共查询到20条相似文献，搜索用时 15 毫秒
1.
2.
Bu Yuan Guan Akihiro Kushima Le Yu Sa Li Ju Li Xiong Wen Lou 《Advanced materials (Deerfield Beach, Fla.)》2017,29(17)
Metal–organic frameworks (MOFs) or coordination polymers (CPs) have been used as precursors for synthesis of materials. Unlike crystalline MOF, amorphous CP is nonspecific to metal cation species, therefore its composition can be tuned easily. Here, it is shown that amorphous CP can be used as general synthesis precursors of highly complex mixed metal oxide shells. As a proof of concept, Ni? Co coordination polymer spheres are first synthesized and subsequently transformed into seven‐layered Ni? Co oxide onions by rapid thermal oxidation. This approach is very versatile and can be applied to produce ternary and quaternary metal oxide onions with tunable size and composition. The Ni? Co oxide onions exhibit exceptional charge storage capability in aqueous electrolyte with high specific capacitance (≈1900 F g?1 at 2 A g?1), good rate capability, and ultrahigh cycling stability (93.6% retention over 20 000 cycles). A hybrid supercapacitor against graphene/multishelled mesoporous carbon sphere shows a high energy density of 52.6 Wh kg?1 at a power density of 1604 W kg?1 (based on active materials weight), as well as remarkable cycling stability. 相似文献
3.
4.
A noncatalytic and template-free vapor transport process was developed to make possible simultaneous growth of single-crystalline tin nanowires, nanosquares, nanodisks, and polycrystalline nanoparticles. The formation of such a rich variety of morphologies in a single growth experiment can be attributed to variations in the growth rate among different crystallographic planes when employing the vapor-solid growth mechanism. Structural characterization with high-resolution transmission electron microscopy reveals a preferential growth direction of [100] in Sn nanowires, nanosquares, and nanodisks. Shape-dependent superconducting properties are observed. These four types of Sn nanostructures all show typical diamagnetic behavior in magnetization measurements, with the three anisotropically shaped nanostructures (nanowires, nanosquares, and nanodisks) showing one order of magnitude enhancement in the working magnetic field ranges for superconductivity, compared to bulk Sn and Sn nanoparticles. The magnetic field range is broadest for nanowires, followed by nanodisks, nanosquares, and nanoparticles. 相似文献
5.
6.
AbstractMetal ion coordination in discrete or extended metallo-supramolecular assemblies offers ample opportunity to fabricate and study devices and materials that are equally important for fundamental research and new technologies. Metal ions embedded in a specific ligand field offer diverse thermodynamic, kinetic, chemical, physical and structural properties that make these systems promising candidates for active components in functional materials. A key challenge is to improve and develop methodologies for placing these active modules in suitable device architectures, such as thin films or mesophases. This review highlights recent developments in extended, polymeric metallo-supramolecular systems and discrete polyoxometalates with an emphasis on materials science. 相似文献
7.
8.
使用水平石英管式电炉，以二氧化锡和石墨的混合物为原材料、高纯氮气为载气，在850℃温度下用直接热蒸发法制备二氧化锡纳米线．衬底硅片的直径为10mm，其上覆盖一层5nm厚的金催化剂．原材料放在石英舟中，离原材料30mm的下风口处放置硅衬底，原材料和硅衬底都放置在石英管的中部电炉的恒温区内．用扫描电子显微镜（SEM）和透射电子显微镜（TEM）观察到二氧化锡的纳米线结构；X射线衍射（XRD）表明二氧化锡纳米线具有四方金红石结构；选区电子衍射（SAED）照片表明二氧化锡纳米线具有完善的晶体结构．不同生长时间下制备样品的扫描电子显微镜和透射电子显微镜照片再现了二氧化锡纳米线的生长过程，该纳米线的生长符合传统的VLS生长机制． 相似文献
9.
Chuangye Lu Da Zhu Yan Su Hong Xu Cheng Gu 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(18):2207720
Conjugated coordination polymers (CCPs) have attracted extensive attention for various applications related to energy storage and conversion in the past few years, despite that there are many CCPs with unclear chemical states and structures. Here, linear CCPs (LCCPs), with metal–O4 active sites grown on carbon paper (CP) for oxygen evolution reaction (OER), are presented. The LCCPs with high crystallinity and simple structures exhibit the order of electrocatalytic activity of Co–O4 > Ni–O4 > Fe–O4 in terms of the metal–O4 centers. The Co-based LCCP shows higher OER performance (263 mV at 10 mA cm−2) and better durability (90 h at 30 mA cm−2) than commercial IrO2/CP. The structures and chemical states of LCCPs are carefully investigated, and density functional theory is used to reveal the mechanism of OER at the central metal site. This investigation into LCCPs provides new sights for a better understanding of CCPs and expands the applications of LCCPs with metal–O4 sites. 相似文献
10.
Anatoli Serghei Jodie L. Lutkenhaus Daniel F. Miranda Kathleen McEnnis Friedrich Kremer Thomas P. Russell 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(16):1822-1826
Phase transitions of polymeric materials are accompanied by changes in density as a function of temperature. Being able to measure these changes in polymeric systems in one, two or three dimensions on the nanoscopic length‐scale is a challenge, but it would provide a simple route to assess phase transitions in nanoscopically confined systems. It is shown that the measurement of the dielectric permittivity in the high frequency limit (in spectral regions not affected by dielectric dispersions) offers an effective and very sensitive means to assess density fluctuations, and hence phase transitions, in nanoscopic systems. The sensitivity of this approach is demonstrated by assessing the phase transition behavior of ferroelectric polymer nanowires confined within alumina membranes. No significant shifts in the Curie transition are observed down to pore diameters as small as 15 nm. 相似文献
11.
12.
Yao Liu Haifeng Wang Huanli Dong Lang Jiang Wenping Hu Xiaowei Zhan 《Small (Weinheim an der Bergstrasse, Germany)》2013,9(2):294-299
A fluorene‐based donor–acceptor conjugated polymer is synthesized and the polymer nanowires are successfully prepared with high quality and large scale using a simple and practical template dipping method. These amorphous polymer nanowires are flexible and show excellent photoconductive properties with reliable reproducibility. The individual nanowire photoswitches exhibit a responsivity as high as 1700 mA W?1 and an on/off ratio as high as 2000 under a light intensity of 5.76 mW cm?2 and a driving voltage of 40 V. 相似文献
13.
14.
Akiyama G Matsuda R Sato H Takata M Kitagawa S 《Advanced materials (Deerfield Beach, Fla.)》2011,23(29):3294-3297
15.
16.
17.
18.
19.
Poting Liu Alexander Schleusener Gabriel Zieger Arne Bochmann Matthijs A. van Spronsen Vladimir Sivakov 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(12):2206318
Tin-containing layers with different degrees of oxidation are uniformly distributed along the length of silicon nanowires formed by a top-down method by applying metalorganic chemical vapor deposition. The electronic and atomic structure of the obtained layers is investigated by applying nondestructive surface-sensitive X-ray absorption near edge spectroscopy using synchrotron radiation. The results demonstrated, for the first time, a distribution effect of the tin-containing phases in the nanostructured silicon matrix compared to the results obtained for planar structures at the same deposition temperatures. The amount and distribution of tin-containing phases can be effectively varied and controlled by adjusting the geometric parameters (pore diameter and length) of the initial matrix of nanostructured silicon. Due to the occurrence of intense interactions between precursor molecules and decomposition by-products in the nanocapillary, as a consequence of random thermal motion of molecules in the nanocapillary, which leads to additional kinetic energy and formation of reducing agents, resulting in effective reduction of tin-based compounds to a metallic tin state for molecules with the highest penetration depth in the nanostructured silicon matrix. This effect will enable clear control of the phase distributions of functional materials in 3D matrices for a wide range of applications. 相似文献
20.
Stephen Nagaraju Myakala;Hannah Rabl;Jasmin S. Schubert;Samar Batool;Pablo Ayala;Dogukan H. Apaydin;Alexey Cherevan;Dominik Eder; 《Small (Weinheim an der Bergstrasse, Germany)》2024,20(33):2400348
Production of green hydrogen (H2) is a sustainable process able to address the current energy crisis without contributing to long-term greenhouse gas emissions. Many Ag-based catalysts have shown promise for light-driven H2 generation, however, pure Ag—in its bulk or nanostructured forms—suffers from slow electron transfer kinetics and unfavorable Ag─H bond strength. It is demonstrated that the complexation of Ag with various chalcogenides can be used as a tool to optimize these parameters and reach improved photocatalytic performance. In this work, metal-organic-chalcogenolate assemblies (MOCHAs) are introduced as effective catalysts for light-driven hydrogen evolution reaction (HER) and investigate their performance and structural stability by examining a series of AgXPh (X = S, Se, and Te) compounds. Two catalyst-support sensitization strategies are explored: by designing MOCHA/TiO2 composites and by employing a common Ru-based photosensitizer. It is demonstrated that the heterogeneous approach yields stable HER performance but involves a catalyst transformation at the initial stage of the photocatalytic process. In contrast to this, the visible-light-driven MOCHA-dye dyad shows similar HER activity while also ensuring the structural integrity of the MOCHAs. The work shows the potential of MOCHAs in constructing photosystems for catalytic H2 production and provides a direct comparison between known AgXPh compounds. 相似文献