Angewandte Chemie

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Intrinsic Electrocatalytic Activity for Oxygen Evolution of Crystalline 3d‐Transition Metal Layered Double Hydroxides
Angewandte Chemie - Tập 133 Số 26 - Trang 14567-14578 - 2021
Fabio Dionigi, Jing Zhu, Zhenhua Zeng, Thomas Merzdorf, Hannes Sarodnik, Manuel Gliech, Lujin Pan, Wei‐Xue Li, Jeffrey Greeley, Peter Strasser
AbstractLayered double hydroxides (LDHs) are among the most active and studied catalysts for the oxygen evolution reaction (OER) in alkaline electrolytes. However, previous studies have generally either focused on a small number of LDHs, applied synthetic routes with limited structural control, or used non‐intrinsic activity metrics, thus hampering the construction of consistent structure–activity‐relations. Herein, by employing new individually developed synthesis strategies with atomic structural control, we obtained a broad series of crystalline α‐MA(II)MB(III) LDH and β‐MA(OH)2 electrocatalysts (MA=Ni, Co, and MB=Co, Fe, Mn). We further derived their intrinsic activity through electrochemical active surface area normalization, yielding the trend NiFe LDH > CoFe LDH > Fe‐free Co‐containing catalysts > Fe‐Co‐free Ni‐based catalysts. Our theoretical reactivity analysis revealed that these intrinsic activity trends originate from the dual‐metal‐site nature of the reaction centers, which lead to composition‐dependent synergies and diverse scaling relationships that may be used to design catalysts with improved performance.
Monodisperse Magnetic Single‐Crystal Ferrite Microspheres
Angewandte Chemie - Tập 117 Số 18 - Trang 2842-2845 - 2005
Hong Deng, Nian Bing Li, Qing Peng, Xun Wang, Jinping Chen, Yadong Li
3,8‐Methanoaza[10]annulen (Homoisochinolin)
Angewandte Chemie - Tập 97 Số 7 - Trang 592-594 - 1985
Werner Tückmantel, Gertraud Andree, Andreas Seidel, Hans Schmickler, Johann Lex, Elfi Kraka, Michael Haug, Dieter Cremer, Emanuel Vogel
Das zweite Aza‐Analogon von 1,6‐Methano[10]annulen, das „Homoisochionolin”︁ 2, wurde auf vielstufigem Weg über 3 synthetisiert. Anders als 1 polymerisiert 2 auch bei Luftausschluß schnell. Nach Spektren und Röntgen‐Strukturanalyse (eines Derivats) ist 2 eine aromatische Verbindung. magnified image
Atomically Thin Arsenene and Antimonene: Semimetal–Semiconductor and Indirect–Direct Band‐Gap Transitions
Angewandte Chemie - Tập 127 Số 10 - Trang 3155-3158 - 2015
Shengli Zhang, Zhong Yan, Yafei Li, Zhongfang Chen, Haibo Zeng
AbstractThe typical two‐dimensional (2D) semiconductors MoS2, MoSe2, WS2, WSe2 and black phosphorus have garnered tremendous interest for their unique electronic, optical, and chemical properties. However, all 2D semiconductors reported thus far feature band gaps that are smaller than 2.0 eV, which has greatly restricted their applications, especially in optoelectronic devices with photoresponse in the blue and UV range. Novel 2D mono‐elemental semiconductors, namely monolayered arsenene and antimonene, with wide band gaps and high stability were now developed based on first‐principles calculations. Interestingly, although As and Sb are typically semimetals in the bulk, they are transformed into indirect semiconductors with band gaps of 2.49 and 2.28 eV when thinned to one atomic layer. Significantly, under small biaxial strain, these materials were transformed from indirect into direct band‐gap semiconductors. Such dramatic changes in the electronic structure could pave the way for transistors with high on/off ratios, optoelectronic devices working under blue or UV light, and mechanical sensors based on new 2D crystals.
Simultaneous Fenton‐like Ion Delivery and Glutathione Depletion by MnO<sub>2</sub>‐Based Nanoagent to Enhance Chemodynamic Therapy
Angewandte Chemie - Tập 130 Số 18 - Trang 4996-5000 - 2018
Lisen Lin, Jibin Song, Liang Song, Kaimei Ke, Yijing Liu, Zijian Zhou, Zheyu Shen, Juan Li, Zhèn Yáng, Wei Tang, Gang Niu, Huanghao Yang, Xiaoyuan Chen
AbstractChemodynamic therapy (CDT) utilizes iron‐initiated Fenton chemistry to destroy tumor cells by converting endogenous H2O2 into the highly toxic hydroxyl radical (.OH). There is a paucity of Fenton‐like metal‐based CDT agents. Intracellular glutathione (GSH) with .OH scavenging ability greatly reduces CDT efficacy. A self‐reinforcing CDT nanoagent based on MnO2 is reported that has both Fenton‐like Mn2+ delivery and GSH depletion properties. In the presence of HCO3, which is abundant in the physiological medium, Mn2+ exerts Fenton‐like activity to generate .OH from H2O2. Upon uptake of MnO2‐coated mesoporous silica nanoparticles (MS@MnO2 NPs) by cancer cells, the MnO2 shell undergoes a redox reaction with GSH to form glutathione disulfide and Mn2+, resulting in GSH depletion‐enhanced CDT. This, together with the GSH‐activated MRI contrast effect and dissociation of MnO2, allows MS@MnO2 NPs to achieve MRI‐monitored chemo–chemodynamic combination therapy.
Selective Etching of Silicon from Ti<sub>3</sub>SiC<sub>2</sub> (MAX) To Obtain 2D Titanium Carbide (MXene)
Angewandte Chemie - Tập 130 Số 19 - Trang 5542-5546 - 2018
Mohamed Alhabeb, Kathleen Maleski, Tyler S. Mathis, Asia Sarycheva, Christine B. Hatter, Simge Uzun, Ariana Levitt, Yury Gogotsi
AbstractUntil now, MXenes could only be produced from MAX phases containing aluminum, such as Ti3AlC2. Here, we report on the synthesis of Ti3C2 (MXene) through selective etching of silicon from titanium silicon carbide—the most common MAX phase. Liters of colloidal solutions of delaminated Ti3SiC2‐derived MXene (0.5–1.3 mg mL−1) were produced and processed into flexible and electrically conductive films, which show higher oxidation resistance than MXene synthesized from Ti3AlC2. This new synthesis method greatly widens the range of precursors for MXene synthesis.
Low‐Temperature Wafer‐Scale Production of ZnO Nanowire Arrays
Angewandte Chemie - Tập 115 Số 26 - Trang 3139-3142 - 2003
Lori E. Greene, Matt Law, Joshua E. Goldberger, Franklin Kim, Justin C. Johnson, Yanfeng Zhang, Richard J. Saykally, Peidong Yang
Phenoxy‐carben
Angewandte Chemie - Tập 73 Số 1 - Trang 27-27 - 1961
Ulrich Schöllkopf, A. Lerch
Aus der Chemie der Carbenoide und anderer thermolabiler Organolithium‐Verbindungen
Angewandte Chemie - Tập 84 Số 12 - Trang 557-570 - 1972
Gert Köbrich
AbstractOrganolithium‐Verbindungen sind unbeschadet ihres enormen Reaktionsvermögens thermisch recht stabil. Thermolabilität, also die Eigenschaft, sich bei niedriger Temperatur ohne Mitwirkung von Fremdmolekülen irreversibel zu verändern, ist an zusätzliche funktionelle Gruppen gebunden, die entweder zusammen mit dem Metallkation leicht eliminiert werden können, intramolekulare Umlagerungen bewirken, oder — intermolekular — Additionen und Substitutionen hervorrufen, an denen sich mehrere gleichartige Moleküle beteiligen. Thermolabile Organolithium‐Verbindungen sind vielfach als Zwischenprodukte wichtiger Reaktionen postuliert oder nachgewiesen worden und daher theoretisch und praktisch interessant. Gelegentlich gelingt es unter besonderen Vorkehrungen — naturgemäß vor allem bei tiefer Temperatur — sie unzersetzt darzustellen und sie damit aus dem Zwang des ihnen als kurzlebigen Intermediaten beschiedenen Schicksals herauszulösen. Forschungen mit dieser Zielsetzung nehmen seit einigen Jahren breiten Raum in der Chemie der Organometall‐Verbindungen ein.
Phasengleichgewichte und kritische Kurven binärer Systeme aus Ammoniak und Kohlenwasserstoff
Angewandte Chemie - Tập 90 Số 10 - Trang 775-777 - 1978
H. Lentz, E. U. Franck
Tổng số: 163   
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