排序方式: 共有158条查询结果,搜索用时 15 毫秒
1.
Changda Wang Shuangming Chen Hui Xie Shiqiang Wei Chuanqiang Wu Li Song 《Liver Transplantation》2019,9(4)
Ion intercalation is an important way to improve the energy storage performance of 2D materials. The dynamic energy storage process in such layered intercalations is important but still a challenge mainly due to the lack of effective operando methods. Herein, a unique atomic Sn4+–decorated vanadium carbide (V2C) MXene not only exhibiting highly enhanced lithium‐ion battery (LIB) performance, but also possessing outstanding rate and cyclic stability because of the expanded interlayer space and the formation of V? O? Sn bonding is demonstrated. In combination with ex situ tests, an operando X‐ray absorption fine structure measurement is developed to explore the dynamic mechanism of V2C@Sn MXene electrodes in LIBs. The results clearly reveal the valence changes of vanadium (V), tin (Sn), and positive contribution of oxygen (O) atoms during the charging/discharging process, confirming their contribution for lithium storage capacity. The stability of intercalated MXene electrode is further in situ studied to prove the key role of V? O? Sn bonding. 相似文献
2.
The oxygen evolution reaction (OER) has aroused extensive interest from materials scientists in the past decade by virtue of its great significance in the energy storage/conversion systems such as water splitting, rechargeable metal–air batteries, carbon dioxide (CO2) reduction, and fuel cells. Among all the materials capable of catalyzing OER, layered double hydroxides (LDHs) stand out as one of the most effective electrocatalysts owing to their compositional and structural flexibility as well as the tenability and the simplicity of their preparation process. For this reason, numerous efforts have been dedicated to adjusting the structure, forming the well‐defined morphology, and developing the preparation methods of LDHs to promote their electrocatalytic performance. In this article, recent advances in the rational design of LDH‐based electrocatalysts toward OER are summarized. Specifically, various tactics for the synthetic methods, as well as structural and composition regulations of LDHs, are further highlighted, followed by a discussion on the influential factors for OER performance. Finally, the remaining challenges to investigate and improve the catalyzing ability of LDH electrocatalysts are stated to indicate possible future development of LDHs. 相似文献
3.
Ziliang Chen Yuan Ha Huaxian Jia Xiaoxiao Yan Mao Chen Miao Liu Renbing Wu 《Liver Transplantation》2019,9(19)
Construction of well‐defined metal–organic framework precursor is vital to derive highly efficient transition metal–carbon‐based electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in water splitting. Herein, a novel strategy involving an in situ transformation of ultrathin cobalt layered double hydroxide into 2D cobalt zeolitic imidazolate framework (ZIF‐67) nanosheets grafted with 3D ZIF‐67 polyhedra supported on the surface of carbon cloth (2D/3D ZIF‐67@CC) precursor is proposed. After a low‐temperature pyrolysis, this precursor can be further converted into hybrid composites composed of ultrafine cobalt nanoparticles embedded within 2D N‐doped carbon nanosheets and 3D N‐doped hollow carbon polyhedra (Co@N‐CS/N‐HCP@CC). Experimental and density functional theory calculations results indicate that such composites have the advantages of a large number of accessible active sites, accelerated charge/mass transfer ability, the synergistic effect of components as well as an optimal water adsorption energy change. As a result, the obtained Co@N‐CS/N‐HCP@CC catalyst requires overpotentials of only 66 and 248 mV to reach a current density of 10 mA cm?2 for HER and OER in 1.0 m KOH, respectively. Remarkably, it enables an alkali‐electrolyzer with a current density of 10 mA cm?2 at a low cell voltage of 1.545 V, superior to that of the IrO2@CC||Pt/C@CC couple (1.592 V). 相似文献
4.
Xing Xu Hua Huo Jiyuan Jian Liguang Wang He Zhu Sheng Xu Xiaoshu He Geping Yin Chunyu Du Xueliang Sun 《Liver Transplantation》2019,9(15)
Ni‐rich Li[NixCoyMn1?x?y]O2 (x ≥ 0.8) layered oxides are the most promising cathode materials for lithium‐ion batteries due to their high reversible capacity of over 200 mAh g?1. Unfortunately, the anisotropic properties associated with the α‐NaFeO2 structured crystal grains result in poor rate capability and insufficient cycle life. To address these issues, a micrometer‐sized Ni‐rich LiNi0.8Co0.1Mn0.1O2 secondary cathode material consisting of radially aligned single‐crystal primary particles is proposed and synthesized. Concomitant with this unique crystallographic texture, all the exposed surfaces are active {010} facets, and 3D Li+ ion diffusion channels penetrate straightforwardly from surface to center, remarkably improving the Li+ diffusion coefficient. Moreover, coordinated charge–discharge volume change upon cycling is achieved by the consistent crystal orientation, significantly alleviating the volume‐change‐induced intergrain stress. Accordingly, this material delivers superior reversible capacity (203.4 mAh g?1 at 3.0–4.3 V) and rate capability (152.7 mAh g?1 at a current density of 1000 mA g?1). Further, this structure demonstrates excellent cycling stability without any degradation after 300 cycles. The anisotropic morphology modulation provides a simple, efficient, and scalable way to boost the performance and applicability of Ni‐rich layered oxide cathode materials. 相似文献
5.
Dongwei Li Kang Liang Wenlong Cheng Changming Li Dongyuan Zhao Biao Kong 《Liver Transplantation》2019,9(21)
Freestanding layered membrane–based devices have broad applications in highly efficient energy‐storage/conversion systems. The liquid–solid interface is considered as a unique yet versatile interface for constructing such layered membrane–based devices. In this review, the authors outline recent developments in the fabrication of soft materials to functionalize layered devices from the aspect of liquid–solid interfacial assembly and engineering arts. Seven liquid–solid interfacial assembly strategies, including flow‐directed, superlattice, solvent‐casting, evaporation‐induced, dip‐coating, spinning, and electrospinning assemblies, are comprehensively highlighted with a focus on their synthetic pathways, formation mechanisms, and interface engineering strategies. Meanwhile, recent representative works on layered membrane–based devices for electrochemical energy applications are presented. Finally, challenges and opportunities of this research area are highlighted in order to stimulate future developments. This review not only offers comprehensive and practical approaches to assemble liquid–solid interfaces with soft materials for various important layered electrochemical energy devices but also sheds lights on fundamental insights by thoughtful discussions on performance enhancement mechanisms of these electrochemical energy systems. 相似文献
6.
Three silhouette traps of novel design were used to investigate the trap finding ability of female Austrosimulium bancrofti (Taylor) (Diptera: Simuliidae) in southeast Queensland. The traps were 'upright', 'elongate' or 'square' in shape. Five highly significant factors: hour after sunrise, temperature, relative humidity, trap shape and distance between traps, were included in a model which generated fitted estimates of flies captured under defined conditions. The rate of increase and the level of maximum capture rate indicated that the elongate trap captured the highest numbers of blackflies. An interaction between hour after sunrise and temperature suggests a strong endogenous modification of trap finding activity. Numbers captured increased with increasing distance between traps and decreasing relative humidity. The importance of these results in understanding behaviour of A. bancrofti is discussed. 相似文献
7.
Xun Guo Guozhao Fang Wenyu Zhang Jiang Zhou Lutong Shan Liangbing Wang Chao Wang Tianquan Lin Yan Tang Shuquan Liang 《Liver Transplantation》2018,8(27)
Rechargeable aqueous zinc‐ion batteries (ZIBs) with high safety and low‐cost are highly desirable for grid‐scale energy storage, yet the energy storage mechanisms in the current cathode materials are still complicated and unclear. Hence, several sodium vanadates with NaV3O8‐type layered structure (e.g., Na5V12O32 and HNaV6O16·4H2O) and β‐Na0.33V2O5‐type tunneled structure (e.g., Na0.76V6O15) are constructed and the storage/release behaviors of Zn2+ ions are deeply investigated in these two typical structures. It should be mentioned that the 2D layered Na5V12O32 and HNaV6O16·4H2O with more effective path for Zn2+ diffusion exhibit higher ion diffusion coefficients than that of tunneled Na0.76V6O15. As a result, Na5V12O32 delivers higher capacity than that of Na0.76V6O15, and a long‐term cyclic performance up to 2000 cycles at 4.0 A g?1 in spite of its capacity fading. This work provides a new perspective of Zn2+ storage mechanism in aqueous ZIB systems. 相似文献
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9.
Wontae Lee Shoaib Muhammad Taewhan Kim Hyunchul Kim Eunkang Lee Mihee Jeong Suhan Son Jae‐Hyun Ryou Won‐Sub Yoon 《Liver Transplantation》2018,8(4)
An increase in the amount of nickel in LiMO2 (M = Ni, Co, Mn) layered system is actively pursued in lithium‐ion batteries to achieve higher capacity. Nevertheless, fundamental effects of Ni element in the three‐component layered system are not systematically studied. Therefore, to unravel the role of Ni as a major contributor to the structural and electrochemical properties of Ni‐rich materials, Co‐fixed LiNi0.5+xCo0.2Mn0.3–xO2 (x = 0, 0.1, and 0.2) layered materials are investigated. The results, on the basis of synchrotron‐based characterization techniques, present a decreasing trend of Ni2+ content in Li layer with increasing total Ni contents. Moreover, it is discovered that the chex.‐lattice parameter of layered system is not in close connection with the interslab thickness related to actual Li ion pathway. The interslab thickness increases with increasing Ni concentration even though the chex.‐lattice parameter decreases. Furthermore, the lithium ion pathway is preserved in spite of the fact that the c‐axis is collapsed at highly deintercalated states. Also, a higher Ni content material shows better structural properties such as larger interslab thickness, lower cation disorder, and smoother phase transition, resulting in better electrochemical properties including higher Li diffusivity and lower overpotential when comparing materials with lower Ni content. 相似文献
10.
We have studied the fluorescence of Mg-Al-Eu ternary layered hydroxides (TLH) quenched by tryptophan (Trp). IR spectroscopy was used to evaluate the change of Trp structure which was caused by TLH. XRD and TG-DTA results further suggested a structural change of Trp after being reacted with TLH. XPS characterization confirmed a strong chemical reaction between Trp and TLH. These studies may present more direct evidence to explain the interrelation between the structural change of Trp and the fluorescent quenching of TLH. 相似文献