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981.
Hao Zhang Wei Xia Haoming Shen Wenhan Guo Zibin Liang Kexin Zhang Yingxiao Wu Bingjun Zhu Ruqiang Zou 《Angewandte Chemie (International ed. in English)》2020,59(5):1871-1877
Antiperovskite Co3InC0.7N0.3 nanomaterials with highly enhanced oxygen reduction reaction (ORR) performance were prepared by tuning nitrogen contents through a metal–organic framework (MOF)‐derived strategy. The nanomaterial surpasses all reported noble‐metal‐free antiperovskites and even most perovskites in terms of onset potential (0.957 V at J=0.1 mA cm?2) and half‐wave potential (0.854 V). The OER and zinc–air battery performance demonstrate its multifunctional oxygen catalytic activities. DFT calculation was performed and for the first time, a 4 e? dissociative ORR pathway on (200) facets of antiperovskite was revealed. Free energy studies showed that nitrogen substitution could strengthen the OH desorption as well as hydrogenation that accounts for the enhanced ORR performance. This work expands the scope for material design via tailoring the nitrogen contents for optimal reaction free energy and hence performance of the antiperovskite system. 相似文献
982.
Luis M. Mateo Qiang Sun Shi‐Xia Liu Jesse J. Bergkamp Kristjan Eimre Carlo A. Pignedoli Pascal Ruffieux Silvio Decurtins Giovanni Bottari Roman Fasel Tomas Torres 《Angewandte Chemie (International ed. in English)》2020,59(3):1334-1339
On‐surface synthesis offers a versatile approach to prepare novel carbon‐based nanostructures that cannot be obtained by conventional solution chemistry. Graphene nanoribbons (GNRs) have potential for a variety of applications. A key issue for their application in molecular electronics is in the fine‐tuning of their electronic properties through structural modifications, such as heteroatom doping or the incorporation of non‐benzenoid rings. In this context, the covalent fusion of GNRs and porphyrins (Pors) is a highly appealing strategy. Herein we present the selective on‐surface synthesis of a Por–GNR hybrid, which consists of two Pors connected by a short GNR segment. The atomically precise structure of the Por–GNR hybrid has been characterized by bond‐resolved scanning tunneling microscopy (STM) and noncontact atomic force microscopy (nc‐AFM). The electronic properties have been investigated by scanning tunneling spectroscopy (STS), in combination with DFT calculations, which reveals a low electronic gap of 0.4 eV. 相似文献
983.
Peng‐Ju Xia Dan Song Zhi‐Peng Ye Yuan‐Zhuo Hu Jun‐An Xiao Hao‐Yue Xiang Xiao‐Qing Chen Hua Yang 《Angewandte Chemie (International ed. in English)》2020,59(17):6706-6710
A photoinduced SET process enables the direct B?H bond activation of NHC–boranes. In contrast to common hydrogen atom transfer (HAT) strategies, this photoinduced reaction simply takes advantage of the beneficial redox potentials of NHC–boranes, thus obviating the need for extra radical initiators. The resulting NHC–boryl radical was used for the borylation of a wide range of α‐trifluoromethylalkenes and alkenes with diverse electronic and structural features, providing facile access to highly functionalized borylated molecules. Labeling and photoquenching experiments provide insight into the mechanism of this photoinduced SET pathway. 相似文献
984.
Jin‐Xia Liang Jian Lin Jingyue Liu Xiaodong Wang Tao Zhang Jun Li 《Angewandte Chemie (International ed. in English)》2020,59(31):12868-12875
Herein, we report a theoretical and experimental study of the water‐gas shift (WGS) reaction on Ir1/FeOx single‐atom catalysts. Water dissociates to OH* on the Ir1 single atom and H* on the first‐neighbour O atom bonded with a Fe site. The adsorbed CO on Ir1 reacts with another adjacent O atom to produce CO2, yielding an oxygen vacancy (Ovac). Then, the formation of H2 becomes feasible due to migration of H from adsorbed OH* toward Ir1 and its subsequent reaction with another H*. The interaction of Ir1 and the second‐neighbouring Fe species demonstrates a new WGS pathway featured by electron transfer at the active site from Fe3+?O???Ir2+?Ovac to Fe2+?Ovac???Ir3+?O with the involvement of Ovac. The redox mechanism for WGS reaction through a dual metal active site (DMAS) is different from the conventional associative mechanism with the formation of formate or carboxyl intermediates. The proposed new reaction mechanism is corroborated by the experimental results with Ir1/FeOx for sequential production of CO2 and H2. 相似文献
985.
Pengfei Xia Shaowen Cao Bicheng Zhu Mingjin Liu Miusi Shi Jiaguo Yu Yufeng Zhang 《Angewandte Chemie (International ed. in English)》2020,59(13):5218-5225
Constructing heterojunctions between two semiconductors with matched band structure is an effective strategy to acquire high‐efficiency photocatalysts. The S‐scheme heterojunction system has shown great potential in facilitating separation and transfer of photogenerated carriers, as well as acquiring strong photoredox ability. Herein, a 0D/2D S‐Scheme heterojunction material involving CeO2 quantum dots and polymeric carbon nitride (CeO2/PCN) is designed and constructed by in situ wet chemistry with subsequent heat treatment. This S‐scheme heterojunction material shows high‐efficiency photocatalytic sterilization rate (88.1 %) towards Staphylococcus aureus (S. aureus) under visible‐light irradiation (λ≥420 nm), which is 2.7 and 8.2 times that of pure CeO2 (32.2 %) and PCN (10.7 %), respectively. Strong evidence of S‐scheme charge transfer path is verified by theoretical calculations, in situ irradiated X‐ray photoelectron spectroscopy, and electron paramagnetic resonance. 相似文献
986.
Qian Wei Rong Zhang Qin Wang Xin Jia Yan Quan Wei Yu Fu Xia Yan 《Natural product research》2020,34(9):1320-1325
AbstractAs part of our continuing efforts to explore bioactive compounds from natural resources, a new iridoid glycoside, adoxosidic acid-6′-oleuroperic ester (1), together with one known phenylethanoid glycoside (2) and two known flavonoid glycosides (3–4) were isolated from the fruit of Forsythia suspensa. The structure of the new compound (1) was elucidated through 1D and 2D NMR spectroscopic data and HR-ESIMS. Interestingly, compound 1 was a monoterpene ester of one iridoid glycoside. Compounds 2–4 were identified as calceolarioside A (2), kaempferol-3-O-rutinoside (3), kampferol-3-O-robinobioside (4) on the basis of NMR spectroscopic data analyses and comparison with the data reported in the literature. The antiviral activity aganisist influenza A (H5N1) virus of compound 1 was studied as well. 相似文献
987.
Ying Liu Ximing Rong Mingze Li Maxim S. Molokeev Jing Zhao Zhiguo Xia 《Angewandte Chemie (International ed. in English)》2020,59(28):11634-11640
The incorporation of impurity ions or doping is a promising method for controlling the electronic and optical properties and the structural stability of halide perovskite nanocrystals (NCs). Herein, we establish relationships between rare‐earth ions doping and intrinsic emission of lead‐free double perovskite Cs2AgInCl6 NCs to impart and tune the optical performances in the visible light region. Tb3+ ions were incorporated into Cs2AgInCl6 NCs and occupied In3+ sites as verified by both crystallographic analyses and first‐principles calculations. Trace amounts of Bi doping endowed the characteristic emission (5D4→7F6‐3) of Tb3+ ions with a new excitation peak at 368 nm rather than the single characteristic excitation at 290 nm of Tb3+. By controlling Tb3+ ions concentration, the emission colors of Bi‐doped Cs2Ag(In1?xTbx)Cl6 NCs could be continuously tuned from green to orange, through the efficient energy‐transfer channel from self‐trapped excitons to Tb3+ ions. Our study provides the salient features of the material design of lead‐free perovskite NCs and to expand their luminescence applications. 相似文献
988.
Hai‐Dong Xia Zhong‐Liang Li Qiang‐Shuai Gu Xiao‐Yang Dong Jia‐Heng Fang Xuan‐Yi Du Li‐Lei Wang Xin‐Yuan Liu 《Angewandte Chemie (International ed. in English)》2020,59(39):16926-16932
We describe a photoinduced copper‐catalyzed asymmetric radical decarboxylative alkynylation of bench‐stable N‐hydroxyphthalimide(NHP)‐type esters of racemic alkyl carboxylic acids with terminal alkynes, which provides a flexible platform for the construction of chiral C(sp3)?C(sp) bonds. Critical to the success of this process are not only the use of the copper catalyst as a dual photo‐ and cross‐coupling catalyst but also tuning of the NHP‐type esters to inhibit the facile homodimerization of the alkyl radical and terminal alkyne, respectively. Owing to the use of stable and easily available NHP‐type esters, the reaction features a broader substrate scope compared with reactions using the alkyl halide counterparts, covering (hetero)benzyl‐, allyl‐, and aminocarbonyl‐substituted carboxylic acid derivatives, and (hetero)aryl and alkyl as well as silyl alkynes, thus providing a vital complementary approach to the previously reported method. 相似文献
989.
Jun Hu Nan Zhang Pan‐Ke Zhang Yun Chen Xing‐Hua Xia Hong‐Yuan Chen Jing‐Juan Xu 《Angewandte Chemie (International ed. in English)》2020,59(41):18244-18248
We report a new mass spectrometric method for detecting electrogenerated intermediates. This approach is based on simultaneous activation of electrospray ionization and redox reaction on a wireless bipolar ultramicroelectrode, which is fabricated in the tip of a quartz nanopipette. The hollow structure of the ultramicroelectrode permits rapid transferring the transient species from electrode–electrolyte interfaces into the gas phase for mass spectrometric identification on the time scale of microseconds. The long‐sought fleeting intermediates including TPrA.+, whose lifetime in solution is only 200 μs, and catecholamine o‐semiquinone radicals, the second‐order rate constant of which is typically 109 m ?1 s?1, were successfully identified, helping clarify the previously hidden reaction pathways. Accordingly, our method may have wide applicability in exploring the dynamics of many electrochemical reactions, especially their ultrafast initial steps. 相似文献
990.
Chengfei Wang Xiaowei Li Ziquan Lv Yingyu Wang Yuebin Ke Xi Xia 《Journal of separation science》2020,43(12):2321-2329
A rapid and reliable method for the detection of five carbapenems (biapenem, imipenem, doripenem, meropenem, and faropenem) in water was developed and validated. After acidification of water samples with acetic acid, carbapenems were isolated using a Bond Elut PPL cartridge. The target compounds were separated using ultra high performance liquid chromatography with a chromatographic run time of 5 min and detected on a triple quadrupole mass spectrometer operated in positive electrospray ionization and multiple reaction monitoring mode. Mean recoveries were in the range of 76.6–106.5%, with satisfactory intraday and interday relative standard deviations lower than 10.0 and 10.8%, respectively. The limits of detection and quantification were in the ranges of 0.05–0.2 µg/L and 0.1–0.5 µg/L, respectively, depending on the analyte. The proposed method was applied to the analysis of river samples and wastewater samples from swine farms, and no carbapenems were detected in the collected samples. 相似文献