Hierarchical mesoporous perovskite nanowires for ultrahigh-capacity Li-air battery Li-ion batteries have developed rapidly in recent years because of their low cost, long cycle life, good reversibility and no memory effect. However, the highest energy storage of Li-ion batteries is insufficient to satisfy the ever-increasing requirements for batteries with high capacities. Recently, Li-air batteries have attracted great interest because they potentially have much higher energy storage density compared with all other chemical batteries. They could theoretically offer very high specific energies (i.e. 5000 Whkg −1 ) because of the cathode reaction: 2Li + O 2 → Li 2 O 2 and 2Li + 0.5O 2 → Li 2 O in nonaqueous electrolyte. However, it also brings many problems including the precipitation of reaction products Li 2 O 2 /Li 2 O or electrolyte decomposition products on the catalyst and electrode eventually blocked the oxygen pathway and limited the capacity of the Li-air batteries. To enhance the performance, constructing a structure with continuous oxygen diffusion channels is very important. In WUT-Harvard Joint Nano Key Laboratory ， Liqiang Mai and colleagues synthesized hierarchical mesoporous perovskite structure La 0.5 Sr 0.5 CoO 2.91 (LSCO) nanowires constructed by nanorods using a facile multi-step micro-emulsion followed by a slow annealing method. The high-performance catalysts for the oxygen reduction reaction (ORR) of hierarchical mesoporous LSCO nanowires was demonstrated, with low peak-up potential and high limiting diffusion current, via rotating disk electrode (RDE) measurements in both aqueous electrolytes and nonaqueous electrolytes. Furthermore, Li-air battery based on hierarchical mesoporous LSCO nanowires and nonaqueous electrolyte was fabricated, which exhibits ultrahigh capacity, c.a., over 11000 mAh g –1 , with the improvement of one order of magnitude than LSCO nanoparticles. A large specific surface area with ~ 10 nm size pores was confirmed by BET. HRTEM demonstrated LSCO nanorods are tightly attached to each other at atomic level when they formed the hierarchical nanowire. This structure can provide continuous oxygen diffusion channels that contribute to its electrocatalytic performance. “Constructing hierarchical perovskite LSCO mesoporous nanowires in this paper is a simple and efficient route to provide continuous channels for oxygen transmission and ionic diffusion. The hierarchical perovskite mesoporous LSCO will have great potential applications in Li-air battery, fuel cells or other electrochemical devices.” saysMai. Reference 1. Y. Zhao, L. Xu, L. Mai * , C. Han, Q. An, X. Xu, X. Liu, and Q. Zhang, Hierarchical mesoporous perovskite La 0.5 Sr 0.5 CoO 2.91 nanowires with ultrahigh capacity for Li-air battery. PNAS. (2012). Author affiliation State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China *Email: mlq518@whut.edu.cn
Mai Group Hierarchical heterostructured nanowire electrode study published in Nature Communications Prof Liqiang Mai and co-authors from WUT-Harvard Joint Nano Key Laboratory have published a study in the international leading journal Nature Communications on July 5, 2011 ( Nat. Commun. 2011, 2 : 381 (doi: 10.1038/ncomms1387) )，which was chosen as featured image on the homepage of Nature Communications . As energy storage devices with properties intermediate to those of batteries and electrostatic capacitors, electrochemical supercapacitors exhibit the desirable properties of high power density (ten times more than batteries), fast charging (with seconds), excellent cycling stability, small size and low mass, which make them one of the most promising candidates for next-generation power devices. Currently, most commercial supercapacitors are made of high-surface-area carbonaceous materials. However, these supercapacitors might not provide sufficient energy/power densities or efficiencies, and the specific capacitance severely decreases under high current. In light of such issues of traditional supercapacitors as low capacitance of and poor performance under high current density, Liqiang Mai and co-workers of WUT-Harvard Joint Nano Key Laboratory have now controllably synthesized hierarchical MnMoO 4 /CoMoO 4 heterostructured nanowires using a facile refluxing method under mild conditions and successfully fabricate asymmetric supercapacitors based on hierarchical CoMoO 4 heterostructured nanowires, which show a specific capacitance of 187.1 F g -1 at a current density of 1 A g -1 , and good reversibility with cycling efficiency of 98% after 1,000 cycles. These results further demonstrate that constructing 3D hierarchical heterostructures can improve electrochemical properties. This is due to the fact that the BET surface area increased (The BET surface area of MnMoO 4 is 3.17 m 2 /g, while MnMoO 4 /CoMoO 4 nanowires after hierarchical heterostructured construction can reach to 54.06 m 2 /g)，self-aggregation of the hierarchical MnMoO 4 /CoMoO 4 heterostructured nanowires was greatly reduced，and can provide more surface sites for redox reaction to enable OH - access to the heterostructures facilely. The hierarchical MnMoO 4 /CoMoO 4 nanowire heterostructure will be a unique structure that has potential applications in energy storage and other electrochemical nano-devices. Based on this study, a Chinese invention patent (20110048928.3) has been applied. Mai Group mainly focuses on the research of nanowire energy materials devices. The group have published more than 60 papers tagged by SCI on the leading journal, such as Nature Communications , Nano Letters , Proceedings of the National Academy of Sciences , Advanced Materials , and was invited to write four reviews by Materials Today, Journal of Materials Research etc. Recently published papers have been cited more than 500 times, and were highlighted by some famous news websites such as Nature Asia Materials , Nanowerk . The research got much attention and positive comments by many famous scholars, i.e., Prof M.S. Whittingham and Prof G.D. Stucky. The above research was supported by National Nature Science Foundation of China, Science Technology Ministry of China, and Ministry of Education of China. Nature Communications website: http://www.nature.com/ncomms/index.html The websites of the paper published by Prof Liqiang Mai: http://www.nature.com/ncomms/journal/v2/n7/full/ncomms1387.html Note: Nature, first published on 4 November 1869, is the world's most cited interdisciplinary science journal . As one the Nature series of journals, Nature Communications publish research papers in all areas of the biological, chemical and physical sciences, encouraging papers that provide a multidisciplinary approach. The research will be of the highest quality and will represent advances of significant interest to specialists within each field. This is the first paper published in Nature-branded journal by the researchers of our university. From http://sklwut.whut.edu.cn/en/NewsShow.aspx?NewsId=420
Thiol-Capped ZnO Nanowire/Nanotube Arrays with Tunable Magnetic Properties at Room Temperature Author: Deng, Su-Zi, Fan, Hai-Ming,* Wang, Miao, Zheng, Min-Rui, Yi, Jia-Bao, Wu, Rong-Qin, Tan, Hui-Ru, Sow, Chorng-Haur , Ding, Jun, Feng, Yuan-Ping, Loh, Kian-Ping* ACS NANO Volume: 4 Issue: 1 Pages: 495-505 Abstract: The present study reports room-temperature ferromagnetic behaviors in three-dimensional (3D)-aligned thiol-capped single-crystalline ZnO nanowire (NW) and nanotube (NT) arrays as well as polycrystalline ZnO NT arrays. Besides the observation of height-dependent saturation magnetization, a much higher M-s of 166 mu emu cm(-2) has been found in NTs compared to NWs (36 mu emu cm(-2)) due to larger surface area in ZnO NTs, indicating morphology-dependent magnetic properties in ZnO NW/NT systems. Density functional calculations have revealed that the origin of ferromagnetism is mainly attributed to spin-polarized 3p electrons in S sites and, therefore, has a strong correlation with Zn-S bond anisotropy. The preferential magnetization-direction of both single-crystalline NTs and NWs lies perpendicular to the tube/wire axis due to the aligned high anisotropy orientation of the Zn-S bonds on the lateral (100) face of ZnO NWs and NTs. Polycrystalline ZnO NTs, however, exhibit a preferential magnetization direction parallel to the tube axis which is ascribed to shape anisotropy dominating the magnetic response. Our results demonstrate the interplay of morphology, dimensions, and crystallinity on spin alignment and magnetic anisotropy in a 3D semiconductor nanosystem with interfacial magnetism. 简评： 通过控制ZnO纳米线的尺寸和晶体结构，从而有可能调制界面磁学性质。
Germanium is an effective catalyst for the growth of highly aligned, closely packed polycrystalline Al 2 O 3 and amorphous SiO 2 nanowire bunches. The Ge-catalyzed nanowire growth exhibits interesting growth behavior not observed in conventional Au-catalyzed nanowire growth. Nanoscale , 2009, 1 , 347
It is known that ZnO nanostructures are attractive for its promised application such as energy harvest, room temperature UV laser, and FET devices etc. For these, the requirement for patterned vertical growth ZnO nanowire arrays is urgent. Though high quality vertical ZnO nanowire arrays can be achieved by CVD growth on epitaxial substrates such as sapphire, SiC, GaN, all the reported methods are more complex compared to our new method. As shown in the paper, our growth process requires no carry gases, no catalysts, no expensive substrates, and no complicated and expensive fabricated facilities. Just a simple, inexpensive and robust process for making high quanlity nanowire vertical arrays over large area. Combined with transitional Photo lithography, patterned nan! owire arrays can be easily achieved and the controllable growth of single ZnO nanowire on one site is also demonstrated. We hope our work can accelerate the application research of ZnO nanostructure area. http://pubs.acs.org/doi/abs/10.1021/nn800527m
标签: nanowire
