331 results on '"Jun Li"'
Search Results
2. Enantioselective Synthesis of Inherently Chiral Calix[4]arenes via Palladium-Catalyzed Asymmetric Intramolecular C–H Arylations
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Yu-Zhen Zhang, Meng-Meng Xu, Xu-Ge Si, Jun-Li Hou, and Quan Cai
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Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Catalysis - Abstract
We report herein an efficient approach for the enantioselective synthesis of inherently chiral calix[4]arenes via palladium-catalyzed asymmetric intramolecular C-H arylations. Using a chiral bifunctional phosphine-carboxylate ligand, the inherent chirality on macrocyclic scaffolds was induced successfully, from which a wide range of calix[4]arenes with fluorenone motifs were obtained with good yields and excellent enantioselectivities (up to99% ee). The synthetic utility of this method was demonstrated by diverse transformations of the products, thus substantially expanding the chemical space of chiral calix[4]arenes. Further investigations of photophysical and chiroptical properties revealed that calix[4]arenes bearing two fluorenone moieties displayed remarkable
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- 2022
3. Metal Affinity of Support Dictates Sintering of Gold Catalysts
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Jin-Cheng Liu, Langli Luo, Hai Xiao, Junfa Zhu, Yang He, and Jun Li
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Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Catalysis - Abstract
Sintering during heterogeneous catalytic reactions is one of the most notorious deactivation channels in catalysts of supported metal nanoparticles. It is therefore critical to understand the effect of support on the sintering behavior. Here, by using
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- 2022
4. Mechanistic Insights into OC–COH Coupling in CO2 Electroreduction on Fragmented Copper
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Kaili Yao, Jun Li, Haibin Wang, Ruihu Lu, Xiaotao Yang, Mingchuan Luo, Ning Wang, Ziyun Wang, Changxu Liu, Tan Jing, Songhua Chen, Emiliano Cortés, Stefan A. Maier, Sheng Zhang, Tieliang Li, Yifu Yu, Yongchang Liu, Xinchen Kang, and Hongyan Liang
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Science & Technology ,Chemistry, Multidisciplinary ,F100 ,CATALYSTS ,H800 ,General Chemistry ,NANOSHEETS ,Biochemistry ,Catalysis ,Chemistry ,ELECTROCHEMICAL REDUCTION ,Colloid and Surface Chemistry ,SELECTIVITY ,DEPENDENCE ,Physical Sciences ,SPECTROSCOPIC OBSERVATION ,03 Chemical Sciences ,CU - Abstract
The carbon–carbon (C–C) bond formation is essential for the electroconversion of CO2 into high-energy-density C2+ products, and the precise coupling pathways remain controversial. Although recent computational investigations have proposed that the OC–COH coupling pathway is more favorable in specific reaction conditions than the well-known CO dimerization pathway, the experimental evidence is still lacking, partly due to the separated catalyst design and mechanistic/spectroscopic exploration. Here, we employ density functional theory calculations to show that on low-coordinated copper sites, the *CO bindings are strengthened, and the adsorbed *CO coupling with their hydrogenation species, *COH, receives precedence over CO dimerization. Experimentally, we construct a fragmented Cu catalyst with abundant low-coordinated sites, exhibiting a 77.8% Faradaic efficiency for C2+ products at 300 mA cm–2. With a suite of in situ spectroscopic studies, we capture an *OCCOH intermediate on the fragmented Cu surfaces, providing direct evidence to support the OC–COH coupling pathway. The mechanistic insights of this research elucidate how to design materials in favor of OC–COH coupling toward efficient C2+ production from CO2 reduction.
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- 2022
5. SO2/NO2 Separation Driven by NO2 Dimerization on SSZ-13 Zeolite Membrane
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Ziyi Li, Jun Li, Huazhen Rong, Jiayu Zuo, Xiong Yang, Yi Xing, Yingshu Liu, Guangshan Zhu, and Xiaoqin Zou
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Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Catalysis - Published
- 2022
6. Boryl Radical Activation of Benzylic C–OH Bond: Cross-Electrophile Coupling of Free Alcohols and CO2 via Photoredox Catalysis
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Wen-Duo Li, Yang Wu, Shi-Jun Li, Yi-Qian Jiang, Yan-Lin Li, Yu Lan, and Ji-Bao Xia
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Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Catalysis - Published
- 2022
7. Ultra-Efficient Americium/Lanthanide Separation through Oxidation State Control
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Zhipeng Wang, Jun-Bo Lu, Xue Dong, Qiang Yan, Xiaogui Feng, Han-Shi Hu, Shuao Wang, Jing Chen, Jun Li, and Chao Xu
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Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Catalysis - Abstract
Lanthanide/actinide separation is a worldwide challenge for atomic energy and nuclear waste treatment. Separation of americium (Am), a critical actinide element in the nuclear fuel cycle, from lanthanides (Ln) is highly desirable for minimizing the long-term radiotoxicity of nuclear waste, yet it is extremely challenging given the chemical similarity between trivalent Am(III) and Ln(III). Selective oxidation of Am(III) to a higher oxidation state (OS) could facilitate this separation, but so far, it is far from satisfactory for practical application as a result of the unstable nature of Am in a high OS. Herein, we find a novel strategy to generate stable pentavalent Am (Am(V)) through coordination of Am(III) with a diglycolamide ligand and oxidation with Bi(V) species in the presence of an organic solvent. This strategy leads to efficient stabilization of Am(V) and an extraordinarily high separation factor (10
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- 2022
8. Diradical Generation via Relayed Proton-Coupled Electron Transfer
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Qianqian Shi, Zhipeng Pei, Jinshuai Song, Shi-Jun Li, Donghui Wei, Michelle L. Coote, and Yu Lan
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Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Catalysis - Abstract
Diradical generation followed by radical-radical cross-coupling is a powerful synthetic tool, but its detailed mechanism has yet to be established. Herein, we proposed and confirmed a new model named relayed proton-coupled electron transfer (relayed-PCET) for diradical generation, which could open a door for new radical-radical cross-coupling reactions. Quantum mechanics calculations were performed on a selected carbene-mediated diradical cross-coupling reaction model and a designed model, and the exact electronic structural changes during the radical processes have been observed for the first time.
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- 2022
9. Enantioselective Synthesis of Inherently Chiral Calix[4]arenes via Palladium-Catalyzed Asymmetric Intramolecular C–H Arylations
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Zhang, Yu-Zhen, primary, Xu, Meng-Meng, additional, Si, Xu-Ge, additional, Hou, Jun-Li, additional, and Cai, Quan, additional
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- 2022
- Full Text
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10. Dual Activation Strategy to Achieve C-C Cleavage of Cyclobutanes: Development and Mechanism of Rh and Zn Cocatalyzed [4 + 2] Cycloaddition of Yne-Vinylcyclobutanones
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Guan-Yu Zhang, Pan Zhang, Bing-Wen Li, Kang Liu, Jun Li, and Zhi-Xiang Yu
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Kinetics ,Zinc ,Colloid and Surface Chemistry ,Cycloaddition Reaction ,Molecular Structure ,General Chemistry ,Biochemistry ,Cyclobutanes ,Catalysis - Abstract
Reported here is the Rh and Zn cocatalyzed [4 + 2] cycloaddition of newly designed yne-vinylcyclobutanones, which can generate 5/6 or 6/6 bicyclic products with an all-carbon quaternary bridgehead center. The reaction has a broad scope and can realize chirality transfer from enantioenriched substrates to the cycloadducts. The key to the success of this [4 + 2] reaction is the introduction of a vinyl group to cyclobutanones, which helps the C-C cleavage of vinylcyclobutanones via oxidative addition. This C-C cleavage step is synergistically aided by Zn coordination to the carbonyl group of vinylcyclobutanones. Of the same importance, visual kinetic analysis and computational studies have been carried out to support the dual activation in the rate-determining C-C cleavage, to derive the rate law of the [4 + 2] reaction, to understand another role of Zn in helping the in situ generation of the cationic Rh catalyst and preventing catalyst deactivation, and to analyze the key transition states and intermediates involved.
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- 2022
11. Single Iridium Atom Doped Ni2P Catalyst for Optimal Oxygen Evolution
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Maoyu Wang, Joseph S. Francisco, Shaobo Han, Xiang Huang, Qi Wang, Meng Gu, Hua Zhou, Chao Cai, Zhenxing Feng, Zhe Zhang, Lei Li, Hu Xu, Zhi Liang Zhao, Menghao Li, and Jun Li
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Doping ,Oxygen evolution ,chemistry.chemical_element ,General Chemistry ,Overpotential ,Biochemistry ,Catalysis ,Colloid and Surface Chemistry ,Adsorption ,Chemical engineering ,chemistry ,Desorption ,Iridium ,Current density - Abstract
Single-atom catalysts (SACs) with 100% active sites have excellent prospects for application in the oxygen evolution reaction (OER). However, further enhancement of the catalytic activity for OER is quite challenging, particularly for the development of stable SACs with overpotentials
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- 2021
12. A Multi-Objective Active Learning Platform and Web App for Reaction Optimization
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Jose Antonio Garrido Torres, Sii Hong Lau, Pranay Anchuri, Jason M. Stevens, Jose E. Tabora, Jun Li, Alina Borovika, Ryan P. Adams, and Abigail G. Doyle
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Colloid and Surface Chemistry ,Humans ,Bayes Theorem ,General Chemistry ,Biochemistry ,Mobile Applications ,Catalysis ,Software - Abstract
We report the development of an open-source experimental design via Bayesian optimization platform for multi-objective reaction optimization. Using high-throughput experimentation (HTE) and virtual screening data sets containing high-dimensional continuous and discrete variables, we optimized the performance of the platform by fine-tuning the algorithm components such as reaction encodings, surrogate model parameters, and initialization techniques. Having established the framework, we applied the optimizer to real-world test scenarios for the simultaneous optimization of the reaction yield and enantioselectivity in a Ni/photoredox-catalyzed enantioselective cross-electrophile coupling of styrene oxide with two different aryl iodide substrates. Starting with no previous experimental data, the Bayesian optimizer identified reaction conditions that surpassed the previously human-driven optimization campaigns within 15 and 24 experiments, for each substrate, among 1728 possible configurations available in each optimization. To make the platform more accessible to nonexperts, we developed a graphical user interface (GUI) that can be accessed online through a web-based application and incorporated features such as condition modification on the fly and data visualization. This web application does not require software installation, removing any programming barrier to use the platform, which enables chemists to integrate Bayesian optimization routines into their everyday laboratory practices.
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- 2022
13. Bioinspired Synthesis of Spirochensilide A from Lanosterol
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Xianwen Long, Jun Li, Feng Gao, Hai Wu, and Jun Deng
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Lanosterol ,Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Oxidation-Reduction ,Catalysis ,Triterpenes - Abstract
A bioinspired synthesis of spirochensilide A from commercially available lanosterol is reported. The synthesis features a directed C-H oxidation, a Wagner-Meerwein-type double methyl migration, a Meinwald rearrangement, and a double-bond isomerization/spiroketal formation cascade. The proposed biosynthetic speculation was modified by this synthetic sequence, which also served as a platform for the synthesis of other lanostanes with migrating methyl groups.
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- 2022
14. Rod-Shaped Silver Supercluster Unveiling Strong Electron Coupling between Substituent Icosahedral Units
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Jing-Xuan Zhang, Wen-Di Liu, Shang-Fu Yuan, Cong-Qiao Xu, Quan-Ming Wang, and Jun Li
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Diffraction ,Ligand ,Icosahedral symmetry ,Strong interaction ,Substituent ,General Chemistry ,Electron ,Biochemistry ,Catalysis ,chemistry.chemical_compound ,Crystallography ,Colloid and Surface Chemistry ,chemistry ,Supercluster ,Cluster (physics) - Abstract
The first linear silver supercluster based on icosahedral Ag13 units has been constructed via bridging of dpa ligands: Ag61(dpa)27(SbF6)4 (Hdpa = dipyridylamine) (Ag61). Single-crystal X-ray diffraction reveals that this rod-shaped cluster consists of four vertex-sharing Ag13 icosahedra in a linear arrangement. This Ag61 cluster represents the longest one-dimensional metal nanocluster with a resolved structure. Unprecedented electron coupling develops between their constituent Ag13 units. Theoretical studies disclose that the stabilities of the two superclusters are dictated by a strong interaction between the Ag13 units as well as the ligand effect of the dpa-Ag motifs. The quantum size effect accounts for the significant enhancement of the metal-related absorptions and the red shift at the near-infrared region as the length of the cluster increases. This work sheds light on the evolution of one-dimensional materials and an understanding of the electronic communication between the constituent clusters.
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- 2021
15. Voltage-Driven Flipping of Zwitterionic Artificial Channels in Lipid Bilayers to Rectify Ion Transport
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Zhan-Ting Li, Jun-Li Hou, Yunxiang Zhang, Yong-Hong Fu, Wenning Wang, Ya-Wei Li, Rongrong Wen, Maohua Yang, and Zhao-Jun Yan
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Physics::Biological Physics ,Ion Transport ,Silver ,Alamethicin ,Molecular Structure ,Chemistry ,Lipid Bilayers ,Electric Conductivity ,Silver Compounds ,General Chemistry ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Biochemistry ,Ion Channels ,Catalysis ,Quantitative Biology::Subcellular Processes ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Chemical physics ,Lipid bilayer ,Ion transporter ,Computer Science::Information Theory ,Voltage ,Communication channel - Abstract
We developed a voltage-sensitive artificial transmembrane channel by mimicking the dipolar structure of natural alamethicin channel. The artificial channel featured a zwitterionic structure and could undergo voltage-driven flipping in the lipid bilayers. Importantly, this flipping of the channel could lead to their directional alignment in the bilayers and rectifying behavior for ion transport.
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- 2021
16. Encoding Fluorescence Anisotropic Barcodes with DNA Frameworks
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Qian Li, Bin Chen, Xiaolei Zuo, Jia-Jun Li, Chunhai Fan, Lei Liu, Qiuling Huang, Lihua Wang, Jianlei Shen, Jiye Shi, and Jiang Li
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chemistry.chemical_classification ,Biomolecule ,Optical Imaging ,Fluorescence Polarization ,DNA ,General Chemistry ,Biochemistry ,Environmental variation ,Fluorescence ,Catalysis ,Mice ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Encoding (memory) ,Tumor Cells, Cultured ,Nucleic acid ,Biophysics ,Animals ,Anisotropy ,Fluorescence anisotropy ,Fluorescent Dyes - Abstract
Fluorescence anisotropy (FA) holds great potential for multiplexed analysis and imaging of biomolecules since it can effectively discriminate fluorophores with overlapping emission spectra. Nevertheless, its susceptibility to environmental variation hampers its widespread applications in biology and biotechnology. In this study, we design FA DNA frameworks (FAFs) by scaffolding fluorophores in a fluorescent protein-like microenvironment. We find that the FA stability of the fluorophores is remarkably improved due to the sequestration effects of FAFs. The FA level of the fluorophores can be finely tuned when placed at different locations on an FAF, analogous to spectral shifts of protein-bound fluorophores. The high programmability of FAFs further enables the design of a spectrum of encoded FA barcodes for multiplexed sensing of nucleic acids and multiplexed labeling of live cells. This FAF system thus establishes a new paradigm for designing multiplexing FA probes for cellular imaging and other biological applications.
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- 2021
17. Identifying the Real Chemistry of the Synthesis and Reversible Transformation of AuCd Bimetallic Clusters
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Huixin Xiang, Hao Yan, Jiaohu Liu, Ranran Cheng, Cong-Qiao Xu, Jun Li, and Chuanhao Yao
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Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Catalysis - Abstract
The capability of precisely constructing bimetallic clusters with atomic accuracy provides exciting opportunities for establishing their structure-property correlations. However, the chemistry (the charge state of precursors, the property of ligands, the amount of dopant, and so forth) dictating the fabrication of clusters with atomic-level control has been a long-standing challenge. Herein, based on the well-defined Au
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- 2022
18. Interfacial Engineering of Bi19Br3S27 Nanowires Promotes Metallic Photocatalytic CO2 Reduction Activity under Near-Infrared Light Irradiation
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Jun Li, Xuezhen Feng, Hong Chen, Zhijie Chen, Wenfeng Pan, Qiaoyun Liu, and Zhiquan Chen
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Range (particle radiation) ,Nanowire ,Radiant energy ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,010402 general chemistry ,Solar fuel ,01 natural sciences ,Biochemistry ,Atomic units ,Catalysis ,0104 chemical sciences ,Colloid and Surface Chemistry ,chemistry ,Photocatalysis ,Irradiation ,Carbon - Abstract
Developing highly efficient photocatalysts to utilize solar radiation for converting CO2 into solar fuels is of great importance for energy sustainability and carbon neutralization. Herein, through an alkali-etching-introduced interface reconstruction strategy, a nanowire photocatalyst denoted as V-Bi19Br3S27, with rich Br and S dual-vacancies and surface Bi-O bonding introduced significant near-infrared (NIR) light response, has been developed. The as-obtained V-Bi19Br3S27 nanowires exhibit a highly efficient metallic photocatalytic reduction property for converting CO2 into CH3OH when excited solely under NIR light irradiation. Free of any cocatalyst and sacrificial agent, metallic defective V-Bi19Br3S27 shows 2.3-fold higher CH3OH generation than Bi19Br3S27 nanowires. The detailed interfacial structure evolution and reaction mechanism have been carefully illustrated down to the atomic scale. This work provides a unique interfacial engineering strategy for developing high-performance sulfur-based NIR photocatalysts for photon reducing CO2 into alcohol for achieving high-value solar fuel chemicals, which paves the way for efficiently using the solar radiation energy extending to the NIR range to achieve the carbon neutralization goal.
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- 2021
19. SO
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Ziyi, Li, Jun, Li, Huazhen, Rong, Jiayu, Zuo, Xiong, Yang, Yi, Xing, Yingshu, Liu, Guangshan, Zhu, and Xiaoqin, Zou
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The molecular state is crucial for precise gas separation using a zeolite membrane, yet the state control remains a big challenge. Herein, we report a NO
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- 2022
20. Few-Atom Pt Ensembles Enable Efficient Catalytic Cyclohexane Dehydrogenation for Hydrogen Production
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Yuchen Deng, Yu Guo, Zhimin Jia, Jin-Cheng Liu, Jinqiu Guo, Xiangbin Cai, Chunyang Dong, Meng Wang, Chengyu Li, Jiangyong Diao, Zheng Jiang, Jinglin Xie, Ning Wang, Hai Xiao, Bingjun Xu, Hongbo Zhang, Hongyang Liu, Jun Li, and Ding Ma
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Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Catalysis - Abstract
Identification of catalytic active sites is pivotal in the design of highly effective heterogeneous metal catalysts, especially for structure-sensitive reactions. Downsizing the dimension of the metal species on the catalyst increases the dispersion, which is maximized when the metal exists as single atoms, namely, single-atom catalysts (SACs). SACs have been reported to be efficient for various catalytic reactions. We show here that the Pt SACs, although with the highest metal atom utilization efficiency, are totally inactive in the cyclohexane (C
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- 2022
21. 4CzIPN-tBu-Catalyzed Proton-Coupled Electron Transfer for Photosynthesis of Phosphorylated N-Heteroaromatics
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Xiaolan Chen, Lingbo Qu, Shan-Shan Zhu, Xiao-Yun Li, Bing Yu, Yan Liu, Song Yan, and Shi-Jun Li
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Range (particle radiation) ,Chemistry ,Radical ,General Chemistry ,010402 general chemistry ,Photosynthesis ,Photochemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Electron transfer ,Colloid and Surface Chemistry ,Photocatalysis ,Phosphorylation ,Proton-coupled electron transfer - Abstract
2,4,5,6-Tetrakis(3,6-di-tert-butyl-9H-carbazol-9-yl)isophthalonitrile (4CzIPN-tBu) was developed as a photocatalyst for the phosphorus-radical-initiated cascade cyclization reaction of isocyanides. By using 4CzIPN-tBu as catalyst, we developed a visible-light-induced proton-coupled electron transfer strategy for the generation of phosphorus-centered radicals, via which a wide range of phosphorylated phenanthridines, quinolines, and benzothiazoles were successfully constructed.
- Published
- 2020
22. Artificial Aquaporin That Restores Wound Healing of Impaired Cells
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Zhao-Jun Yan, Zhongju Ye, Gang Wu, Dongdong Wang, Jun-Li Hou, Tonghui Ma, Ting Fan, Zhan-Ting Li, Lehui Xiao, Lu Yang, Yunfeng Wang, Binxiao Li, Chaoqing Dong, Liyun Deng, Wenning Wang, and Jianwei Liu
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Models, Molecular ,Wound Healing ,Molecular Structure ,urogenital system ,Chemistry ,Aquaporin ,Hep G2 Cells ,General Chemistry ,Molecular Dynamics Simulation ,Aquaporins ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Single Molecule Imaging ,Catalysis ,0104 chemical sciences ,Cell biology ,Structure and function ,Colloid and Surface Chemistry ,Membrane ,Human Umbilical Vein Endothelial Cells ,Humans ,Wound healing ,Alternative strategy - Abstract
Artificial aquaporins are synthetic molecules that mimic the structure and function of natural aquaporins (AQPs) in cell membranes. The development of artificial aquaporins would provide an alternative strategy for treatment of AQP-related diseases. In this report, an artificial aquaporin has been constructed from an amino-terminated tubular molecule, which operates in a unimolecular mechanism. The artificial channel can work in cell membranes with high water permeability and selectivity rivaling those of AQPs. Importantly, the channel can restore wound healing of the cells that contain function-lost AQPs.
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- 2020
23. Ultrahigh-Loading of Ir Single Atoms on NiO Matrix to Dramatically Enhance Oxygen Evolution Reaction
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Maoyu Wang, Qi Wang, Hu Xu, Zhenxing Feng, Jun Li, Meng Gu, Xiang Huang, Zhi Liang Zhao, and Bin Xiang
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Chemistry ,Nickel oxide ,Non-blocking I/O ,Oxygen evolution ,General Chemistry ,Overpotential ,010402 general chemistry ,Electrocatalyst ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Colloid and Surface Chemistry ,Chemical engineering ,Oxidation state ,Density functional theory - Abstract
Engineering single-atom electrocatalysts with high-loading amount holds great promise in energy conversion and storage application. Herein, we report a facile and economical approach to achieve an unprecedented high loading of single Ir atoms, up to ∼18wt%, on the nickel oxide (NiO) matrix as the electrocatalyst for oxygen evolution reaction (OER). It exhibits an overpotential of 215 mV at 10 mA cm-2 and a remarkable OER current density in alkaline electrolyte, surpassing NiO and IrO2 by 57 times and 46 times at 1.49 V vs RHE, respectively. Systematic characterizations, including X-ray absorption spectroscopy and aberration-corrected Z-contrast imaging, demonstrate that the Ir atoms are atomically dispersed at the outermost surface of NiO and are stabilized by covalent Ir-O bonding, which induces the isolated Ir atoms to form a favorable ∼4+ oxidation state. Density functional theory calculations reveal that the substituted single Ir atom not only serves as the active site for OER but also activates the surface reactivity of NiO, which thus leads to the dramatically improved OER performance. This synthesis method of developing high-loading single-atom catalysts can be extended to other single-atom catalysts and paves the way for industrial applications of single-atom catalysts.
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- 2020
24. Mode Specificity in the OH + HO2 → H2O + O2 Reaction: Enhancement of Reactivity by Exciting a Spectator Mode
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Yang Liu, Hongwei Song, Daiqian Xie, Jun Li, and Hua Guo
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Coupling ,Work (thermodynamics) ,Chemistry ,Mode (statistics) ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Reaction coordinate ,Dipole ,Colloid and Surface Chemistry ,Chemical physics ,Energy flow ,Reactivity (chemistry) ,Excitation - Abstract
A reaction typically involves a few active modes while the other modes are largely preserved throughout the reaction as spectators. Excitation of an active mode is expected to promote the reaction, but depositing energy in a spectator mode typically has no effect, because of the differing ability for energy flow to the reaction coordinate. In this work, we report a surprising case of mode specificity in a key radical-radical reaction OH + HO2 → H2O + O2, where such canonical expectations fail to hold. Despite its spectator nature, the vibrational excitation of the OH reactant is shown at low collision energies to enhance the reactivity significantly. This unique effect can be attributed to the increased attraction with HO2 due to the larger dipole of the stretched OH. At low collision energies, the stronger attraction increases the chance of capturing the reactants to form a hydrogen-bonded complex, thus of passing through the submerged barrier. The novel mechanism differs from the conventional vibrational enhancement via coupling to the reaction coordinate at the transition state, enriching our understanding of mode specificity in chemistry.
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- 2020
25. Constructing High-Loading Single-Atom/Cluster Catalysts via an Electrochemical Potential Window Strategy
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Jun Li, Jin-Cheng Liu, and Hai Xiao
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Graphene ,Chemistry ,Substrate (chemistry) ,General Chemistry ,010402 general chemistry ,Heterogeneous catalysis ,Electrochemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,law.invention ,Colloid and Surface Chemistry ,Chemical engineering ,law ,Cluster (physics) ,Selectivity ,Electrochemical potential - Abstract
Single-atom catalysts (SACs) and single-cluster catalysts (SCCs) are the new frontier of heterogeneous catalysis, which exhibit high activity, selectivity, stability, and atomic efficiency as well as precise tunability. However, the lack of efficient methods for producing high-loading and high-purity SACs and SCCs hinders their industrial applications. In this work, we propose a general and efficient strategy for the production of high-loading and high-purity SACs and SCCs anchored on suitable substrates. Our strategy relies on the existence of an electrochemical potential window (EcPW) we predict within which any aggregate forms of the target metal on the substrate are leached away by electrochemical oxidation, while the strongly bound single atoms or single clusters remain at the substrate. We demonstrate the applicability of this strategy with modeling the production of Pt, Pd, and Ni SACs anchored on N-doped graphene and Fe2O3 as well as Pt3 and Ni3 SCCs anchored on graphdiyne.
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- 2020
26. Capture of the Sulfur Monoxide–Hydroxyl Radical Complex
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Changyun Chen, Xiaofang Zhao, Weiyu Qian, Jie Liu, Xiaoqing Zeng, Joseph S. Francisco, Tarek Trabelsi, Jie Qin, Lina Wang, Bo Lu, and Jun Li
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Sulfur monoxide ,Chemistry ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Biochemistry ,Sulfur ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Laser photolysis ,Atmospheric chemistry ,Hydroxyl radical - Abstract
The elusive hydrogen-bonded sulfur monoxide–hydroxyl radical complex (•OH···OS), a missing intermediate in the atmospheric chemistry of SO2, was generated in the 266 nm laser photolysis of the sulf...
- Published
- 2020
27. All-Solid-State Lithium-Sulfur Batteries Enhanced by Redox Mediators
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Xin Xiao, Xueli Zheng, Yuchi Tsao, Pu Zhang, Yufei Yang, Yi Cui, Yusheng Ye, Jun Li, Xin Gao, Zhenan Bao, and Rong Xu
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Chemistry ,Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,Electrolyte ,Biochemistry ,Sulfur ,Redox ,Catalysis ,Quinone ,Chemical kinetics ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Lithium sulfide ,Faraday efficiency ,Sulfur utilization - Abstract
Redox mediators (RMs) play a vital role in some liquid electrolyte-based electrochemical energy storage systems. However, the concept of redox mediator in solid-state batteries remains unexplored. Here, we selected a group of RM candidates and investigated their behaviors and roles in all-solid-state lithium-sulfur batteries (ASSLSBs). The soluble-type quinone-based RM (AQT) shows the most favorable redox potential and the best redox reversibility that functions well for lithium sulfide (Li2S) oxidation in solid polymer electrolytes. Accordingly, Li2S cathodes with AQT RMs present a significantly reduced energy barrier (average oxidation potential of 2.4 V) during initial charging at 0.1 C at 60 °C and the following discharge capacity of 1133 mAh gs-1. Using operando sulfur K-edge X-ray absorption spectroscopy, we directly tracked the sulfur speciation in ASSLSBs and proved that the solid-polysulfide-solid reaction of Li2S cathodes with RMs facilitated Li2S oxidation. In contrast, for bare Li2S cathodes, the solid-solid Li2S-sulfur direct conversion in the first charge cycle results in a high energy barrier for activation (charge to ∼4 V) and low sulfur utilization. The Li2S@AQT cell demonstrates superior cycling stability (average Coulombic efficiency 98.9% for 150 cycles) and rate capability owing to the effective AQT-enhanced Li-S reaction kinetics. This work reveals the evolution of sulfur species in ASSLSBs and realizes the fast Li-S reaction kinetics by designing an effective sulfur speciation pathway.
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- 2021
28. 2D MOF Periodontitis Photodynamic Ion Therapy
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Lei Tan, Zhaoyang Li, Shengli Zhu, Xingcai Zhang, Xiangmei Liu, Jiashen Meng, Yanqin Liang, Shuang Song, Zhenduo Cui, Shuilin Wu, Yufeng Zheng, Kelvin W.K. Yeung, and Jun Li
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Staphylococcus aureus ,medicine.drug_class ,Antibiotics ,Pharmacology ,medicine.disease_cause ,Biochemistry ,Catalysis ,Colloid and Surface Chemistry ,medicine ,Humans ,Periodontitis ,Porphyromonas gingivalis ,Metal-Organic Frameworks ,chemistry.chemical_classification ,Reactive oxygen species ,Photolysis ,biology ,Fusobacterium nucleatum ,Chemistry ,General Chemistry ,medicine.disease ,biology.organism_classification ,Antimicrobial ,Nanostructures ,Photochemotherapy ,Antibacterial activity - Abstract
Traditional surgical intervention and antibiotic treatment are poor and even invalid for chronic diseases including periodontitis induced by diverse oral pathogens, which often causes progressive destruction of tissues, even tooth loss, and systemic diseases. Herein, an ointment comprising atomic-layer Fe2O3-modified two-dimensional porphyrinic metal-organic framework (2D MOF) nanosheets is designed by incorporating a polyethylene glycol matrix. After the atomic layer deposition surface engineering, the enhanced photocatalytic activity of the 2D MOF heterointerface results from lower adsorption energy and more charge transfer amounts due to the synergistic effect of metal-linker bridging units, abundant active sites, and an excellent light-harvesting network. This biocompatible and biodegradable 2D MOF-based heterostructure exhibits broad-spectrum antimicrobial activity (99.87 ± 0.09%, 99.57 ± 0.21%, and 99.03 ± 0.24%) against diverse oral pathogens (Porphyromonas gingivalis, Fusobacterium nucleatum, and Staphylococcus aureus) by the synergistic effect of reactive oxygen species and released ions. This photodynamic ion therapy exhibits a superior therapeutic effect to the reported clinical periodontitis treatment owing to rapid antibacterial activity, alleviative inflammation, and improved angiogenesis.
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- 2021
29. Single Iridium Atom Doped Ni
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Qi, Wang, Zhe, Zhang, Chao, Cai, Maoyu, Wang, Zhi Liang, Zhao, Menghao, Li, Xiang, Huang, Shaobo, Han, Hua, Zhou, Zhenxing, Feng, Lei, Li, Jun, Li, Hu, Xu, Joseph S, Francisco, and Meng, Gu
- Abstract
Single-atom catalysts (SACs) with 100% active sites have excellent prospects for application in the oxygen evolution reaction (OER). However, further enhancement of the catalytic activity for OER is quite challenging, particularly for the development of stable SACs with overpotentials180 mV. Here, we report an iridium single atom on Ni
- Published
- 2021
30. Electrostatic Interactions Accelerating Water Oxidation Catalysis via Intercatalyst O-O Coupling
- Author
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Jun Li, Qiang Tian, Ning Wang, Lin Chen, Shaoqi Zhan, Wen-Hua Xu, Biaobiao Zhang, Mårten S. G. Ahlquist, and Jiajia Yi
- Subjects
Chemistry ,Intermolecular force ,General Chemistry ,Antiparallel (biochemistry) ,Electrostatics ,Biochemistry ,Small molecule ,Catalysis ,Coupling (electronics) ,Molecular dynamics ,Colloid and Surface Chemistry ,Chemical physics ,Molecule - Abstract
Intercatalyst coupling has been widely applied in the functional mimics for binuclear synergy in natural metal enzymes. Herein, we introduce two facile and effective design strategies, which facilitate the coupling of two catalytic units via electrostatic interactions. The first system is based on a catalyst molecule functionalized with both a positively charged and a negatively charged group in the structure being able to pair with each other in an antiparallel manner arranged by electrostatic interactions. The other system consists of a mixture of two different of catalysts modified with either positively or negatively charged groups to generate intermolecular electrostatic interactions. Applying these designs to Ru(bda) (H2bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) water-oxidation catalysts improved the catalytic performance by more than an order of magnitude. The intermolecular electrostatic interactions in these two systems were fully identified by 1H NMR, TEM, SAXS, and electrical conductivity experiments. Molecular dynamics simulations further verified that electrostatic interactions contribute to the formation of prereactive dimers, which were found to play a key role in dramatically improving the catalytic performance. The successful strategies demonstrated here can be used in designing other intercatalyst coupling systems for activation and formation of small molecules and organic synthesis.
- Published
- 2021
31. Voltage-Driven Flipping of Zwitterionic Artificial Channels in Lipid Bilayers to Rectify Ion Transport
- Author
-
Yan, Zhao-Jun, primary, Li, Ya-Wei, additional, Yang, Maohua, additional, Fu, Yong-Hong, additional, Wen, Rongrong, additional, Wang, Wenning, additional, Li, Zhan-Ting, additional, Zhang, Yunxiang, additional, and Hou, Jun-Li, additional
- Published
- 2021
- Full Text
- View/download PDF
32. Construction of Dopamine-Releasing Gold Surfaces Mimicking Presynaptic Membrane by On-Chip Electrochemistry
- Author
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Chuanguang Qin, Hao-Li Zhang, An Pengrong, Jinghong Sun, Xiaoyan Liu, Jun Li, Ruihua Dong, Xingyu Jiang, Xingyu Zhang, Yanbo Xie, Wenfu Zheng, and Chun-Lin Sun
- Subjects
Surface Properties ,Dopamine ,Microfluidics ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Biochemistry ,Catalysis ,Colloid and Surface Chemistry ,Biomimetics ,Monolayer ,medicine ,Electrodes ,Chemistry ,Cell Membrane ,General Chemistry ,0104 chemical sciences ,Membrane ,Polymerization ,Electrode ,Solvents ,Biophysics ,Gold ,Imines ,Gold surface ,medicine.drug - Abstract
We report a strategy to construct a dopamine-releasing gold surface mimicking a presynaptic membrane on a microfluidic chip to simulate in vivo neural signaling. We constructed dopamine self-assembled monolayers (DA SAMs) by electrochemical deprotection of methyl group-protected DA SAMs on a gold surface. Electrochemically controllable release of DA SAMs can be realized by applying nonhydrolytic negative potential on the gold surface. Our method in constructing DA SAMs avoids the polymerization and protonation of DA molecules which may lead to the failure of the DA SAM formation. By combining microfluidics, we realized spatial and temporal controllable release of DA by electrochemistry from the gold surface. Furthermore, by culturing neurons on the patterned DA SAMs, the interface between the DA SAMs and the neurons could serve as a presynaptic membrane, and the spatiotemporal release of DA could modulate the neuron activity with high precision. Our study holds great promise in the fields of neurobiology research and drug screening.
- Published
- 2019
33. Binding Site Diversity Promotes CO2 Electroreduction to Ethanol
- Author
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Fengwang Li, David Sinton, Joshua Wicks, Mingchuan Luo, Tiange Yuan, F. Pelayo García de Arquer, Ying Wang, Cao-Thang Dinh, Yuguang C. Li, Jun Li, Ziyun Wang, Bin Chen, Dae-Hyun Nam, Oleksandr Voznyy, and Edward H. Sargent
- Subjects
Ethanol ,Ethylene ,General Chemistry ,Reaction intermediate ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,7. Clean energy ,Biochemistry ,Combinatorial chemistry ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Ethanol fuel ,Selectivity ,Bimetallic strip - Abstract
The electrochemical reduction of CO2 has seen many record-setting advances in C2 productivity in recent years. However, the selectivity for ethanol, a globally significant commodity chemical, is still low compared to the selectivity for products such as ethylene. Here we introduce diverse binding sites to a Cu catalyst, an approach that destabilizes the ethylene reaction intermediates and thereby promotes ethanol production. We develop a bimetallic Ag/Cu catalyst that implements the proposed design toward an improved ethanol catalyst. It achieves a record Faradaic efficiency of 41% toward ethanol at 250 mA/cm2 and -0.67 V vs RHE, leading to a cathodic-side (half-cell) energy efficiency of 24.7%. The new catalysts exhibit an in situ Raman spectrum, in the region associated with CO stretching, that is much broader than that of pure Cu controls, a finding we account for via the diversity of binding configurations. This physical picture, involving multisite binding, accounts for the enhanced ethanol production for bimetallic catalysts, and presents a framework to design multimetallic catalysts to control reaction paths in CO2 reductions toward desired products.
- Published
- 2019
34. Photocatalytic CO2 Conversion of M0.33WO3 Directly from the Air with High Selectivity: Insight into Full Spectrum-Induced Reaction Mechanism
- Author
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Yuan Li, Jun Li, Yi Xie, Gaoke Zhang, Xiaoyong Wu, Yongfu Sun, Hong Chen, Yan Zhao, Kai Wang, and Yang Pan
- Subjects
Reaction mechanism ,Atmospheric pressure ,Chemistry ,chemistry.chemical_element ,General Chemistry ,Tungsten ,010402 general chemistry ,Alkali metal ,Photochemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Artificial photosynthesis ,Colloid and Surface Chemistry ,Photocatalysis ,Selectivity ,Ambient pressure - Abstract
Natural photosynthesis is a solar light-driven process utilized by plants to convert CO2 and water into carbohydrate molecules. The goal of artificial photosynthesis is the reduction of CO2 directly from air into high purity value-added products at atmospheric pressure. However, its realization, combined with deep mechanism investigation, is a huge challenge. Herein, we demonstrate that hexagonal tungsten bronze M0.33WO3 (M = K, Rb, Cs) series with {010} facets, prepared by a peculiar “water-controllable releasing” solvothermal method, showed excellent full spectrum (UV, visible, and NIR lights)-induced photocatalytic CO2 reduction performance directly from the air at ambient pressure. Particularly, after 4 h near-infrared light irradiation, ca. 4.32% CO2 in the air could be converted into CH3OH with 98.35% selectivity for Rb0.33WO3. The experiments and theoretical calculations unveiled that the introduced alkali metal atom occupied the tunnel of hexagonal structure and donated more free electrons to reco...
- Published
- 2019
35. Constructing NiCo/Fe3O4 Heteroparticles within MOF-74 for Efficient Oxygen Evolution Reactions
- Author
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Zhi Li, Jun Li, Yue Gong, Yadong Li, Shoujie Liu, Qing Peng, Dingsheng Wang, Qinghua Zhang, Youqi Zhu, Lin Gu, Chen Chen, Xiaolu Wang, Xiaodong Han, Lirong Zheng, Hai Xiao, and Ang Li
- Subjects
Tafel equation ,Nanostructure ,Chemistry ,Oxygen evolution ,Nanoparticle ,02 engineering and technology ,General Chemistry ,Overpotential ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Metal ,Colloid and Surface Chemistry ,Chemical engineering ,visual_art ,visual_art.visual_art_medium ,Density functional theory ,0210 nano-technology ,Pyrolysis - Abstract
Metal–organic frameworks (MOF) have recently emerged as versatile precursors to fabricate functional MOF derivatives for oxygen evolution reactions (OER). Herein, we developed a controlled partial pyrolysis strategy to construct robust NiCo/Fe3O4 heteroparticles within MOF-74 for efficient OER using trimetallic NiCoFe-MOF-74 as precursor. The partial pyrolysis method preserves the framework structure of MOF for effective substrates diffusion while producing highly active nanoparticles. The as-prepared NiCo/Fe3O4/MOF-74 delivered remarkably stable OER current with an overpotential as low as 238 mV at 10.0 mA cm–2 and an Tafel slop of 29 mV/dec, outperforming those of pristine NiCoFe-MOF-74, totally decomposed MOF derivatives, and most reported non-noble metal based electrocatalysts. The key for the formation of NiCo/Fe3O4/MOF-74 nanostructures is that the metals can be decomposed from NiCoFe-MOF-74 in the order of Ni, Co, and Fe under controlled heat treatment. Density functional theory calculations reveal...
- Published
- 2018
36. Measurement and Manipulation of the Charge State of an Adsorbed Oxygen Adatom on the Rutile TiO2(110)-1×1 Surface by nc-AFM and KPFM
- Author
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Ján Brndiar, Yasuhiro Sugawara, Masato Miyazaki, Rui Xu, Huan Fei Wen, Ivan Štich, Quanzhen Zhang, Yuuki Adachi, Zhihai Cheng, Lev Kantorovich, and Yan Jun Li
- Subjects
Kelvin probe force microscope ,Chemistry ,Charge (physics) ,02 engineering and technology ,General Chemistry ,Electron ,021001 nanoscience & nanotechnology ,01 natural sciences ,Biochemistry ,Molecular physics ,Catalysis ,Colloid and Surface Chemistry ,Atomic orbital ,Electric field ,0103 physical sciences ,Atom ,Density functional theory ,010306 general physics ,0210 nano-technology ,Volta potential - Abstract
For the first time, the charge states of adsorbed oxygen adatoms on the rutile TiO2(110)-1×1 surface are successfully measured and deliberately manipulated by a combination of noncontact atomic force microscopy and Kelvin probe force microscopy at 78 K under ultrahigh vacuum and interpreted by extensive density functional theory modeling. Several kinds of single and double oxygen adatom species are clearly distinguished and assigned to three different charge states: Oad-/2Oad-, Oad2-/2Oad2-, and Oad--Oad2-, i.e., formal charges of either one or two electrons per atom. Because of the strong atomic-scale image contrast, these states are clearly resolved. The observations are supported by measurements of the short-range force and local contact potential difference as a function of the tip-sample distance as well as simulations. Comparison with the simulations suggests subatomic resolution by allowing us to resolve the rotated oxygen p orbitals. In addition, we manage to reversibly switch the charge states of the oxygen adatoms between the Oad- and Oad2- states, both individually and next to another oxygen, by modulating the frequency shift at constant positive voltage during both charging and discharging processes, i.e., by the tip-induced electric field of one orientation. This work provides a novel route for the investigation of the charge state of the adsorbates and opens up novel prospects for studying transition-metal-oxide-based catalytic reactions.
- Published
- 2018
37. Metal–Organic Frameworks Mediate Cu Coordination for Selective CO2 Electroreduction
- Author
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Petar Todorović, Dae-Hyun Nam, Jun Li, Andrew H. Proppe, Oleksandr S. Bushuyev, Osama Shekhah, Yuhang Wang, Phil De Luna, Jea Woong Jo, Se-Woong Baek, Mohamed Eddaoudi, Cao-Thang Dinh, Edward H. Sargent, Shana O. Kelley, Jongmin Choi, Chih Shan Tan, Min-Jae Choi, David Sinton, Junghwan Kim, Ali Seifitokaldani, Christine M. Gabardo, F. Pelayo García de Arquer, and Zhiqin Liang
- Subjects
Dimer ,Coordination number ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Biochemistry ,Tricarboxylate ,Catalysis ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,Crystallography ,Colloid and Surface Chemistry ,chemistry ,law ,Oxidation state ,Metal-organic framework ,0210 nano-technology ,Selectivity ,Electron paramagnetic resonance ,Electrochemical reduction of carbon dioxide - Abstract
The electrochemical carbon dioxide reduction reaction (CO2RR) produces diverse chemical species. Cu clusters with a judiciously controlled surface coordination number (CN) provide active sites that simultaneously optimize selectivity, activity, and efficiency for CO2RR. Here we report a strategy involving metal–organic framework (MOF)-regulated Cu cluster formation that shifts CO2 electroreduction toward multiple-carbon product generation. Specifically, we promoted undercoordinated sites during the formation of Cu clusters by controlling the structure of the Cu dimer, the precursor for Cu clusters. We distorted the symmetric paddle-wheel Cu dimer secondary building block of HKUST-1 to an asymmetric motif by separating adjacent benzene tricarboxylate moieties using thermal treatment. By varying materials processing conditions, we modulated the asymmetric local atomic structure, oxidation state and bonding strain of Cu dimers. Using electron paramagnetic resonance (EPR) and in situ X-ray absorption spectros...
- Published
- 2018
38. Introducing the Dihydro-1,3-azaboroles: Convenient Entry by a Three-Component Reaction, Synthetic and Photophysical Application
- Author
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Gustavo Fernández, Constantin G. Daniliuc, Gerhard Erker, Kalathil K. Kartha, Gerald Kehr, and Jun Li
- Subjects
Ligand ,Component (thermodynamics) ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Combinatorial chemistry ,Fluorescence ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Deprotonation ,Acetylene ,chemistry ,Reagent ,Organometallic chemistry - Abstract
The (Fmes)BH2·SMe2 reagent (7) reacts sequentially with an acetylene and, e.g., xylylisonitrile in a convenient three-component reaction to give a series of unprecedented dihydro-1,3-azaborole derivatives 16. The tolane-derived example 16a was deprotonated and used as a ligand in organometallic chemistry. Compounds 16 served as the starting materials for the straightforward synthesis of various dihydro-1,3-azaborinine derivatives by treatment with an isonitrile. Several diaryldihydro-1,3-azaboroles showed interesting photophysical properties such as aggregation-induced emission and high fluorescence quantum yields.
- Published
- 2021
39. 4CzIPN
- Author
-
Yan, Liu, Xiao-Lan, Chen, Xiao-Yun, Li, Shan-Shan, Zhu, Shi-Jun, Li, Yan, Song, Ling-Bo, Qu, and Bing, Yu
- Subjects
Electron Transport ,Molecular Structure ,Heterocyclic Compounds ,Phosphorylation ,Protons ,Hydrocarbons, Aromatic ,Catalysis - Abstract
2,4,5,6-Tetrakis(3,6-di
- Published
- 2020
40. Metal-Free Direct Deoxygenative Borylation of Aldehydes and Ketones
- Author
-
Zihang Qiu, Jianbin Li, Chao-Jun Li, Haining Wang, and Chia-Yu Huang
- Subjects
chemistry.chemical_classification ,Colloid and Surface Chemistry ,Ketone ,Metal free ,Chemistry ,Organic chemistry ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Borylation ,Catalysis ,0104 chemical sciences - Abstract
Direct conversion of aldehydes and ketones into alkylboronic esters via deoxygenative borylation represents an unknown yet highly desirable transformation. Herein, we present a one-step and metal-free method for carbonyl deoxy-borylation under mild conditions. A wide range of aromatic aldehydes and ketones are tolerated and successfully converted into the corresponding benzylboronates. By the same deoxygenation manifold with aliphatic aldehydes and ketones, we also enable a concise synthesis of 1,1,2-tris(boronates), a family of compounds that currently lack efficient synthetic methods. Given its simplicity and versatility, we expect that this novel borylation approach could show great promise in organoboron synthesis and inspire more carbonyl deoxygenative transformations in both academic and industrial settings.
- Published
- 2020
41. 2-Butene Tetraanion Bridged Dinuclear Samarium(III) Complexes via Sm(II)-Mediated Reduction of Electron-Rich Olefins
- Author
-
Han-Shi Hu, Zhe Huang, Botao Wu, Yu Zheng, Jun Li, Wangyang Ma, Tianyang Chen, Wen-Xiong Zhang, Jianhao Yin, Zhenfeng Xi, Chao Yu, and Changsu Cao
- Subjects
Ligand ,chemistry.chemical_element ,General Chemistry ,Conjugated system ,010402 general chemistry ,Metathesis ,Antibonding molecular orbital ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Samarium ,Cyclooctatetraene ,chemistry.chemical_compound ,Crystallography ,Colloid and Surface Chemistry ,chemistry ,Density functional theory ,Reactivity (chemistry) - Abstract
While reduction reactions are ubiquitous in chemistry, it is very challenging to further reduce electron-rich compounds, especially the anionic ones. In this work, the reduction of 1,3-butadienyl dianion, the anionic conjugated olefin, has been realized by divalent rare-earth metal compounds (SmI2), resulting in the formation of novel 2-butene tetraanion bridged disamarium(III) complexes. Density functional theory (DFT) analyses reveal two features: (i) the single electron transfer (SET) from 4f atomic orbitals (AOs) of each Sm center to the antibonding π*-orbitals of 1,3-butadienyl dianion is feasible and the new HOMO formed by the bonding interaction between Sm 5d orbitals (AOs) and the π*-orbitals of 1,3-butadienyl dianion can accept favorably 2e- from 4f AOs of Sm(II); (ii) the 2-butene tetraanionic ligand serves as a unique 10e- donating system, in which 4e- act as two σ-donation bonding interactions while the rest 6e- as three π-donation bonding interactions. The disamarium(III) complexes represent a unique class of the bridged bis-alkylidene rare-earth organometallic complexes. The ligand-based reductive reactivity of 2-butene tetraanion bridged disamarium(III) complexes demonstrates that 2-butene tetraanionic ligand serves as a 3e- reductant toward cyclooctatetraene (COT) to provide doubly COT-supported disamarabutadiene complexes. The reaction of the disamarium(III) complexes with Cp*Li produces the doubly Cp*-coordinated Sm(III) complexes via salt metathesis. In addition, the reaction with Mo(CO)6 affords the oxycyclopentadienyl dinuclear complex via CO insertion.
- Published
- 2020
42. Enhanced Nitrate-to-Ammonia Activity on Copper-Nickel Alloys via Tuning of Intermediate Adsorption
- Author
-
David Sinton, Ziyun Wang, Dae-Hyun Nam, Jun Li, Yu Ding, Aoni Xu, Fengwang Li, Cao-Thang Dinh, Jiawen Wu, Yuhang Wang, Joshua Wicks, Yanwei Lum, Mingchuan Luo, Chih Shan Tan, Linsong Huang, Gengfeng Zheng, and Edward H. Sargent
- Subjects
Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Biochemistry ,Copper ,Redox ,Catalysis ,0104 chemical sciences ,Ammonia ,chemistry.chemical_compound ,Nickel ,Colloid and Surface Chemistry ,Adsorption ,chemistry ,Reversible hydrogen electrode - Abstract
Electrochemical conversion of nitrate (NO3-) into ammonia (NH3) recycles nitrogen and offers a route to the production of NH3, which is more valuable than dinitrogen gas. However, today's development of NO3- electroreduction remains hindered by the lack of a mechanistic picture of how catalyst structure may be tuned to enhance catalytic activity. Here we demonstrate enhanced NO3- reduction reaction (NO3-RR) performance on Cu50Ni50 alloy catalysts, including a 0.12 V upshift in the half-wave potential and a 6-fold increase in activity compared to those obtained with pure Cu at 0 V vs reversible hydrogen electrode (RHE). Ni alloying enables tuning of the Cu d-band center and modulates the adsorption energies of intermediates such as *NO3-, *NO2, and *NH2. Using density functional theory calculations, we identify a NO3-RR-to-NH3 pathway and offer an adsorption energy-activity relationship for the CuNi alloy system. This correlation between catalyst electronic structure and NO3-RR activity offers a design platform for further development of NO3-RR catalysts.
- Published
- 2020
43. Crown Ether Modulation Enables over 23% Efficient Formamidinium-Based Perovskite Solar Cells
- Author
-
Michael A. Hope, Anurag Krishna, Mounir Mensi, Hong Zhang, Farzaneh Jahanbakhshi, Marko Mladenović, Ursula Rothlisberger, Felix Eickemeyer, Dan Ren, Lyndon Emsley, Shaik M. Zakeeruddin, Tzu-Sen Su, Aditya Mishra, Kevin Sivula, Olivier Ouellette, Hsin-Hsiang Huang, Anders Hagfeldt, Tzu-Chien Wei, Jun Li, Hua Zhou, Zhiwen Zhou, Michael Grätzel, Jovana V. Milić, and Jun-Ho Yum
- Subjects
chemistry.chemical_classification ,Passivation ,Chemistry ,business.industry ,Photovoltaic system ,Supramolecular chemistry ,General Chemistry ,010402 general chemistry ,7. Clean energy ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Colloid and Surface Chemistry ,Formamidinium ,Optoelectronics ,Grain boundary ,Density functional theory ,business ,Crown ether ,Perovskite (structure) - Abstract
The use of molecular modulators to reduce the defect density at the surface and grain boundaries of perovskite materials has been demonstrated to be an effective approach to enhance the photovoltaic performance and device stability of perovskite solar cells. Herein, we employ crown ethers to modulate perovskite films, affording passivation of undercoordinated surface defects. This interaction has been elucidated by solid-state nuclear magnetic resonance and density functional theory calculations. The crown ether hosts induce the formation of host-guest complexes on the surface of the perovskite films, which reduces the concentration of surface electronic defects and suppresses nonradiative recombination by 40%, while minimizing moisture permeation. As a result, we achieved substantially improved photovoltaic performance with power conversion efficiencies exceeding 23%, accompanied by enhanced stability under ambient and operational conditions. This work opens a new avenue to improve the performance and stability of perovskite-based optoelectronic devices through supramolecular chemistry.
- Published
- 2020
- Full Text
- View/download PDF
44. Design of Single-Atom Co–N5 Catalytic Site: A Robust Electrocatalyst for CO2 Reduction with Nearly 100% CO Selectivity and Remarkable Stability
- Author
-
Qing Peng, Yuan Pan, Wei Zhu, Weng-Chon Cheong, Dingsheng Wang, Yinjuan Chen, Rui Lin, Yadong Li, Xing Cao, Wenxing Chen, Konglin Wu, Yu Wang, Xin Chen, Jun Li, Shoujie Liu, Yan Lin, Lirong Zheng, Chenguang Liu, Qi Lu, Chen Chen, Yunqi Liu, and Jun Luo
- Subjects
Chemistry ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrocatalyst ,01 natural sciences ,Biochemistry ,Redox ,Catalysis ,0104 chemical sciences ,Active center ,Colloid and Surface Chemistry ,Chemical engineering ,Desorption ,Density functional theory ,0210 nano-technology ,Selectivity ,Faraday efficiency - Abstract
We develop an N-coordination strategy to design a robust CO2 reduction reaction (CO2RR) electrocatalyst with atomically dispersed Co–N5 site anchored on polymer-derived hollow N-doped porous carbon spheres. Our catalyst exhibits high selectivity for CO2RR with CO Faradaic efficiency (FECO) above 90% over a wide potential range from −0.57 to −0.88 V (the FECO exceeded 99% at −0.73 and −0.79 V). The CO current density and FECO remained nearly unchanged after electrolyzing 10 h, revealing remarkable stability. Experiments and density functional theory calculations demonstrate single-atom Co–N5 site is the dominating active center simultaneously for CO2 activation, the rapid formation of key intermediate COOH* as well as the desorption of CO.
- Published
- 2018
45. Enzyme catalysis: Tool to make and break amygdalin hydrogelators from renewable resources: A delivery model for hydrophobic drugs
- Author
-
Vemula, Praveen Kumar, John, George, and Jun Li
- Subjects
Hydrophobic effect -- Analysis ,Catalysis -- Analysis ,Anti-inflammatory drugs -- Chemical properties ,Decomposition (Chemistry) -- Analysis ,Chemistry - Abstract
A novel approach for the controlled delivery of an anti-inflammatory, chemopreventive drug by an enzyme-triggered drug release mechanism through the degradation of encapsulated hydrogels is reported. The hydro-and organogelators are synthesized in high yields from renewable resources by using regioselective enzyme catalysis.
- Published
- 2006
46. Surface Single-Cluster Catalyst for N2-to-NH3 Thermal Conversion
- Author
-
Hai Xiao, Xuelu Ma, Jun Li, and Jin-Cheng Liu
- Subjects
Doping ,Oxide ,02 engineering and technology ,General Chemistry ,Associative substitution ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Metal ,Ammonia production ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Chemical engineering ,visual_art ,Atom ,visual_art.visual_art_medium ,0210 nano-technology ,Bimetallic strip - Abstract
The ammonia synthesis from N2 is of vital importance, with imitating biological nitrogen fixation attracted much interest. Herein, we investigate the catalytic mechanisms of N2-to-NH3 thermal conversion on the singly dispersed bimetallic catalyst Rh1Co3/CoO(011), and find that the preferred pathway is an associative mechanism analogous to the biological process, in which alternating hydrogenations of the N2 occur, with H2 activation on both metal sites. We propose that the singly dispersed bimetallic M1An catalyst, in which the doped metal atom M substitutes an oxygen atom on the oxide surface of metal A, serves as a new surface single-cluster catalyst (SCC) design platform for the biomimetic N2-to-NH3 thermal conversion. The catalytic ability of M1An catalyst is attributed to both the charge buffer capacity of doped metal M and the complementary role of synergic metal A in catalysis. Our work provides insights and guidelines for further optimizing the M1An catalyst.
- Published
- 2017
47. Hydrogen-bonding-driven preorganized zinc porphyrin receptors for efficient complexation of C60, C70, and C60 derivatives
- Author
-
Xi-Kui Jiang, Zong-Quan Wu, Xue-Bin Shao, Zhan-Ting Li, Chuang Li, Jun-Li Hou, and Kui Wang
- Subjects
Buckminsterfullerene -- Chemical properties ,Porphyrins -- Chemical properties ,Zinc compounds -- Chemical properties ,Hydrogen bonding -- Structure ,Chemistry - Abstract
The self-assembly of molecular tweezers whose rigid skeletons are constructed based on the intramolecular hydrogen-bonding driven aromatic amide foldamers is described. The zinc porphyrin-based, well-ordered tweezers are efficient nonring receptors for complexation of fullerene and fullerene derived molecules like C60, C70 and C60 derivatives, due to their preorganized rigid conformation.
- Published
- 2005
48. Unique Co chemisorption properties of gold hexamer: Au6(CO)(sub n)-(n=0-3)
- Author
-
Hua-Jin Zhai, Kiran, Boggavarapu, Dai, Bing, Jun Li, and Lai-Sheng Wang
- Subjects
Gold compounds -- Chemical properties ,Photoelectron spectroscopy -- Usage ,Carbon monoxide -- Chemical properties ,Chemistry - Abstract
A combined photoelectron spectroscopy (PES) and density functional theory (DFT) investigation of the CO chemisorption behavior on the gold hexamer from one to three CO groups Au6(CO)(sub n)-(n=0-3) is reported. While the electron donor capability of CO is known to decrease the electron binding energies of Aum(CO)(sub n)-complexes, CO chemisorption on Au6(CO)(sub n)-(n=1-3) is observed to have very little effect on the electron binding energies of the first PES band of Au6(CO)(sub n)-(n=1-3).
- Published
- 2005
49. Artificial Aquaporin That Restores Wound Healing of Impaired Cells
- Author
-
Yan, Zhao-Jun, primary, Wang, Dongdong, additional, Ye, Zhongju, additional, Fan, Ting, additional, Wu, Gang, additional, Deng, Liyun, additional, Yang, Lu, additional, Li, Binxiao, additional, Liu, Jianwei, additional, Ma, Tonghui, additional, Dong, Chaoqing, additional, Li, Zhan-Ting, additional, Xiao, Lehui, additional, Wang, Yunfeng, additional, Wang, Wenning, additional, and Hou, Jun-Li, additional
- Published
- 2020
- Full Text
- View/download PDF
50. Hydrogen bonded oligohydrazide foldamers and their recognition for saccharides
- Author
-
Jun-Li Hou, Xue-Bin Shao, Guang-Ju Chen, Yan-Xia Zhou, Xi-Kui Jiang, and Zhan-Ting Li
- Subjects
Hydrazine -- Chemical properties ,Hydrogen bonding -- Research ,Chemistry - Abstract
The synthesis and characterization of the first series of hydrogen-bonding-driven-hydrazide foldamers has been described. These molecules represent novel examples of hydrogen-bonding-driven foldamers that act as artificial receptors for selective molecular recognition.
- Published
- 2004
Catalog
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