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991.
992.
The lithium metal battery has been considered as a promising candidate for next generation batteries.However,safety concerns caused by uncontrollable lithium dendrite growth on lithium anode are severely hampering the commercial application.Metal-organic frameworks(MOFs)become one of the most attractive materials due to the high porosity,structural designability and tunability.With unique open channels and pores as well as functional components in MOFs,the transportation and deposition of lithium ions can be regulated,which leads to enhanced electrochemical prope rties.Various strategies for lithium metal protection are proposed in recent wo rks on applications of MOFs in lithium metal batteries.In this review,we highlight latest key approaches in this field and discuss the prospects for MOFs in advanced Li anodes. 相似文献
993.
Chitosan (CS) with good hydrophilicity and charged property was used to modify graphene oxide (GO), the obtained GO‐CS was used as a novel modifier to fabricate thin film composite forward osmosis (FO) membranes. The results revealed that the amino groups on CS reacted with carboxyl groups on GO, and the lamellar structure of the GO nanosheets was peeled off by CS, resulting in the reducing of their thicknesses. The GO‐CS improved the hydrophilicity of polyethersulfone (PES) substrate, and their contact angles decreased to 64° with the addition of GO‐CS in the substrate. GO‐CS also increased the porosity of the substrate and surface roughness of FO membrane, thereby optimizing the water flux and reverse salt flux of FO membrane. The average water flux of the FO membrane reached the optimal flux of 21.34 L/(m2 h) when GO‐CS addition was 0.5 wt%, and further addition of GO‐CS to the substrate would decrease the water flux of FO membrane, and the reverse salt flux also decreased to the lowest value of 2.26 g/(m2 h). However, the salt rejection of the membrane increased from 91.4% to 95.1% when GO‐CS addition increased from 0.5 to 1.0 wt% under FO mode using 1 mol/L sodium chloride (NaCl) solution as draw solution (DS). In addition, high osmotic pressure favored water permeation, and at the same concentration of DS, magnesium chloride (MgCl2) exhibited better properties than NaCl. These results all suggested that GO‐CS was a good modifier to fabricate FO membrane, and MgCl2 was a good DS candidate. 相似文献
994.
Dr. Jianyan Lin Xin Du Prof. Dr. Martin Rahm Dr. Hong Yu Prof. Dr. Haiyang Xu Prof. Dr. Guochun Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):9240-9247
Fluorination is a proven method for challenging the limits of chemistry, both structurally and electronically. Here we explore computationally how pressures below 300 GPa affect the fluorination of several transition metals. A plethora of new structural phases are predicted along with the possibility for synthesizing four unobserved compounds: TcF7, CdF3, OsF8, and IrF8. The Ir and Os octaflourides are both predicted to be stable as quasi-molecular phases with an unusual cubic ligand coordination, and both compounds formally correspond to a high oxidation state of +8. Electronic-structure analysis reveals that otherwise unoccupied 6p levels are brought down in energy by the combined effects of pressure and a strong ligand field. The valence expansion of Os and Ir enables ligand-to-metal F 2p→M 6p charge transfer that strengthens M−F bonds and decreases the overall bond polarity. The lower stability of IrF8, and the instability of PtF8 and several other compounds below 300 GPa, is explained by the occupation of M−F antibonding orbitals in octafluorides with a metal-valence-electron count exceeding 8. 相似文献
995.
Min Wang Jia-Qi Wang Cong Xi Chuan-Qi Cheng Cheng-Qin Zou Rui Zhang Ya-Meng Xie Zhong-Lu Guo Prof. Cheng-Chun Tang Dr. Cun-Ku Dong Prof. Yong-Jun Chen Prof. Xi-Wen Du 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(28):11607-11612
Developing highly efficient and low-cost photocatalysts for overall water splitting has long been a pursuit for converting solar power into clean hydrogen energy. Herein, we demonstrate that a nonstoichiometric nickel–cobalt double hydroxide can achieve overall water splitting by itself upon solar light irradiation, avoiding the consumption of noble-metal co-catalysts. We employed an intensive laser to ablate a NiCo alloy target immersed in alkaline solution, and produced so-called L-NiCo nanosheets with a nonstoichiometric composition and O2−/Co3+ ions exposed on the surface. The nonstoichiometric composition broadens the band gap, while O2− and Co3+ ions boost hydrogen and oxygen evolution, respectively. As such, the photocatalyst achieves a H2 evolution rate of 1.7 μmol h−1 under AM 1.5G sunlight irradiation and an apparent quantum yield (AQE) of 1.38 % at 380 nm. 相似文献
996.
Dr. Sampa Maiti Dr. Saikat Manna Nicholas Banahene Lucynda Pham Zhijie Liang Jun Wang Yi Xu Reuben Bettinger John Zientko Prof. Dr. Aaron P. Esser-Kahn Prof. Dr. Wenjun Du 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(43):19105-19109
Efforts to synthesize degradable polymers from renewable resources are deterred by technical and economic challenges; especially, the conversion of natural building blocks into polymerizable monomers is inefficient, requiring multistep synthesis and chromatographic purification. Herein we report a chemoenzymatic process to address these challenges. An enzymatic reaction system was designed that allows for regioselective functional group transformation, efficiently converting glucose into a polymerizable monomer in quantitative yield, thus removing the need for chromatographic purification. With this key success, we further designed a continuous, three-step process, which enabled the synthesis of a sugar polymer, sugar poly(orthoester), directly from glucose in high yield (73 % from glucose). This work may provide a proof-of-concept in developing technically and economically viable approaches to address the many issues associated with current petroleum-based polymers. 相似文献
997.
Bingqing Lin Xi Wu Prof. Dr. Lin Xie Yongqiang Kang Prof. Dr. Hongda Du Prof. Dr. Feiyu Kang Prof. Dr. Jia Li Prof. Dr. Lin Gan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20528-20532
Resolving interstitial hydrogen atoms at the surfaces and interfaces is crucial for understanding the mechanical and physicochemical properties of metal hydrides. Although palladium (Pd) hydrides hold important applications in hydrogen storage and electrocatalysis, the atomic position of interstitial hydrogen at Pd hydride near surfaces still remains undetermined. We report the first direct imaging of subsurface hydrogen atoms absorbed in Pd nanoparticles by using differentiated and integrated differential phase contrast within an aberration-corrected scanning transmission electron microscope. In contrast to the well-established octahedral interstitial sites for hydrogen in the bulk, subsurface hydrogen atoms are directly identified to occupy the tetrahedral interstices. DFT calculations show that the amount and the occupation type of subsurface hydrogen atoms play an indispensable role in fine-tuning the electronic structure and associated chemical reactivity of the Pd surface. 相似文献
998.
Jiaxi Zhang Longhai Zhang Li Du Huolin L. Xin John B. Goodenough Zhiming Cui 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(40):17641-17646
A group of newly reported antiperovskite nitrides CuxIn1−xNNi3 (0≤x≤1) with tunable composition are employed as electrocatalysts for the hydrogen evolution reaction (HER). Cu0.4In0.6NNi3 shows the highest intrinsic performance among all developed catalysts with an overpotential of merely 42 mV at 10 mA cmgeo−2. Stability tests at a high current density of 100 mA cmgeo−2 show its super-stable performance with only 7 mV increase in overpotential after more than 60 hours of measurement, surpassing commercial Pt/C (increase of 170 mV). By partial substitution, the derived antiperovskite nitride achieves a smaller kinetic barrier of water dissociation compared to the unsubstituted InNNi3 and CuNNi3, revealed by first-principle calculations. It is found that the partially substituted CuxIn1−xNNi3 possesses a thermal neutral and desirable Gibbs free energy of hydrogen for HER, ascribed to the tailoring of the energy of d-band center arose by the A-site (A=Cu or In) substitution and a resulting optimization of adsorbate interactions. 相似文献
999.
Fei Du Shi-Jun Li Kun Jiang Rong Zeng Prof. Xi-Chun Pan Prof. Dr. Yu Lan Prof. Dr. Ying-Chun Chen Prof. Dr. Ye Wei 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):23963-23970
We have rationally designed a new class of alkyne-tethered oximes and applied them in an unprecedented iron-catalyzed radical relay protocol for the rapid assembly of a wide array of structurally new and interesting fused pyridines. This method shows broad substrate scope and good functional-group tolerance and enabled the synthesis of several biologically active molecules. Furthermore, the fused pyridines could be diversely functionalized through various simple transformations, such as cyclization, C−H alkylation, and a click reaction. DFT calculation studies indicate that the reactions involve cascade 1,5-hydrogen atom transfer, 5-exo-dig radical addition, and cyclization processes. Moreover, preliminary biological investigations suggest that some of the fused pyridines exhibit good anti-inflammatory activity by restoring the imbalance of inflammatory homeostasis of macrophages in a lipopolysaccharide-induced model. 相似文献
1000.
Dr. Yanmei Shi Wei Du Dr. Wei Zhou Dr. Changhong Wang Shanshan Lu Dr. Siyu Lu Prof. Bin Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(50):22656-22660
Transition metal chalcogenides (TMCs) are efficient oxygen evolution reaction (OER) pre-electrocatalysts, and will in situ transform into metal (oxy)hydroxides under OER condition. However, the role of chalcogen is not fully elucidated after oxidation and severe leaching. Here we present the vital promotion of surface-adsorbed chalcogenates on the OER activity. Taking NiSe2 as an example, in situ Raman spectroscopy revealed the oxidation of Se-Se to selenites (SeO32−) then to selenates (SeO42−). Combining the severe Se leaching and the strong signal of selenates, it is assumed that the selenates are rich on the surface and play significant roles. As expected, adding selenites to the electrolyte of Ni(OH)2 dramatically enhance its OER activity. And sulfates also exhibit the similar effect, suggesting the promotion of surface-adsorbed chalcogenates on OER is universal. Our findings offer unique insight into the transformation mechanism of materials during electrolysis. 相似文献