314 results
Search Results
302. Frontispiece: Building a Bridge from Papermaking to Solar Fuels.
- Author
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Jiang, Zaiyong, Zhang, Xinhan, Sun, Wei, Yang, Deren, Duchesne, Paul N., Gao, Yugang, Wang, Zeyan, Yan, Tingjiang, Yuan, Zhimin, Yang, Guihua, Ji, Xingxiang, Chen, Jiachuan, Huang, Baibiao, and Ozin, Geoffrey A.
- Subjects
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PAPERMAKING , *FUEL , *SULFATE waste liquor , *QUANTUM dots , *PHOTOREDUCTION - Published
- 2019
- Full Text
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303. Molecular Dipole Engineering of Carbonyl Additives for Efficient and Stable Perovskite Solar Cells.
- Author
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Jiang, Xiaoqing, Zhang, Bingqian, Yang, Guangyue, Zhou, Zhongmin, Guo, Xin, Zhang, Fengshan, Yu, Shitao, Liu, Shiwei, and Pang, Shuping
- Subjects
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SOLAR cells , *PEROVSKITE , *ADDITIVES , *PASSIVATION , *ENGINEERING - Abstract
Carbonyl functional materials as additives are extensively applied to reduce the defects density of the perovskite film. However, there is still a lack of comprehensive understanding for the effect of carbonyl additives to improve device performance. In this work, we systematically study the effect of carbonyl additive molecules on the passivation of defects in perovskite films. After a comprehensive investigation, the results confirm the importance of molecular dipole in amplifying the passivation effect of additive molecules. The additive with strong molecular dipole possesses the advantages of enhancing the efficiency and stability of perovskite solar cells (PSCs). After optimization, the companion efficiency of PSCs is 23.20 %, and it can maintain long‐term stability under harsh conditions. Additionally, a large‐area solar cell module‐modified DLBA was 20.18 % (14 cm2). This work provides an important reference for the selection and designing of efficient carbonyl additives. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
304. Photo‐Induced Switching of CO2 Hydrogenation Pathway towards CH3OH Production over Pt@UiO‐66‐NH2(Co).
- Author
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Chen, Jianmin, Wang, Yajing, Wang, Fengliang, and Li, Yingwei
- Subjects
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CHARGE exchange , *WATER-gas , *IRRADIATION , *CARBON dioxide , *HETEROGENEOUS catalysis , *HYDROGENATION - Abstract
It is highly desired to achieve controllable product selectivity in CO2 hydrogenation. Herein, we report light‐induced switching of reaction pathways of CO2 hydrogenation towards CH3OH production over actomically dispersed Co decorated Pt@UiO‐66‐NH2. CO, being the main product in the reverse water gas shift (RWGS) pathway under thermocatalysis condition, is switched to CH3OH via the formate pathway with the assistance of light irradiation. Impressively, the space‐time yield of CH3OH in photo‐assisted thermocatalysis (1916.3 μmol gcat−1 h−1) is about 7.8 times higher than that without light at 240 °C and 1.5 MPa. Mechanism investigation indicates that upon light irradiation, excited UiO‐66‐NH2 can transfer electrons to Pt nanoparticles and Co sites, which can efficiently catalyze the critical elementary steps (i.e. CO2‐to‐*HCOO conversion), thus suppressing the RWGS pathway to achieve a high CH3OH selectivity. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
305. Palladium‐Catalyzed Cascade Cyclization for the Synthesis of Fused Benzo‐Aza‐Oxa‐[5‐6‐5] Tetracycles.
- Author
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Liu, Chao, Tan, Xiangwen, Zhan, Lingzhi, Jing, Yaru, Wu, Wanqing, Ke, Zhuofeng, and Jiang, Huanfeng
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RING formation (Chemistry) , *CHEMICAL bonds , *NATURAL products , *DEUTERIUM , *ANILINE - Abstract
A novel and expedient cascade strategy has been demonstrated for the synthesis of fused benzo‐aza‐oxa‐[5‐6‐5] tetracycles in high yields and diastereoselectivities (up to 20 : 1 dr). The strategy was fulfilled through palladium‐catalyzed oxidative convergent assembly of functionally divergent anilines and 3‐butenoic acid with five chemical bonds constructed. Coupled with control experiments and deuterium labelled studies, DFT calculations were performed for the proposed mechanism. The utility of the illustrated strategy is emphasized by gram‐scale syntheses, late‐stage functionalization, and the transformation to a key core of natural products such as martinellic acid and seneciobipyrrolidine. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
306. Efficient Photoreduction of Diluted CO2 to Tunable Syngas by Ni−Co Dual Sites through d‐band Center Manipulation.
- Author
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Qian, Gan, Lyu, Wenyuan, Zhao, Xin, Zhou, Jingyi, Fang, Ruiqi, Wang, Fengliang, and Li, Yingwei
- Subjects
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SYNTHESIS gas , *PHOTOREDUCTION , *DENSITY functional theory , *VISIBLE spectra - Abstract
Photocatalytic conversion of CO2 into syngas is a promising way to address the energy and environmental challenges. Here we report the integration of Ni−Co dual sites on Ni doped Co3O4 ultrathin nanosheets assembled double‐hollow nanotube (Ni−Co3O4 NSDHN) for efficient photoreduction of low‐concentration CO2. Quasi in situ spectra and density functional theory calculations demonstrate that the declining of d‐band center of Ni−Co dual sites enables the electrons accumulation in the dxz/dyz‐2π* and dz2‐5σ orbitals. As a result, the binding strength of *CO is weakened and the *H adsorption site is modulated from metal sites to an oxygen site. Remarkably, Ni−Co3O4 NSDHN exhibits superior diluted CO2 photoconversion activity and controllable selectivity under the irradiation of visible light or even natural sunlight. A syngas evolution rate of 170.0 mmol g−1 h−1 with an apparent quantum yield of 3.7 % and continuously adjustable CO/H2 ratios from 1 : 10 to 10 : 1 are achieved. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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307. Back Cover: Translating Bacterial Detection by DNAzymes into a Litmus Test (Angew. Chem. Int. Ed. 47/2014).
- Author
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Tram, Kha, Kanda, Pushpinder, Salena, Bruno J., Huan, Shuangyan, and Li, Yingfu
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COLORIMETRY , *COLOR - Published
- 2014
- Full Text
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308. Nitrogen‐Doped Carbon Composites with Ordered Macropores and Hollow Walls.
- Author
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Yao, Wen, Chen, Jianmin, Wang, Yajing, Fang, Ruiqi, Qin, Ze, Yang, Xianfeng, Chen, Liyu, and Li, Yingwei
- Subjects
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METAL-organic frameworks , *CARBON composites , *MASS transfer , *METAL fabrication , *CATALYTIC activity , *HYDROGENATION - Abstract
Metal‐organic frameworks provide versatile templates for the fabrication of various metal/carbon materials, but most of the derived composites possess only microspores, limiting the accessibility of embedded active sites. Herein, we report the construction of cobalt/nitrogen‐doped carbon composites with a three‐dimensional (3D) ordered macroporous and hollow‐wall structure (H‐3DOM‐Co/NC) using a single‐crystal ordered macropore (SOM)‐ZIF‐8@ZIF‐67 as precursor. During the pyrolysis, the interconnected macroporous structure of SOM‐ZIF‐8@ZIF‐67 is mostly preserved, whereas the pore wall achieves a solid‐to‐hollow transformation with Co nanoparticles formed in the hollow walls. The 3D‐ordered macroporous carbon skeleton may effectively promote long‐range mass transfer and the hollow wall can facilitate local accessibility of active sites. This unique structure can greatly boost its catalytic activity in the selective hydrogenation of biomass‐derived furfural to cyclopentanol, much superior to its counterparts without this well‐designed hierarchically porous structure. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
309. Metal Sub‐nanoclusters Confined within Hierarchical Porous Carbons with High Oxidation Activity.
- Author
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Zhao, Xin, Kong, Xiangpeng, Wang, Fengliang, Fang, Ruiqi, and Li, Yingwei
- Subjects
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MALEIC acid , *POROUS metals , *METALS , *LAMINATED metals , *FERMI level , *METAL-organic frameworks , *CATALYTIC activity - Abstract
Metal sub‐nanoclusters (SNCs) have shown great promise for a variety of catalytic reactions. However, the fabrication of stable metal SNCs simultaneously with high dispersion and high metal contents remains a challenge. Herein, we report a novel and versatile strategy for the synthesis of various bimetal SNCs stabilized within hierarchical porous carbons (HPC). This facile synthesis only involves the self‐assembly of a metal‐organic framework (MOF) as the precursor, a molten salt assisted pyrolysis process and the final metal replacement. The metal SNCs (mostly less than 0.8 nm) derived from the metal nodes of the MOF are exclusively confined and homogeneously dispersed throughout the organic ligands derived HPC at high loadings (up to 11.2 wt %). The obtained Cu‐Pd@HPC composite exhibits superior catalytic activity and recycling durability in the selective transformation of furfural to maleic acid, achieving 97.8 % yield of maleic acid with a TOF value as high as 20.1 h−1 under mild conditions. DFT calculations reveal that the introduction of Pd shifts the partial density of states of Cu toward the Fermi level, leading to stronger chemisorption of furfural to enhance the catalytic activity. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
310. Photo‐responsive Helical Motion by Light‐Driven Molecular Motors in a Liquid‐Crystal Network.
- Author
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Hou, Jiaxin, Mondal, Anirban, Long, Guiying, Haan, Laurens, Zhao, Wei, Zhou, Guofu, Liu, Danqing, Broer, Dirk J., Chen, Jiawen, and Feringa, Ben L.
- Subjects
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MOLECULAR motor proteins , *SMALL molecules , *SOFT robotics , *ENERGY conversion , *CHOLESTERIC liquid crystals , *CHIRALITY , *POLYMER liquid crystals - Abstract
Controlling sophisticated motion by molecular motors is a major goal on the road to future actuators and soft robotics. Taking inspiration from biological motility and mechanical functions common to artificial machines, responsive small molecules have been used to achieve macroscopic effects, however, translating molecular movement along length scales to precisely defined linear, twisting and rotary motions remain particularly challenging. Here, we present the design, synthesis and functioning of liquid‐crystal network (LCN) materials with intrinsic rotary motors that allow the conversion of light energy into reversible helical motion. In this responsive system the photochemical‐driven molecular motor has a dual function operating both as chiral dopant and unidirectional rotor amplifying molecular motion into a controlled and reversible left‐ or right‐handed macroscopic twisting movement. By exploiting the dynamic chirality, directionality of motion and shape change of a single motor embedded in an LC‐network, complex mechanical motions including bending, walking and helical motion, in soft polymer materials are achieved which offers fascinating opportunities toward inherently photo‐responsive materials. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
311. 2‐Methoxyhydroquinone from Vanillin for Aqueous Redox‐Flow Batteries.
- Author
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Schlemmer, Werner, Nothdurft, Philipp, Petzold, Alina, Riess, Gisbert, Frühwirt, Philipp, Schmallegger, Max, Gescheidt‐Demner, Georg, Fischer, Roland, Freunberger, Stefan A., Kern, Wolfgang, and Spirk, Stefan
- Subjects
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FLOW batteries , *VANILLIN , *QUINONE derivatives , *OXIDATION-reduction reaction , *AQUEOUS electrolytes , *QUINONE , *SEMIQUINONE - Abstract
We show the synthesis of a redox‐active quinone, 2‐methoxy‐1,4‐hydroquinone (MHQ), from a bio‐based feedstock and its suitability as electrolyte in aqueous redox flow batteries. We identified semiquinone intermediates at insufficiently low pH and quinoid radicals as responsible for decomposition of MHQ under electrochemical conditions. Both can be avoided and/or stabilized, respectively, using H3PO4 electrolyte, allowing for reversible cycling in a redox flow battery for hundreds of cycles. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
312. A Truxenone‐based Covalent Organic Framework as an All‐Solid‐State Lithium‐Ion Battery Cathode with High Capacity.
- Author
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Yang, Xiye, Hu, Yiming, Dunlap, Nathan, Wang, Xubo, Huang, Shaofeng, Su, Zhiping, Sharma, Sandeep, Jin, Yinghua, Huang, Fei, Wang, Xiaohui, Lee, Se‐hee, and Zhang, Wei
- Subjects
- *
LITHIUM-ion batteries , *CATHODES , *ENERGY storage , *OXIDATION-reduction reaction , *CARBONYL group , *CRYSTAL structure , *LITHIUM ions - Abstract
All‐solid‐state lithium ion batteries (LIBs) are ideal for energy storage given their safety and long‐term stability. However, there is a limited availability of viable electrode active materials. Herein, we report a truxenone‐based covalent organic framework (COF‐TRO) as cathode materials for all‐solid‐state LIBs. The high‐density carbonyl groups combined with the ordered crystalline COF structure greatly facilitate lithium ion storage via reversible redox reactions. As a result, a high specific capacity of 268 mAh g−1, almost 97.5 % of the calculated theoretical capacity was achieved. To the best of our knowledge, this is the highest capacity among all COF‐based cathode materials for all‐solid‐state LIBs reported so far. Moreover, the excellent cycling stability (99.9 % capacity retention after 100 cycles at 0.1 C rate) shown by COF‐TRO suggests such truxenone‐based COFs have great potential in energy storage applications. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
313. A Truxenone‐based Covalent Organic Framework as an All‐Solid‐State Lithium‐Ion Battery Cathode with High Capacity.
- Author
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Yang, Xiye, Hu, Yiming, Dunlap, Nathan, Wang, Xubo, Huang, Shaofeng, Su, Zhiping, Sharma, Sandeep, Jin, Yinghua, Huang, Fei, Wang, Xiaohui, Lee, Se‐hee, and Zhang, Wei
- Abstract
All‐solid‐state lithium ion batteries (LIBs) are ideal for energy storage given their safety and long‐term stability. However, there is a limited availability of viable electrode active materials. Herein, we report a truxenone‐based covalent organic framework (COF‐TRO) as cathode materials for all‐solid‐state LIBs. The high‐density carbonyl groups combined with the ordered crystalline COF structure greatly facilitate lithium ion storage via reversible redox reactions. As a result, a high specific capacity of 268 mAh g−1, almost 97.5 % of the calculated theoretical capacity was achieved. To the best of our knowledge, this is the highest capacity among all COF‐based cathode materials for all‐solid‐state LIBs reported so far. Moreover, the excellent cycling stability (99.9 % capacity retention after 100 cycles at 0.1 C rate) shown by COF‐TRO suggests such truxenone‐based COFs have great potential in energy storage applications. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
314. Copper-Catalyzed C(sp3)−H/C(sp3)−H Cross-Dehydrogenative Coupling with Internal Oxidants: Synthesis of 2-Trifluoromethyl-Substituted Dihydropyrrol-2-ols.
- Author
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Zhu, Chuanle, Zhu, Rui, Zeng, Hao, Chen, Fulin, Liu, Chi, Wu, Wanqing, and Jiang, Huanfeng
- Subjects
- *
COUPLING reactions (Chemistry) , *COPPER , *OXIMES , *ACETATES , *PYRIDAZINES - Abstract
The first oxidative C(sp3)−H/C(sp3)−H cross-dehydrogenative coupling (CDC) reaction promoted by an internal oxidant is reported. This copper-catalyzed CDC reaction of oxime acetates and trifluoromethyl ketones provides a simple and efficient approach towards 2-trifluoromethyldihydropyrrol-2-ol derivatives in a highly diastereoselective manner by cascade C(sp3)−C(sp3) bond formation and cyclization. These products were further transformed into various significant and useful trifluoromethylated heterocyclic compounds, such as trifluoromethylated furan, thiophene, pyrrole, dihydropyridazine, and pyridazine derivatives. A trifluoromethylated analogue of an Aβ42 lowering agent was also synthesized smoothly. Preliminary mechanistic studies indicated that this reaction involves a copper(I)/copper(III) catalytic cycle with the oxime acetate acting as an internal oxidant. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
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