with a bi-functionally immobilized sulfur cathode
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Elton J. Cairns, Zhan Lin, Jinghua Guo, Caiyun Nan, Junfa Zhu, and Yifan Ye
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Materials science ,Renewable Energy, Sustainability and the Environment ,Inorganic chemistry ,Oxide ,chemistry.chemical_element ,Electrolyte ,Sulfur ,Cathode ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,General Materials Science ,Lithium ,Electrical and Electronic Engineering ,Polysulfide ,Faraday efficiency ,Sulfur utilization - Abstract
Lithium/sulfur (Li/S) cells have a theoretical specific energy five times higher than that of lithium-ion (Li-ion) cells (2600 vs. ~500 Wh kg−1). The conventional Li/S cells that use an organic liquid electrolyte are short-lived with low coulombic efficiency due to the polysulfide shuttle. We herein design carbon-coated NanoLi2S (NanoLi2S@carbon) composites, which consist of Li2S nanoparticles as the core and a carbon coating as the shell. The carbon shell prevents the NanoLi2S core from directly contacting the liquid electrolyte, which improves the performance of Li/S cells to provide longer cycle life and high sulfur utilization. The cyclability of Li/S cells is further enhanced by mixing the core–shell NanoLi2S@carbon composites with graphene oxide, which chemically immobilizes polysulfides in the cathode through their functional groups. The resulting Li/S cell shows an initial specific discharge capacity of 1263 mAh g−1 (normalized to sulfur) at the C/10 rate and a capacity retention of 65.4% after 200 cycles. The capacity decay mechanism during cycling is also characterized in detail using near edge X-ray absorption fine structure (NEXAFS) spectra.
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- 2014
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24. Fabrication of 1D nickel sulfide nanocrystals with high capacitances and remarkable durability
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Zhuo Wang, Dingsheng Wang, Yadong Li, and Caiyun Nan
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Fabrication ,Nickel sulfide ,Materials science ,General Chemical Engineering ,Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,Sulfur ,Capacitance ,Durability ,Nanomaterials ,Solvent ,chemistry.chemical_compound ,chemistry ,Nanocrystal - Abstract
Nickel sulfide (NiS) materials with a different 1D structure are successfully synthesized by strictly controlling the reaction time and temperature, using dodecanethiol as both solvent and sulfur source. The formation of the NiS nanomaterials results from a “dispersion–decomposition” mechanism. Remarkably, 1D NiS electrode materials show super specific capacitance and stability.
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- 2014
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25. Voltage-driven hysteretic changes in magnetization in multiferroic Co/BTO composite thin films
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Jia Mian Hu, Liang Wu, Yuan-Hua Lin, Caiyun Nan, Li Shu, Yao Gao, and Jing Ma
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Kerr effect ,Materials science ,Condensed matter physics ,Magnetometer ,Physics::Optics ,General Physics and Astronomy ,Surfaces and Interfaces ,General Chemistry ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Pulsed laser deposition ,law.invention ,Condensed Matter::Materials Science ,Magnetic anisotropy ,Magnetization ,Magneto-optic Kerr effect ,law ,Condensed Matter::Superconductivity ,Multiferroics ,Thin film - Abstract
Multiferroic Co/BaTiO3 layered composite thin films were grown on Nb-doped SrTiO3 single crystal by pulse laser deposition, in which the polycrystalline Co film was annealed under magnetic field to induce in-plane uniaxial magnetic easy axis. Voltage-induced magnetization changes along and perpendicular to the easy axis were measured by Magneto-Optical Kerr effect (MOKE) magnetometer without applied magnetic field. These changes in magnetization could be due to magnetoelectric coupling between Co and BaTiO3, and to possibly electro-optical effect of BTO if the MOKE laser could penetrate the top Co film. After excluding the electro-optical interference by analyzing the experimental results within an optical model, a hysteric loop of magnetization versus voltage is identified with a relative change in magnetization of about 8%.
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- 2014
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26. Nanoscale Coating of LiMO2 (M = Ni, Co, Mn) Nanobelts with Li+-Conductive Li2TiO3: Toward Better Rate Capabilities for Li-Ion Batteries
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Jun Lu, Caiyun Nan, Qing Peng, Weiyang Wang, Yadong Li, and Lihong Li
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Battery (electricity) ,Chemistry ,Diffusion ,Doping ,Analytical chemistry ,Nanotechnology ,General Chemistry ,engineering.material ,Biochemistry ,Catalysis ,Cathode ,Ion ,law.invention ,Colloid and Surface Chemistry ,Coating ,law ,engineering ,Layer (electronics) ,Nanoscopic scale - Abstract
By using a novel coating approach based on the reaction between MC(2)O(4)·xH(2)O and Ti(OC(4)H(9))(4), a series of nanoscale Li(2)TiO(3)-coated LiMO(2) nanobelts with varied Ni, Co, and Mn contents was prepared for the first time. The complete, thin Li(2)TiO(3) coating layer strongly adheres to the host material and has a 3D diffusion path for Li(+) ions. It is doped with Ni(2+) and Co(3+) ions in addition to Ti(4+) in LiMO(2), both of which were found to favor Li(+)-ion transfer at the interface. As a result, the coated nanobelts show improved rate, cycling, and thermal capabilities when used as the cathode for Li-ion battery.
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- 2013
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27. Enhancing ionic conductivity of Li0.35La0.55TiO3 ceramics by introducing Li7La3Zr2O12
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Mian Huang, Chen Kai, Yuanhua Lin, Yang Shen, and Caiyun Nan
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Materials science ,General Chemical Engineering ,Inorganic chemistry ,Sintering ,Conductivity ,Lithium-ion battery ,Dielectric spectroscopy ,visual_art ,Phase (matter) ,Electrochemistry ,visual_art.visual_art_medium ,Ionic conductivity ,Grain boundary ,Ceramic ,Composite material - Abstract
Li7La3Zr2O12 (LLZO) powder was mixed with and thus introduced into Li0.35La0.55TiO3 (LLTO) ceramics. After high-temperature sintering LLZO phase disappeared. The cooperative introduction of Li, La and Zr elements into LLTO might modify the grain boundary region and thus change the electrical properties of the grain boundary, leading to the conductivity enhancement. The LLTO ceramics sintered at 1350 °C with 10 wt% LLZO powder introduced in the starting materials exhibit a high total conductivity of near 10−4 S/cm and a grain boundary conductivity of 1.1 × 10−4 S/cm at room temperature.
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- 2012
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28. Single crystalline lithium titanate nanostructure with enhanced rate performance for lithium ion battery
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Caiyun Nan, Qing Peng, Jun Lu, and Yadong Li
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Materials science ,Nanostructure ,Renewable Energy, Sustainability and the Environment ,Spinel ,Inorganic chemistry ,Energy Engineering and Power Technology ,engineering.material ,Electrochemistry ,Lithium-ion battery ,Hydrothermal circulation ,Ion ,chemistry.chemical_compound ,chemistry ,Nanocrystal ,engineering ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Lithium titanate - Abstract
Here we report the synthesis and electrochemical performance of 40 nm near-uniform lithium titanate (Li4Ti5O12) single crystals. The cubic spinel Li4Ti5O12 nanocrystals are transformed without size changes at 400 °C from cubic NaCl type (Li0.4H0.6)2TiO3 nanocrystals that are prepared from hydrothermal synthesized α-Li2TiO3. The prepared Li4Ti5O12 nanocrystals show reduced charge-transfer impedance and exhibit favorable performance under high current charging/discharging due to the reduced Li+ ion diffusion path.
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- 2012
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29. From Single-Component Nanowires to Composite Nanotubes
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Yadong Li, Yina Zhu, Ruji Wang, Wei Chen, Qing Peng, and Caiyun Nan
- Subjects
Work (thermodynamics) ,Materials science ,Single component ,Diffusion ,Composite number ,Nanowire ,General Materials Science ,Nanotechnology ,General Chemistry ,Thermal treatment ,Condensed Matter Physics ,Solution phase ,Ion - Abstract
In this work, a facile, solution phase route using Co(OH)x(CO3)y nanowires as precursors was developed to fabricate SnO2/Co(OH)x+2e(CO3)y−e, and then they were transformed into SnO2/Co3O4 composite nanotubes by a simple thermal treatment process, which had great advantages in controlling their elemental ratios and the size of inner diameters. The mechanism is systematically discussed, which offers a clue that “diffusion” could be used as a driving force for the formation of nanotubes with different components, and single-component nanowires with replaceable negative ions may serve as good building blocks. TiO2/Co3O4 nanotubes were also successfully achieved to demonstrate the generality of the methodology, which is helpful for scientists to exploit novel functional materials with new properties and applications.
- Published
- 2011
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30. Synthesis of LiV3O8 nanorods and shape-dependent electrochemical performance
- Author
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Peng Zhao, Xiaoling Xiao, Caiyun Nan, Yadong Li, Dingsheng Wang, and Jun Lu
- Subjects
Materials science ,Scanning electron microscope ,Mechanical Engineering ,Nanowire ,Nanotechnology ,Condensed Matter Physics ,Electrochemistry ,Hydrothermal circulation ,Crystal ,Nanocrystal ,Mechanics of Materials ,Transmission electron microscopy ,General Materials Science ,Nanorod - Abstract
Shape control of nanocrystals has become an indispensable part in material research, such as developing new battery raw materials and synthesizing high activity catalysts. In this work, one-dimensional LiV3O8 nanorods have been fabricated by high temperature solid-state reaction using V2O5 nanowires as precursors obtained via a hydrothermal method. The as-prepared LiV3O8 nanorods were characterized by x-ray diffraction, transmission electron microscopy, scanning electron microscopy, and galvanostatic tests, compared with LiV3O8 samples synthesized by the traditional one-step solid-state method. The results show that LiV3O8 nanorods exhibited better electrochemical performance than those synthesized by the traditional method, indicating that a different shape will lead to huge distinctions in electrochemical properties. This work demonstrates that Li-insertion/deintercalation dynamics might be crystal morphology-sensitive.
- Published
- 2011
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31. Correction: Corrigendum: Full 180° Magnetization Reversal with Electric Fields
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J. J. Wang, J. M. Hu, Long Qing Chen, J. X. Zhang, J. Ma, and Caiyun Nan
- Subjects
010302 applied physics ,Engineering drawing ,Multidisciplinary ,Work (electrical) ,Computer science ,Electric field ,0103 physical sciences ,Section (typography) ,Magnetization reversal ,02 engineering and technology ,021001 nanoscience & nanotechnology ,0210 nano-technology ,01 natural sciences - Abstract
Scientific Reports 4: Article number: 7507; published online: 16 December 2014; updated: 25 February 2016. This Article contains a typographical error in a grant number in the Acknowledgements section. “This work was supported by the NSF of China (Grant Nos. 51332001, 11234005, 51472140 and 51221291), and the NSF (Grant No: DMR-1410714, DMR-0820404, and DMR-1210588).
- Published
- 2016
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32. Selective Lithiation-Expansion-Microexplosion Synthesis of Two-Dimensional Fluoride-Free Mxene.
- Author
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Zemin Sun, Mengwei Yuan, Liu Lin, Han Yang, Caiyun Nan, Huifeng Li, Genban Sun, and Xiaojing Yang
- Published
- 2019
- Full Text
- View/download PDF
33. A simple model for thermal conductivity of carbon nanotube-based composites
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Z. Shi, Caiyun Nan, and Yuanhua Lin
- Subjects
Nanotube ,SIMPLE (dark matter experiment) ,Materials science ,General Physics and Astronomy ,Carbon nanotube ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Aspect ratio (image) ,law.invention ,Optical properties of carbon nanotubes ,Carbon nanotube metal matrix composites ,Condensed Matter::Materials Science ,Thermal conductivity ,Potential applications of carbon nanotubes ,law ,Physical and Theoretical Chemistry ,Composite material - Abstract
A quite simple formula for the thermal conductivity enhancement in carbon nanotube composites is presented based on a conventional model. This simple formula predicts much higher thermal conductivity enhancement even in the dilute case of the carbon nanotubes, due to ultrahigh thermal conductivity and aspect ratio of the carbon nanotubes. By applying this model to nanotube suspensions recently reported in the literature, we show that the conventional model is still valid for the nanotube-based composites.
- Published
- 2003
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34. Dielectric behavior of Li and Ti co-doped NiO/PVDF composites
- Author
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Caiyun Nan, Zhi-Min Dang, Junbo Wu, and Li-Zhen Fan
- Subjects
Materials science ,Non-blocking I/O ,Composite number ,General Physics and Astronomy ,Dielectric ,Polyvinylidene fluoride ,law.invention ,Boundary layer ,chemistry.chemical_compound ,Capacitor ,Percolation theory ,chemistry ,Electrical resistivity and conductivity ,law ,Physical and Theoretical Chemistry ,Composite material - Abstract
The dielectric behavior of two kinds of Li and Ti co-doped NiO (LTNO)/polyvinylidene fluoride (PVDF) composite was studied at various different frequencies and temperatures. The effective dielectric constant of the percolative composite at 100 Hz is very high, i.e., e eff ≈600, which is 60 times higher than that of the PVDF. The results also show that there is a remarkable difference in the dielectric constant of the composites with different LTNO fillers. Boundary layer capacitor effect and percolation theory can be used to explain the experimental results.
- Published
- 2003
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35. Analysis of AC electrical properties of (Li and Ti)-doped NiO
- Author
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Yuan Deng, Junbo Wu, Yuanhua Lin, Shujin Zhao, J. Nan, and Caiyun Nan
- Subjects
Materials science ,Constant phase element ,Mechanical Engineering ,Doping ,Non-blocking I/O ,Analytical chemistry ,Condensed Matter Physics ,Microstructure ,Dielectric spectroscopy ,Mechanics of Materials ,General Materials Science ,Spectroscopy ,RC circuit ,Electrical impedance - Abstract
(Li and Ti)-doped NiO samples were prepared by the citrate precursor method followed by a sintered process, and impedance spectroscopy (IS) of these samples was measured as a function of frequency and temperature. Accordingly, the impedance spectra exhibit two depressed semicircles when the Ti content is more than 5 mol.%, which is corresponding to the core–shell microstructure. The simple resistor–capacitor (RC) effective circuit and the modified effective circuit (the capacitor in the RC circuit is replaced by a constant-phase element (CPE)) were used to fit the experimental data. And it is indicated that the CPE element is an effective tool to analyze IS.
- Published
- 2003
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- View/download PDF
36. Synthesis and optical properties of tetrapod-like zinc oxide nanorods
- Author
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Caiyun Nan, Q.K. Li, Y. Zhang, and Y. Dai
- Subjects
Photoluminescence ,biology ,Chemistry ,Scanning electron microscope ,Analytical chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,Zinc ,biology.organism_classification ,Green emission ,Tetrapod ,Nanocrystal ,Transmission electron microscopy ,Nanorod ,Physical and Theoretical Chemistry - Abstract
Uniform tetrapod-like zinc oxide (T-ZnO) nanorods were produced in bulk quantity by oxidation of Zn powders. Field-emission scanning electron microscope and transmission electron microscopy investigations showed that T-ZnO nanorods were high-quality nanocrystals. The length of legs of T-ZnO nanorods was 2–3 μm and the edge size of centering nucleus was 70–150 nm. The growth of T-ZnO nanorods was controlled by a vapor–solid (VS) mechanism. UV emission peak at ∼380 nm and green emission peak at ∼495 nm were observed at room temperature, which was assigned to the near band-edge emission and the deep-level emission, respectively.
- Published
- 2002
- Full Text
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37. A magnetoelectric logic gate
- Author
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Yuan-Hua Lin, Caiyun Nan, Jia Mian Hu, and Li Zheng
- Subjects
Magnetoresistive random-access memory ,Pass transistor logic ,Magnetic logic ,business.industry ,Computer science ,Logic family ,Electrical engineering ,NAND gate ,Condensed Matter Physics ,CMOS ,Logic gate ,General Materials Science ,business ,XOR gate ,Hardware_LOGICDESIGN - Abstract
Magnetic tunnel junctions (MTJs) [1, 2] have been used for magnetic memory (usually known as MRAM) and sen-sor applications [3, 4], while they also offer opportunities for novel logic devices, either employed as the spin-logic de-vices [5–7], or combining with complementary metal oxide semiconductor (CMOS) transistors in hybrid MTJ/CMOS logic circuits [8–11]. In such MTJ-based logic devices, the high and low resistance states, corresponding respectively to the antiparallel and parallel magnetic configuration in the MTJ unit, are related to the Boolean 1 or 0, and different logic functions can then be defined. Compared with current CMOS logic devices, the MTJ-based magnetic logic has several significant advantages such as nonvolatile in-puts/outputs, non-destructive readout and the possibility of fast operation and run-time reconfigurability [5–7]. How-ever, the high power consumption associated with the cur-rent-induced magnetization switching in the MTJ unit turns into a major drawback of such magnetic logic devices [11], since the accompanying overheating imposes limitations on the performance optimization of the devices and will be-come more severe with increased integration [12]. Therefore, it is of paramount importance to reduce the energy con-sumption in the switching process before industrial applica-tions of such MTJ-based logic devices. Until recently the idea to make purely electric-field-controlled devices [13] has offered a promising route to this goal, i.e., the electric-field-controlled magnetic logic devices, in which electric fields instead of currents are di-rectly used to induce the magnetization switching during the input process, and thus cause much less Joule heating. As an early example, the concept of a magnetoelectric (ME) XOR logic cell [14] was proposed by exploiting ME switching of exchange bias [15]. In this letter, we present a novel concept of electric-field-controlled ME-logic based on the strain-mediated ME coupling in multiferroic ME composites [16], namely, a strain-mediated ME-logic, which is nonvolatile, low power-consumed and compatible with current semiconductor devices. Two possible designs of such ME-logic devices are introduced, which can either be preset as a NOR, NOT, or NAND gate separately, or be electronically configured to perform the logical NOR, NOT, or NAND function at run-time.
- Published
- 2010
- Full Text
- View/download PDF
38. Temperature dependence of magnetoelectric coupling in FeBSiC/PZT/FeBSiC laminates
- Author
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Jun Xian Ye, Jia Mian Hu, Jian Nan Ma, Jing Ma, Ming Feng, Qiming Zhang, Li Zheng, and Caiyun Nan
- Subjects
Materials science ,Volume fraction ,Composite number ,General Physics and Astronomy ,Curie temperature ,Coupling (piping) ,Magnetostriction ,Composite material ,Atmospheric temperature range ,Elastic modulus ,Piezoelectricity - Abstract
Temperature dependence of the magnetoelectric (ME) coefficient was studied for FeBSiC/Pb(Zr, Ti)O3(PZT)/FeBSiC laminates over temperature range of −35 ∼ 85 °C. The variation in ME coefficient as a function of temperature was found to be significantly dependent on the volume fraction of FeBSiC layers and the lateral dimension of the laminate composites. Our results show that minimum number of FeBSiC layer with smaller lateral dimension can provide more stable ME coefficient in wide temperature range, due to the competition of the effects of temperature influenced piezoelectricity, magnetostriction, and mechanical properties of the constituents and the interfacial bonding layer. This finding indicate that it is beneficial to promote miniaturization of the ME composite based devices in view of temperature stability.
- Published
- 2014
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- View/download PDF
39. Predicting effective magnetoelectric response in magnetic-ferroelectric composites via phase-field modeling
- Author
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Tiannan Yang, Jia Mian Hu, Caiyun Nan, and Long Qing Chen
- Subjects
Condensed Matter::Materials Science ,Magnetization ,Materials science ,Physics and Astronomy (miscellaneous) ,Electric field ,Constitutive equation ,Magnetoelectric effect ,Physics::Optics ,Dielectric ,Composite material ,Ferroelectricity ,Piezoelectricity ,Coupling coefficient of resonators - Abstract
A phase-field model coupled with constitutive equations is formulated to investigate the magnetoelectric cross-coupling in magnetic-ferroelectric composites. The model allows us to obtain equilibrium piezoelectric, piezomagnetic, dielectric, and magnetoelectric properties under a given magnetic or electric field, from the local distributions of polarization, magnetization, and strain in the composites. As an example, effective magnetoelectric coupling coefficient, i.e., magnetic-field-induced voltage output (or changes in polarization), of the CoFe2O4-BaTiO3 composites is numerically calculated. Influences of the phase connectivity and the phase fraction of the composites on the magnetoelectric coupling coefficient are discussed.
- Published
- 2014
- Full Text
- View/download PDF
40. Evaluating the electro-optical effect in alternating current-voltage-modulated Kerr response for multiferroic heterostructures
- Author
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Li Shu, Ya Gao, Li Zheng, Jia Mian Hu, Caiyun Nan, Yang Shen, and Yuanhua Lin
- Subjects
Materials science ,Kerr effect ,Condensed matter physics ,Magnetometer ,Physics::Optics ,General Physics and Astronomy ,Heterojunction ,Signal ,Ferroelectricity ,law.invention ,General Relativity and Quantum Cosmology ,Condensed Matter::Materials Science ,Magnetization ,Magneto-optic Kerr effect ,law ,Multiferroics ,Nonlinear Sciences::Pattern Formation and Solitons - Abstract
Voltage-modified Kerr magnetometer has been widely used to measure the voltage-modulated magnetic properties in multiferroic magnetic/ferroelectric heterostructures, where the Kerr signal change is considered to be in proportion to magnetization change, i.e., the magneto-optical Kerr effect. However, the total Kerr signal changes might also incorporate contribution from the electro-optical effect of the ferroelectric layer in the multiferroic heterostructure. Here, we evaluate quantitatively, by combining analytical calculations with experimental observations, such electro-optical contribution in the total voltage-induced Kerr signal changes with comparison to those from Kerr effect via converse magnetoelectric coupling. Influences of several parameters, including the magnetic film thickness on the Kerr signal changes, are also investigated.
- Published
- 2013
- Full Text
- View/download PDF
41. Converse magnetoelectric coupling in NiFe/Pb(Mg1/3Nb2/3)O3–PbTiO3 nanocomposite thin films grown on Si substrates
- Author
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Ming Feng, Li Shu, Jianjun Wang, Jia Mian Hu, Li Zheng, and Caiyun Nan
- Subjects
Magnetization ,Spin coating ,Kerr effect ,Nanocomposite ,Nuclear magnetic resonance ,Nanolithography ,Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Multiferroics ,Sputter deposition ,Thin film - Abstract
Multiferroic NiFe (∼30 nm)/Pb(Mg1/3Nb2/3)O3–PbTiO3(PMN–PT, ∼220 nm) bilayered thin films were grown on common Pt/Ti/SiO2/Si substrates by a combination of off-axis magnetron sputtering and sol-gel spin-coating technique. By using AC-mode magneto-optical Kerr effect technique, the change in the Kerr signal (magnetization) of the NiFe upon applying a low-frequency AC voltage to the PMN–PT film was in situ acquired at zero magnetic field. The obtained Kerr signal versus voltage loop essentially tracks the electromechanical strain curve of the PMN–PT thin film, clearly demonstrating a strain-mediated converse magnetoelectric coupling, i.e., voltage-modulated magnetization, in the NiFe/PMN–PT nanocomposite thin films.
- Published
- 2013
- Full Text
- View/download PDF
42. Significant enhancement in energy density of polymer composites induced by dopamine-modified Ba0.6Sr0.4TiO3 nanofibers
- Author
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Penghao Hu, Yuanhua Lin, Yu Song, Yang Shen, Ming Li, and Caiyun Nan
- Subjects
chemistry.chemical_compound ,Materials science ,Nanolithography ,Nanocomposite ,Physics and Astronomy (miscellaneous) ,chemistry ,Nanofiber ,Antiferroelectricity ,Surface modification ,Dielectric ,Composite material ,Polyvinylidene fluoride ,Electrospinning - Abstract
Ba0.6Sr0.4TiO3 (BST) nanofibers prepared via electrospinning and modified by dopamine are used as dielectric fillers in polyvinylidene fluoride (PVDF)-based composites. With 4.4 vol. % of BST nanofibers, the extractable energy density of the BST/PVDF composites is more than doubled as compared with pure PVDF matrix. Such significant enhancement is attributed to the combined effect of both surface modification by dopamine and large aspect ratio of the BST nanofibers. Paraelectric or anti-ferroelectric fillers of large aspect ratio may serve as a general strategy for enhanced electric energy density in polymer composites.
- Published
- 2012
- Full Text
- View/download PDF
43. Thickness-dependent converse magnetoelectric coupling in bi-layered Ni/PZT thin films
- Author
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Li Shu, Yuanhua Lin, Caiyun Nan, Ya Gao, Li Zheng, Yang Shen, and Jia Mian Hu
- Subjects
Thickness dependent ,Kerr effect ,Materials science ,Thin layers ,General Physics and Astronomy ,chemistry.chemical_element ,Nickel ,Magnetization ,Nuclear magnetic resonance ,chemistry ,Coupling (piping) ,Thin film ,Composite material ,Bi layered - Abstract
The converse magnetoelectric (ME) effect was investigated in bi-layered Ni/Pb(Zr0.52Ti0.48)O3 (PZT) thin films grown on Si substrates, with different thicknesses of Ni thin layers. By using an AC-mode magneto-optical Kerr effect method, it was revealed that the electric-voltage induced magnetization variation was dependent on the thickness of the Ni thin layer. The results showed that the Ni/PZT bilayered films with thick (about 40 nm) Ni films presented a dominative strain mediated ME coupling, whereas an interface-charge and strain co-mediated ME coupling might coexist in the Ni/PZT bilayered films with decreasing thickness (e.g., about 10 nm) of Ni films.
- Published
- 2012
- Full Text
- View/download PDF
44. A simple method for direct observation of the converse magnetoelectric effect in magnetic/ferroelectric composite thin films
- Author
-
Yi Zhang, Jia Mian Hu, Li Shu, Yang Shen, Yuanhua Lin, Caiyun Nan, Ya Gao, and Li Zheng
- Subjects
Coupling ,Magnetization ,Materials science ,Nuclear magnetic resonance ,Condensed matter physics ,Composite number ,Magnetoelectric effect ,General Physics and Astronomy ,Thin film ,Ferroelectricity ,Magnetic field ,Voltage - Abstract
A novel characterization method is presented to directly observe the pure converse magnetoelectric (ME) effect, i.e., the electric-field modification of magnetization, in composite magnetic/ferroelectric (FE) layered thin films. A low-frequency AC electric-voltage, rather than DC voltage bias, is applied to the FE thin films to minimize the leakage current, whereby the possible side effect of heating can be avoided. In particular, by synchronizing the frequency of the Kerr signal detector to the AC actuation voltage bias, the voltage-induced change of the magnetization in the magnetic films can be in situ recorded even under zero external magnetic fields. For illustration, this method is applied to two similar magnetic/FE composite thin films, with significant strain-mediated converse ME coupling being demonstrated in both cases.
- Published
- 2011
- Full Text
- View/download PDF
45. Switchable voltage control of the magnetic coercive field via magnetoelectric effect
- Author
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Yuanhua Lin, Jing Ma, Jing Wang, Li Zheng, Yang Shen, and Caiyun Nan
- Subjects
Kerr effect ,Materials science ,Nuclear magnetic resonance ,Condensed matter physics ,Electric field ,Magnetoelectric effect ,General Physics and Astronomy ,Multiferroics ,Biasing ,Coercivity ,Ferroelectricity ,Voltage - Abstract
Switchable voltage modulation of the magnetic properties is reported in different multiferroic bilayers with magnetic films grown on pre-poled ferroelectric substrates, based on the magneto-optical Kerr effect observations. The dynamic voltage control of the magnetic coercive field (Hc) is dependent not only on the materials properties of each ferroic layer, but also on the bias voltage history. The Hc versus electric field behaviors essentially track the dependence of the piezostrains of the substrates on the bias voltage. The observations demonstrate that Hc in such multiferroic bilayers can be controlled by voltage via strain-mediated magnetoelectric coupling and that the Hc change is not an artifact due to a heating effect.
- Published
- 2011
- Full Text
- View/download PDF
46. A magnetoelectric memory cell with coercivity state as writing data bit
- Author
-
Li Zheng, Yuanhua Lin, Jing Wang, and Caiyun Nan
- Subjects
Physics ,Magnetization ,Nuclear magnetic resonance ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Magnetoresistance ,Modulation ,Memory cell ,Electric field ,Multiferroics ,Coercivity ,Ferroelectricity - Abstract
Commercial magnetic recording media employ magnetic-field-induced two different magnetization states ±M to write data. In this paper, we present a magnetic memory cell in which electric-field-induced two different coercive-field Hc states (i.e., low-Hc and high-Hc) rather than ±M are served as writing data bits. A multiferroic magnetoelectric bilayer with Fe0.93Ge0.07 film grown on fully poled ferroelectric BiScO3-PbTiO3 substrate, exhibiting a large electric-field modulation of Hc, is used for illustration of such a prototype electric-write/magnetic-read memory cell which is nonvolatile. The reading process of the different coercive-field Hc information written by electric fields is demonstrated by using magnetoresistance read head.
- Published
- 2010
- Full Text
- View/download PDF
47. Electric-field modulation of magnetic properties of Fe films directly grown on BiScO3–PbTiO3 ceramics
- Author
-
Jing Ma, Jing Wang, Zhangben Wu, Yuanhua Lin, Xiaohui Wang, He Jiang, Jia Mian Hu, Han Wang, and Caiyun Nan
- Subjects
Kerr effect ,Materials science ,Ferromagnetism ,Condensed matter physics ,Electric field ,visual_art ,Composite number ,Magnetoelectric effect ,visual_art.visual_art_medium ,General Physics and Astronomy ,Ceramic ,Coercivity ,Piezoelectricity - Abstract
An electric-field modulation of the magnetic properties through converse magnetoelectric effect was reported in Fe films directly grown on BiScO3–PbTiO3 (BSPT) ceramics based on the magneto-optical Kerr effect. When an electric field was applied on the piezoelectric BSPT ceramics, the coercive field (Hc) of the ferromagnetic Fe films changed dramatically and an upto 60% change in Hc was observed. The Hc electric field curve essentially tracked the dependence of the piezostrain of the BSPT ceramics on the electric field, which definitely demonstrated the magnetic-mechanical-electric coupling in such film-on-substrate composite structures.
- Published
- 2010
- Full Text
- View/download PDF
48. Magnetoelectric coupling in BaTiO3/(NiFe2O4/BaTiO3)n (n=1,2,3,4) multilayered thin films
- Author
-
Jing Liu, Yuanhua Lin, Yi Zhang, and Caiyun Nan
- Subjects
Nuclear magnetic resonance ,Materials science ,Ferromagnetism ,Condensed matter physics ,Ferrimagnetism ,General Physics and Astronomy ,Coupling (piping) ,Heterojunction ,Thin film ,Epitaxy ,Ferroelectricity ,Pulsed laser deposition - Abstract
Multilayered heterostructures, BaTiO3/(NiFe2O4/BaTiO3)n (n=1,2,3,4), with alternating ferroelectric BaTiO3 and ferrimagnetic NiFe2O4 layers were epitaxially grown on (001)-SrTiO3 substrates via pulsed laser deposition technique. The multilayered heterostructures with a total thickness of about 120 nm preserved ferromagnetic and ferroelectric properties at room temperature, strongly depending on the number n due to interface and thickness size effect. The influence of the interface on the magnetoelectric coupling effect in the multilayered thin films were further confirmed by observed increasing magnetoelectric coefficients with the number n.
- Published
- 2009
- Full Text
- View/download PDF
49. Durable Carbon-Coated Li2S Core-Shell Spheres for High Performance Lithium/Sulfur Cells.
- Author
-
Caiyun Nan, Zhan Lin, Honggang Liao, Min-Kyu Song, Yadong Li, and Cairns, Elton J.
- Subjects
- *
LITHIUM sulfur batteries , *CARBON , *CATHODES , *DENDRITIC crystals , *SURFACE coatings , *POLYSULFIDES , *SOLUBILITY , *PARTICLE size determination - Abstract
Lithium sulfide (Li2S) is an attractive cathode material with a high theoretical specific capacity (1166 mAh g-1). However, the poor cycle life and rate capability have remained significant challenges, preventing its practical application. Here, Li2S spheres with size control have been synthesized for the first time, and a CVD method for converting them into stable carbon-coated Li2S core-shell (Li2S@C) particles has been successfully employed. These Li2S@C particles with protective and conductive carbon shells show promising specific capacities and cycling performance with a high initial discharge capacity of 972 mAh g-1 Li2S (1394 mAh g-1 S) at the 0.2C rate. Even with no added carbon, a very high Li2S content (88 wt % Li2S) electrode composed of 98 wt % 1 μm Li2S@C spheres and 2 wt % binder shows rather stable cycling performance, and little morphology change after 400 cycles at the 0.5C rate. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
50. From Single-Component Nanowires to Composite Nanotubes.
- Author
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Yina Zhu, Wei Chen, Caiyun Nan, Qing Peng, Ruji Wang, and Yadong Li
- Published
- 2011
- Full Text
- View/download PDF
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