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Hongxing Jia Prof. Guilin Zhuang Qiang Huang Jinyi Wang Yayu Wu Shengsheng Cui Prof. Shangfeng Yang Prof. Pingwu Du 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(10):2159-2163
Bottom-up synthesis of π-extended macrocyclic carbon rings is promising for constructing length- and diameter-specific carbon nanotubes (CNTs). However, it is still a great challenge to realize size-controllable giant carbon macrocycles. Herein, a tunable synthesis of curved nanographene-based giant π-extended macrocyclic rings (CHBC[n]s; n=8, 6, 4), as finite models of armchair CNTs, is reported. Among them, CHBC[8] contains 336 all-carbon atoms and is the largest cyclic conjugated molecular CNT segment ever reported. CHBC[n]s were systematically characterized by various spectroscopic methods and applied in photoelectrochemical cells for the first time. This revealed that the proton chemical shifts, fluorescence, and electronic and photoelectrical properties of CHBC[n]s are highly dependent on the macrocycle diameter. The tunable bottom-up synthesis of giant macrocyclic rings could pave the way towards large π-extended diameter- and chirality-specific CNT segments. 相似文献
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Dan Xie Huan-Huan Li Yan-Hong Shi Wan-Yue Diao Ru Jiang Prof. Hai-Zhu Sun Prof. Xing-Long Wu Dr. Wenliang Li Dr. Chao-Ying Fan Prof. Jing-Ping Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(4):853-862
The Fe-based transition metal oxides are promising anode candidates for lithium storage considering their high specific capacity, low cost, and environmental compatibility. However, the poor electron/ion conductivity and significant volume stress limit their cycle and rate performances. Furthermore, the phenomena of capacity rise and sudden decay for α-Fe2O3 have appeared in most reports. Here, a uniform micro/nano α-Fe2O3 nanoaggregate conformably enclosed in an ultrathin N-doped carbon network (denoted as M/N-α-Fe2O3@NC) is designed. The M/N porous balls combine the merits of secondary nanoparticles to shorten the Li+ transportation pathways as well as alleviating volume expansion, and primary microballs to stabilize the electrode/electrolyte interface. Furthermore, the ultrathin carbon shell favors fast electron transfer and protects the electrode from electrolyte corrosion. Therefore, the M/N-α-Fe2O3@NC electrode delivers an excellent reversible capacity of 901 mA h g−1 with capacity retention up to 94.0 % after 200 cycles at 0.2 A g−1. Notably, the capacity rise does not happen during cycling. Moreover, the lithium storage mechanism is elucidated by ex situ XRD and HRTEM experiments. It is verified that the reversible phase transformation of α↔γ occurs during the first cycle, whereas only the α-Fe2O3 phase is reversibly transformed during subsequent cycles. This study offers a simple and scalable strategy for the practical application of high-performance Fe2O3 electrodes. 相似文献
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Chen Dan Dan He Zhi Qiang Wang Min Wu Di Chen Xiang Ying Zhang Zhong Jie 《Journal of Solid State Electrochemistry》2020,24(3):641-654
Journal of Solid State Electrochemistry - In the present work, we demonstrate a strategy of combining boron doping and porosity engineering for a highly modulated carbon component and pore... 相似文献