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排序方式: 共有997条查询结果,搜索用时 537 毫秒
991.
Dr. Dongdong Wang Huili Peng Shaojie Zhang Hongxia Liu Nana Wang Prof. Jian Yang 《Angewandte Chemie (International ed. in English)》2023,62(50):e202315834
Aqueous zinc metal batteries hold great promise for large-scale energy storage because of their high safety, rich material resources and low cost. However, the freeze of aqueous electrolytes hinders low-temperature operation of the batteries. Here, aqueous localized anion-cation aggregated electrolytes composed of Zn(BF4)2 as the salt and tetrahydrofuran (THF) as the diluent, are developed to improve the low-temperature performance of the Zn anode. THF promotes the inclusion of BF4− in the solvation sheath of Zn2+, facilitating the formation of ZnF2-rich solid-electrolyte-interphase. THF also affects the hydrogen bonding between neighboring H2O molecules, effectively lowering the freezing point. Therefore, the full cells of Zn||polyaniline (PANI) exhibit an ultralong cycle life of 8000 cycles with an average Coulombic efficiency of 99.99 % at −40 °C. Impressively, the pouch cells display a high capacity retention of 86.2 % after 500 cycles at −40 °C, which demonstrates the great prospect of such electrolytes in cold regions. This work provides new insights for the design of low-temperature aqueous electrolytes. 相似文献
992.
Dr. Zhuo Zhu Dr. Yinxiang Zeng Zhihao Pei Dr. Deyan Luan Prof. Xin Wang Prof. Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2023,62(31):e202305828
Lithium-sulfur (Li−S) batteries are considered as promising candidates for next-generation energy storage systems in view of the high theoretical energy density and low cost of sulfur resources. The suppression of polysulfide diffusion and promotion of redox kinetics are the main challenges for Li−S batteries. Herein, we design and prepare a novel type of ZnCo-based bimetallic metal–organic framework nanoboxes (ZnCo-MOF NBs) to serve as a functional sulfur host for Li−S batteries. The hollow architecture of ZnCo-MOF NBs can ensure fast charge transfer, improved sulfur utilization, and effective confinement of lithium polysulfides (LiPSs). The atomically dispersed Co−O4 sites in ZnCo-MOF NBs can firmly capture LiPSs and electrocatalytically accelerate their conversion kinetics. Benefiting from the multiple structural advantages, the ZnCo-MOF/S cathode shows high reversible capacity, impressive rate capability, and prolonged cycling performance for 300 cycles. 相似文献
993.
Dr. Zhonglin Liu Lucas J. Oxtoby Juntao Sun Zi-Qi Li Dr. Nana Kim Dr. Geraint H. M. Davies Prof. Keary M. Engle 《Angewandte Chemie (International ed. in English)》2023,62(4):e202214153
The site-selective palladium-catalyzed three-component coupling of unactivated alkenyl carbonyl compounds, aryl- or alkenylboronic acids, and N-fluorobenzenesulfonimide is described herein. Tuning of the steric environment on the bidentate directing auxiliary enhances regioselectivity and facilitates challenging C(sp3)−F reductive elimination from a PdIV intermediate to afford 1,2-carbofluorination products in moderate to good yields. 相似文献
994.
Xiling Wang Xiaodan Lin Yiping Jiang Xiangquan Qin Nana Ma Fuquan Yao Sheng Dong Chuanfei Liu Yingang Feng Longyi Jin Mo Xian Zhiqi Cong 《Angewandte Chemie (International ed. in English)》2023,62(13):e202217678
Applications of the peroxidase activity of cytochrome P450 enzymes in synthetic chemistry remain largely unexplored. We present herein a protein engineering strategy to increase cytochrome P450BM3 peroxidase activity for the direct nitration of aromatic compounds and terminal aryl-substituted olefins in the presence of a dual-functional small molecule (DFSM). Site-directed mutations of key active-site residues allowed the efficient regulation of steric effects to limit substrate access and, thus, a significant decrease in monooxygenation activity and increase in peroxidase activity. Nitration of several phenol and aniline compounds also yielded ortho- and para-nitration products with moderate-to-high total turnover numbers. Besides direct aromatic nitration by P450 variants using nitrite as a nitrating agent, we also demonstrated the use of the DFSM-facilitated P450 peroxidase system for the nitration of the vinyl group of styrene and its derivatives. 相似文献
995.
Dr. Fu-Li Wang Dr. Lin Liu Dr. Chang-Jiang Yang Cheng Luan Dr. Jing Yang Dr. Ji-Jun Chen Dr. Qiang-Shuai Gu Dr. Zhong-Liang Li Prof. Dr. Xin-Yuan Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202214709
The copper-catalyzed enantioconvergent radical C(sp3)−C(sp2) cross-coupling of tertiary α-bromo-β-lactams with organoboronate esters could provide the synthetically valuable α-quaternary β-lactams. The challenge arises mainly from the construction of sterically congested quaternary stereocenters between the tertiary alkyl radicals and chiral copper(II) species. Herein, we describe our success in achieving such transformations through the utilization of a copper/hemilabile N,N,N-ligand catalyst to forge the sterically congested chiral C(sp3)−C(sp2) bond via a single-electron reduction/transmetalation/bond formation catalytic cycle. The synthetic potential of this approach is shown in the straightforward conversion of the corresponding products into many valuable building blocks. We hope that the developed catalytic cycle would open up new vistas for more enantioconvergent cross-coupling reactions. 相似文献
996.
Chenglong Luan Johanna Angona Arjun Bala Krishnan Manuel Corva Pouya Hosseini Markus Heidelmann Ulrich Hagemann Emmanuel Batsa Tetteh Wolfgang Schuhmann Kristina Tschulik Tong Li 《Angewandte Chemie (International ed. in English)》2023,62(28):e202305982
The role of β-CoOOH crystallographic orientations in catalytic activity for the oxygen evolution reaction (OER) remains elusive. We combine correlative electron backscatter diffraction/scanning electrochemical cell microscopy with X-ray photoelectron spectroscopy, transmission electron microscopy, and atom probe tomography to establish the structure–activity relationships of various faceted β-CoOOH formed on a Co microelectrode under OER conditions. We reveal that ≈6 nm β-CoOOH(01 0), grown on [ 0]-oriented Co, exhibits higher OER activity than ≈3 nm β-CoOOH(10 3) or ≈6 nm β-CoOOH(0006) formed on [02 - and [0001]-oriented Co, respectively. This arises from higher amounts of incorporated hydroxyl ions and more easily reducible CoIII−O sites present in β-CoOOH(01 0) than those in the latter two oxyhydroxide facets. Our correlative multimodal approach shows great promise in linking local activity with atomic-scale details of structure, thickness and composition of active species, which opens opportunities to design pre-catalysts with preferred defects that promote the formation of the most active OER species. 相似文献
997.
In engineering practice, one of the important problems is the problem of finding full-strength contours which permits to control stress concentration at the hole boundary. The article addresses the mixed problem of plane elasticity theory for doubly-connected domain with partially unknown boundary conditions. In the presented work the stress state of the given body and full-strength contours were defined. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献