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51.
通常采用以氢氧化物作为造孔剂,过渡金属硝酸盐或氯化物作为石墨化催化剂的传统两步法策略制备多孔石墨化碳材料。然而制备过程中多涉及有毒和腐蚀性试剂,且多步骤的过程耗时较长。本文以双氰胺为原料通过热缩聚反应得到g-C3N4,采用高铁酸钾为催化剂一步法实现g-C3N4的同步碳化-石墨化,并研究其光催化性能。与传统的两步法相比,该方法耗时少、效率高、无污染。与初始的g-C3N4材料相比,石墨化g-C3N4衍生碳质材料不仅显著改善了可见光的吸收,而且大大增强了光催化活性。研究了不同石墨化温度对g-C3N4衍生碳质材料在可见光下降解甲基橙溶液的影响。700 ℃下制备的衍生碳质材料的降解率为12.4 mg/g。光电化学测试结果表明,多孔g-C3N4衍生碳质材料的光生载流子密度、电荷分离和光电流(提高了5.4倍)均得到显著提高。因此,该简便、灵活方法为提高g-C3N4衍生碳质材料的吸附和光催化性能提供了一种有前景的、高效的途径。 相似文献
52.
Wang Zhenya Chen Hui Yao Ligang Chen Xu Qi Xiaoli Zhang Jun 《Nonlinear dynamics》2021,106(3):2107-2130
Nonlinear Dynamics - Fault diagnosis of critical rotating machinery components is necessary to ensure safe operation. However, the commonly used rotating machinery fault diagnosis methods are... 相似文献
53.
Cheng Sheng Dr. Zheng Ling Dr. Tanveer Ahmad Prof. Dr. Fang Xie Prof. Dr. Wanbin Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(23):e202200128
Regioselective [3+3] annulation of alkynyl ketimines with α-cyano ketones for the synthesis of polysubstituted 4H-pyran derivatives with a quaternary CF3-containing center has been realized by using Cu(OAc)2 as the catalyst. The novel strategy tolerates a wide range of α-CF3 alkynyl ketimines and α-cyano ketones with both aryl and alkyl substitutents. A preliminary asymmetric synthesis of chiral product 3 has been attempted by using copper and chiral thiourea as the cocatalyst with excellent yields (86-99 %) and good enantioselectivities (71–78 % ee). Furthermore, product 3 aa could be obtained on a gram-scale reaction with 75 % yield and 99 % ee after recrystallization. Several products were also transformed readily. Control experiments indicate that the reaction involves a process with a base-catalyzed or chiral thiourea-catalyzed Mannich-type reaction followed by a highly regioselective copper-catalyzed ring-closing reaction on the alkynyl moiety in a 6-endo-dig fashion. 相似文献
54.
Polystyrene-supported 2-azidoethyl phenyl selenide and 3-azidopropyl phenyl selenide reagents have been developed and applied to the traceless solid-phase organic synthesis of 1-vinyl- and 1-allyl-1,2,3-triazoles by CuI-mediated azide–alkyne cycloadditions and subsequent cleavage from the polymer support through oxidation–elimination reaction with 30% hydrogen peroxide. The advantages of this method include straightforward operation, good yield and purity of the products, and good stability and lack of odor for the reagents. 相似文献
55.
Ming-Qiang Huang Huan-Huan Wang Xiao-Bin Shan Liu-Si Sheng Chang-Jin Hu Xue-Jun Gu Wei-Jun Zhang 《中国化学会会志》2023,70(4):938-948
Secondary organic aerosol (SOA) produced by ozonolysis of styrene and other alkene compounds is a major part of fine particles in urban atmospheres. The atmospheric ozonolysis process of styrene is simulated in a smog chamber, and the formed SOA particles are detected on-line by a synchronous radiation vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) in this study. Through molecular ion peaks in the photonionization mass spectra of SOA and the corresponding photoionization efficiency curve, combined with off-line measurement verification of ultraviolet visible and infrared absorption spectra, it is determined that formaldehyde, formic acid, benzene, phenol, benzaldehyde, and benzoic acid are the main constituents of styrene SOA. These provide new information for studying the atmospheric ozonolysis oxidation mechanism of styrene. VUV-PIMS can get over complicated sample preparation procedures, secondary pollution, and other shortcomings of the off-line method and is a useful instrument to measure constituents and unveil the formation process of SOA particles. 相似文献
56.
Shuangxi Jing Ren Sheng Dr. Xinxin Liang Prof. Dong Gu Dr. Yuhao Peng Prof. Juanxiu Xiao Prof. Yijun Shen Prof. Di Hu Prof. Wei Xiao 《Angewandte Chemie (International ed. in English)》2023,62(6):e202216315
An overall carbon-neutral CO2 electroreduction requires enhanced conversion efficiency and intensified functionality of CO2-derived products to balance the carbon footprint from CO2 electroreduction against fixed CO2. A liquid Sn cathode is herein introduced into electrochemical reduction of CO2 in molten salts to fabricate core–shell Sn−C spheres (Sn@C). An in situ generated Li2SnO3/C directs a self-template formation of Sn@C. Benefitting from the accelerated reaction kinetics from the liquid Sn cathode and the core–shell structure of Sn@C, a CO2-fixation current efficiency higher than 84 % and a high reversible lithium-storage capacity of Sn@C are achieved. The versatility of this strategy is demonstrated by other low melting point metals, such as Zn and Bi. This process integrates energy-efficient CO2 conversion and template-free fabrication of value-added metal-carbon, achieving an overall carbon-neutral electrochemical reduction of CO2. 相似文献
57.
Ye Qian Mi Wei Deng Chaohui He Prof. Dr. Osman Eksik Yi Ping Zheng De Kun Yao Dr. Xian Bin Liu Yan Hong Yin Ye Sheng Li Prof. Dr. Bao Yu Xia Prof. Dr. Zi Ping Wu 《Angewandte Chemie (International ed. in English)》2023,62(12):e202218621
Solid-state lithium batteries are promising and safe energy storage devices for mobile electronics and electric vehicles. In this work, we report a facile in situ polymerization of 1,3-dioxolane electrolytes to fabricate integrated solid-state lithium batteries. The in situ polymerization and formation of solid-state dioxolane electrolytes on interconnected carbon nanotubes (CNTs) and active materials is the key to realizing a high-performance battery with excellent interfacial contact among CNTs, active materials and electrolytes. Therefore, the electrodes could be tightly integrated into batteries through the CNTs and electrolyte. Electrons/ions enable full access to active materials in the whole electrode. Electrodes with a low resistance of 4.5 Ω □−1 and high lithium-ion diffusion efficiency of 2.5×10−11 cm2 s−1 can significantly improve the electrochemical kinetics. Subsequently, the batteries demonstrated high energy density, amazing charge/discharge rate and long cycle life. 相似文献
58.
Dr. Huanhuan Shi Prof. Mengmeng Li Shuai Fu Dr. Christof Neumann Dr. Xiaodong Li Dr. Wenhui Niu Yunji Lee Prof. Mischa Bonn Dr. Hai I. Wang Prof. Andrey Turchanin Dr. Ali Shaygan Nia Dr. Sheng Yang Prof. Xinliang Feng 《Angewandte Chemie (International ed. in English)》2023,62(28):e202303929
Two-dimensional van der Waals heterostructures (2D vdWHs) have recently gained widespread attention because of their abundant and exotic properties, which open up many new possibilities for next-generation nanoelectronics. However, practical applications remain challenging due to the lack of high-throughput techniques for fabricating high-quality vdWHs. Here, we demonstrate a general electrochemical strategy to prepare solution-processable high-quality vdWHs, in which electrostatic forces drive the stacking of electrochemically exfoliated individual assemblies with intact structures and clean interfaces into vdWHs with strong interlayer interactions. Thanks to the excellent combination of strong light absorption, interfacial charge transfer, and decent charge transport properties in individual layers, thin-film photodetectors based on graphene/In2Se3 vdWHs exhibit great promise for near-infrared (NIR) photodetection, owing to a high responsivity (267 mA W−1), fast rise (72 ms) and decay (426 ms) times under NIR illumination. This approach enables various hybrid systems, including graphene/In2Se3, graphene/MoS2 and graphene/MoSe2 vdWHs, providing a broad avenue for exploring emerging electronic, photonic, and exotic quantum phenomena. 相似文献
59.
Dr. Jin-Bo Pan Bing-Hao Wang Dr. Sheng Shen Dr. Lang Chen Prof. Dr. Shuang-Feng Yin 《Angewandte Chemie (International ed. in English)》2023,62(38):e202307246
Core-shell photoanodes have shown great potential for photoelectrochemical (PEC) water oxidation. However, the construction of a high-quality interface between the core and shell, as well as a highly catalytic surface, remains a challenge. Herein, guided by computation, we present a BiVO4 photoanode coated with ZnCoFe polyphthalocyanine using pyrazine as a coordination agent. The bidirectional axial coordination of pyrazine plays a dual role by facilitating intimate interfacial contact between BiVO4 and ZnCoFe polyphthalocyanine, as well as regulating the electron density and spin configuration of metal sites in ZnCoFe phthalocyanine, thereby promoting the potential-limiting step of *OOH desorption. The resulting photoanode displayed a high photocurrent density of 5.7±0.1 mA cm−2 at 1.23 VRHE. This study introduces a new approach for constructing core–shell photoanodes, and uncovers the key role of pyrazine axial coordination in modulating the catalytic activity of metal phthalocyanine. 相似文献
60.
Weiqing Xu Yu Wu Yuling Xu Dr. Xiaoli Cai Prof. Wenling Gu Prof. Chengzhou Zhu 《Angewandte Chemie (International ed. in English)》2023,62(47):e202308827
Enzymatic catalysis with high efficiency allows them a great prospect in metabolite monitoring in living cells. However, complex tumor microenvironments, such as acidity, H2O2, and hypoxia, are bound to disturb catalytic reactions for misleading results. Here, we report a spatially compartmentalized artificial organelle to correct intratumoral glucose analysis, where the zeolitic imidazolate framework-8 immobilized glucose oxidase-horseradish peroxidase cascade core and catalase-directed shell act as signal transduction and guarding rooms respectively. The acid-digested core and stable shell provide appropriate spaces to boost biocatalytic efficiency with good tolerability. Notably, the endogenous H2O2 is in situ decomposed to O2 by catalase, which not only overcomes the interference in signal output but also alleviates the hypoxic states to maximize glucose oxidation. The marked protective effect and biocompatibility render artificial organelles to correct the signal transduction for dynamic monitoring glucose in vitro and in vivo, achieving our goal of accurate intratumoral metabolite analysis. 相似文献