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51.
Wenqing Wang Dr. Kun Rui Kaili Wu Yisha Wang Longwei Ke Xin Wang Feng Xu Prof. Yan Lu Prof. Jixin Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(40):e202200789
Realizing the synergy between active site regulation and rational structural engineering is essential in the electrocatalysis community but still challenging. Here, a matrix-confined co-pyrolysis strategy based on molecular bridging is demonstrated to realize highly dispersed Fe atoms on stereoassembled carbon framework. Both polyacrylonitrile matrix and organic linker from metal–organic frameworks (MOFs) provide sufficient N-anchoring sites for the generation of Fe−N4 moieties. A high Fe loading of 2.9 wt.% is readily achieved based on the scalable approach without post-treatment. Owing to the presence of highly exposed Fe−N−C sites and well-tuned pore structures, isolated Fe atoms on porous carbon nanofiber framework (Fe−SA/NCF) exhibits decent oxygen reduction activity and stability in alkaline conditions via a near four-electron path, demonstrating superior performance as air cathode for zinc-air batteries (ZABs) to commercial Pt/C catalyst. 相似文献
52.
Jiaqi Ke Yufei Zhang Yibo Zhang Minghui Ye Zicheng Zhang Yongchao Tang Xiaoqing Liu Prof. Cheng Chao Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(54):e202201687
Rechargeable zinc-ion batteries (ZIBs) are potential for grid-scale applications owing to their safety, low price, and available sources. The development of ZIBs cathode with high specific capacity, wide operating voltage window and stable cyclability is urgently needed in next-generation commercial batteries. Herein, we report a structurally crystalline-stable Mn(VO3)2 nanobelts cathode for ZIBs prepared via a facile hydrothermal method. The as-synthesized Mn(VO3)2 exhibited high specific capacity of 350 mAh g−1 at 0.1 A g−1, and maintained a capacity retention of 92 % after 10,000 cycles at 2 A g−1. It also showed good rate performance and obtained a reversible capacity of up to 200 mAh g−1 after 600 cycles at 0.2 A g−1 under −20 °C. The electrochemical tests suggest that Mn(VO3)2 nanobelts impart fast Zn2+ ions migration, and the introduction of manganese atoms help make the structures more indestructible, leading to a good rate performance and prolonged cycle lifespan. 相似文献
53.
Lithium (Li)-based batteries are the dominant energy source for consumer electronics, grid storage, and electrified transportation. However, the development of batteries based on graphite anodes is hindered by their limited energy density. With its ultrahigh theoretical capacity (3860 mAh∙g−1), low redox potential (−3.04 V), and satisfactorily low density (0.54 g∙cm−3), Li metal is the most promising anode for next-generation high-energy-density batteries. Unfortunately, the limited cycling life and safety issues raised by dendrite growth, unstable solid electrolyte interphase, and "dead Li" have inhibited their practical use. An effective strategy is to develop a suitable lithiophilic matrix for regulating initial Li nucleation behavior and controlling subsequent Li growth. Herein, single-atom cobalt coordinated to oxygen sites on graphene (Co-O-G SA) is demonstrated as a Li plating substrate to efficiently regulate Li metal nucleation and growth. Owing to its dense and more uniform lithiophilic sites than single-atom cobalt coordinated to nitrogen sites on graphene (Co-N-G SA), high electronic conductivity, and high specific surface area (519 m2∙g−1), Co-O-G SA could significantly reduce the local current density and promote the reversibility of Li plating and stripping. As a result, the Co-O-G SA based Li anodes exhibited a high Coulombic efficiency of 99.9% at a current density of 1 mA∙cm−2 with a capacity of 1 mAh∙cm−2, and excellent rate capability (high current density of 8 mA∙cm−2). Even at a high plating capacity of 6 mAh∙cm−2, the Co-O-G SA electrode could stably cycle for an ultralong lifespan of 1300 h. In the symmetric battery, the Co-O-G SA based Li anode (Co-O-G SA/Li) possessed a stable voltage profile of 18 mV for 780 h at 1 mA∙cm−2, and even at a high current density of 3 mA∙cm−2, its overpotential maintained a small hysteresis of approximately 24 mV for > 550 h. Density functional theory calculations showed that the surface of Co-O-G SA had a stronger interaction with Li atoms with a larger binding energy, −3.1 eV, than that of Co-N-G SA (−2.5 eV), leading to a uniform distribution of metallic Li on the Co-O-G SA surface. More importantly, when matched with a sulfur cathode, the resulting Co-O-G SA/lithium sulfur full batteries exhibited a high capacity of 1002 mAh∙g−1, improved kinetics with a small polarization of 191 mV, and an ultralow capacity decay rate of 0.036% per cycle for 1000 cycles at 0.5C (1C = 1675 mA∙g−1) with a steady Coulombic efficiency of nearly 100%. Therefore, this work provides novel insights into the coordination environment of single atoms for the chemistry of Li metal anodes for high-energy-density batteries. 相似文献
54.
Jinting Zhou Wei Lu Fangyu Hu Mengyu Zhang Liming Jiang Zhiquan Shen 《Journal of polymer science. Part A, Polymer chemistry》2014,52(16):2248-2257
A novel AB type of clickable monomer, (S)‐2‐[(2‐azido‐1‐phenylethylimino)methyl]‐5‐propargyloxyphenol (AMPP) was designed and polymerized to yield a class of main‐chain chiral poly(imine‐triazole)s through the metal‐free click reaction. With the thermally induced polymerization, the desired polytriazoles can be easily prepared in high yields by a stepwise heating‐up process and have the number‐average molecular masses ranging from 5.1 × 103 to 58.1 × 103 (polydispersity indices = 1.38?1.68). The polymers were characterized by Fourier Transform Infrared spectroscopy (FTIR), 1H Nuclear Magnetic Resonance (NMR), and gel permeation chromatography, and their optical properties were studied by fluorescence and circular dichroism (CD) spectroscopies. As a chemosensor, these polymers exhibited a selective “turn‐on” fluorescence enhancement response toward Zn2+ ion over other cations such as Na+, K+, Mg2+, Ca2+, Ag+, Pb2+, Cd2+, Hg2+, Mn2+, and Ni2+ in dimethyl sulfoxide. However, the Zn2+‐induced fluorescence signal was subject to serious interference by Al3+, Cu2+, Cr3+, and Fe3+ ions. Interestingly, the chiral polymer showed distinctive changes in the CD spectra on complexation with Zn2+, which allowed for the discrimination of this ion in the presence of other species tested including those interfering ions observed in the fluorescent detection. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2248–2257 相似文献
55.
Sulfonated polyimide (SPI) and ZrO2 are blended to prepare a series of novel SPI/ZrO2 composite membranes for vanadium redox flow battery (VRFB) application. Results of atomic force microscopy and X‐ray diffraction reveal that ZrO2 is successfully composited with SPI. All SPI/ZrO2 membranes possess high proton conductivity (2.96–3.72 × 10?2 S cm?1) and low VO2+ permeability (2.18–4.04 × 10?7 cm2 min?1). SPI/ZrO2‐15% membrane is determined as the optimum one on account of its higher proton selectivity and improved chemical stability. The VRFB with SPI/ZrO2‐15% membrane presents higher coulombic efficiency and energy efficiency than that with Nafion 117 membrane at the current density, which ranged from 20 to 80 mA cm?2. Cycling tests indicate that the SPI/ZrO2‐15% membrane has good operation stability in the VRFB system. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
56.
57.
Mikhail Kamencev Nina Yakimova Leonid Moskvin Irina Kuchumova Kirill Tkach Yulia Malinina Oleg Tungusov 《Electrophoresis》2015,36(24):3014-3017
Separation of 6Li and 7Li isotopes by CZE was demonstrated. The BGE contained 5 mM 4‐aminopyridine, 0.9 mM oxalic acid, 0.25 mM CTAB, and 0.25% w/v Tween 20 (рН = 9.2). The running conditions were +25 kV at 30°C with indirect photometric detection at 261 nm. Under optimal experimental conditions, the analysis time was less than 21 min. Separation of Li preparations with mole fraction of 6Li ranging from 3.44 up to 90.38% was demonstrated. 相似文献
58.
Dr. Malin Li Dr. Yu Gao Dr. Nan Chen Dr. Xing Meng Prof. Chunzhong Wang Dr. Yaoqing Zhang Dr. Dong Zhang Prof. Yingjin Wei Dr. Fei Du Prof. Gang Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(32):11405-11412
Cu3V2O8 nanoparticles with particle sizes of 40–50 nm have been prepared by the co‐precipitation method. The Cu3V2O8 electrode delivers a discharge capacity of 462 mA h g?1 for the first 10 cycles and then the specific capacity, surprisingly, increases to 773 mA h g?1 after 50 cycles, possibly as a result of extra lithium interfacial storage through the reversible formation/decomposition of a solid electrolyte interface (SEI) film. In addition, the electrode shows good rate capability with discharge capacities of 218 mA h g?1 under current densities of 1000 mA g?1. Moreover, the lithium storage mechanism for Cu3V2O8 nanoparticles is explained on the basis of ex situ X‐ray diffraction data and high‐resolution transmission electron microscopy analyses at different charge/discharge depths. It was evidenced that Cu3V2O8 decomposes into copper metal and Li3VO4 on being initially discharged to 0.01 V, and the Li3VO4 is then likely to act as the host for lithium ions in subsequent cycles by means of the intercalation mechanism. Such an “in situ” compositing phenomenon during the electrochemical processes is novel and provides a very useful insight into the design of new anode materials for application in lithium‐ion batteries. 相似文献
59.
60.
Prediction of 195Pt NMR chemical shifts of dissolution products of H2[Pt(OH)6] in nitric acid solutions by DFT methods: how important are the counter‐ion effects? 下载免费PDF全文
Athanassios C. Tsipis Ioannis N. Karapetsas 《Magnetic resonance in chemistry : MRC》2016,54(8):656-664
195Pt NMR chemical shifts of octahedral Pt(IV) complexes with general formula [Pt(NO3)n(OH)6 ? n]2?, [Pt(NO3)n(OH2)6 ? n]4 ? n (n = 1–6), and [Pt(NO3)6 ? n ? m(OH)m(OH2)n]?2 + n ? m formed by dissolution of platinic acid, H2[Pt(OH)6], in aqueous nitric acid solutions are calculated employing density functional theory methods. Particularly, the gauge‐including atomic orbitals (GIAO)‐PBE0/segmented all‐electron relativistically contracted–zeroth‐order regular approximation (SARC–ZORA)(Pt) ∪ 6–31G(d,p)(E)/Polarizable Continuum Model computational protocol performs the best. Excellent second‐order polynomial plots of δcalcd(195Pt) versus δexptl(195Pt) chemical shifts and δcalcd(195Pt) versus the natural atomic charge QPt are obtained. Despite of neglecting relativistic and spin orbit effects the good agreement of the calculated δ 195Pt chemical shifts with experimental values is probably because of the fact that the contribution of relativistic and spin orbit effects to computed σiso 195Pt magnetic shielding of Pt(IV) coordination compounds is effectively cancelled in the computed δ 195Pt chemical shifts, because the relativistic corrections are expected to be similar in the complexes and the proper reference standard used. To probe the counter‐ion effects on the 195Pt NMR chemical shifts of the anionic [Pt(NO3)n(OH)6 ? n]2? and cationic [Pt(NO3)n(OH2)6 ? n]4 ? n (n = 0–3) complexes we calculated the 195Pt NMR chemical shifts of the neutral (PyH)2[Pt(NO3)n(OH)6 ? n] (n = 1–6; PyH = pyridinium cation, C5H5NH+) and [Pt(NO3)n(H2O)6 ? n](NO3)4 ? n (n = 0–3) complexes. Counter‐anion effects are very important for the accurate prediction of the 195Pt NMR chemical shifts of the cationic [Pt(NO3)n(OH2)6 ? n]4 ? n complexes, while counter‐cation effects are less important for the anionic [Pt(NO3)n(OH)6 ? n]2? complexes. The simple computational protocol is easily implemented even by synthetic chemists in platinum coordination chemistry that dispose limited software availability, or locally existing routines and knowhow. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献