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Xiao Wang Dapeng Liu Shuyan Song Prof. Dr. Hongjie Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(16):5169-5173
New Pd(Pt) catalysts have been fabricated by assembling multicomponents of Fe3O4 and CeO2/Pd(Pt) on the surface of reduced graphene oxide (RGO) nanosheets in layers. The as‐obtained Pd(Pt) catalysts exhibit extremely high catalytic activity in the selective hydrogenation reaction of nitrobenzene. Owing to the presence of Fe3O4, the catalysts can be easily recycled from the catalytic system through magnetic separation. Their high activity, stability, and magnetic recyclability make the as‐obtained hybrids very promising as catalysts in catalytic applications. Compared to other traditional multishell magnetic catalysts that were prepared by means of layer‐by‐layer technology, our process is much more facile and more easily controlled. 相似文献
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Controlled Synthesis of Fe3O4/ZIF‐8 Nanoparticles for Magnetically Separable Nanocatalysts 下载免费PDF全文
Fei Pang Prof. Mingyuan He Prof. Jianping Ge 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6879-6887
Fe3O4/ZIF‐8 nanoparticles were synthesized through a room‐temperature reaction between 2‐methylimidazolate and zinc nitrate in the presence of Fe3O4 nanocrystals. The particle size, surface charge, and magnetic loading can be conveniently controlled by the dosage of Zn(NO3)2 and Fe3O4 nanocrystals. The as‐prepared particles show both good thermal stability (stable to 550 °C) and large surface area (1174 m2g?1). The nanoparticles also have a superparamagnetic response, so that they can strongly respond to an external field during magnetic separation and disperse back into the solution after withdrawal of the magnetic field. For the Knoevenagel reaction, which is catalyzed by alkaline active sites on external surface of catalyst, small Fe3O4/ZIF‐8 nanoparticles show a higher catalytic activity. At the same time, the nanocatalysts can be continuously used in multiple catalytic reactions through magnetic separation, activation, and redispersion with little loss of activity. 相似文献
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Alexander K. Tucker‐Schwartz Prof. Dr. Robin L. Garrell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(42):12718-12726
The organic oxidant TEMPO (2,2,4,4‐tetramethylpiperdine‐1‐oxyl) was immobilized on iron oxide (Fe3O4) superparamagnetic nanoparticles by employing strong metal‐oxide chelating phosphonates and azide/alkyne “click” chemistry. This simple preparation yields recyclable TEMPO‐coated nanoparticles with good TEMPO loadings. They have excellent magnetic response and efficiently catalyze the oxidation of a wide range of primary and secondary alcohols to aldehydes, ketones, and lactones under either aerobic acidic MnII/CuII oxidizing Minisci conditions, or basic NaOCl Anelli conditions. The nanoparticles could be recycled more than 20 times under the Minisci conditions and up to eight times under the Anelli conditions with good to excellent substrate conversions and product selectivities. Immobilization of the catalyst through a phosphonate linkage allows the particles to withstand acidic oxidizing environments with minimal catalyst leaching. Clicking TEMPO to the phosphonate prior to phosphonate immobilization, rather than after, ensures the clicked catalyst is the only species on the particle surface. This facilitates quantification of the catalyst loading. The stability of the phosphonate linker and simplicity of this catalyst immobilization method make this an attractive approach for tethering catalysts to oxide supports, creating magnetically separable catalysts that can be used under neutral or acidic conditions. 相似文献
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《中国化学》2017,35(9):1405-1410
Pd and Pdx Ni nanoparticles have been supported on reduced graphene oxide (Pd/rGO and Pdx Ni/rGO ) by using the microwave‐assisted heating method in glycol. The morphology, composition and electrochemical performance have been characterized by TEM , XRD , XPS and electrochemical methods. The XRD and XPS results show that there are no PdNi alloy particles formed in Pdx Ni/rGO and the composites exist mostly in the form of Pd0 and NiOOH species. The electrochemical results reveal that Pdx Ni/rGO synthesized from the feeding source of Pd and Ni with an atomic ratio of 4∶1 exhibits higher activity, better stability and smaller electron transfer resistance toward formic acid electro‐oxidation compared with commercial Pd/C, Pd/rGO and other Pdx Ni/rGO samples. The excellent electrocatalytic performance indicates that the addition of appropriate amount of Ni can greatly enhance the activity and stability of Pd catalysts for formic acid oxidation. 相似文献
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采用绿色、温和的方法合成了一种新型的磁性纳米复合材料(Fe3O4@PDA@RGO),并考察了其对水溶液中亚甲基蓝的吸附去除效果。多巴胺通过自聚合作用可以直接吸附到Fe3O4表面,其既是氧化石墨烯(GO)的还原剂,也是Fe3O4和还原态氧化石墨烯(RGO)组装的偶联剂。反应过程中无需热处理或加入其他有机试剂。利用透射电子显微镜(TEM)、红外光谱(FTIR)、X衍射光谱(XRD)和拉曼光谱等技术对制备的磁性纳米复合材料进行了表征。结果表明,Fe3O4@PDA@RGO具有较强的磁性(37.8 emu·g-1),对亚甲基蓝有较高的吸附去除能力(98 mg·g-1)。Fe3O4@PDA@RGO对亚甲基蓝的吸附能力随着p H值的增大而增强,其吸附过程符合拟二级反应动力学方程和Langmuir吸附模型。Fe3O4@PDA@RGO作为吸附剂,其性质稳定,经磁性分离可重复利用10次以上。 相似文献
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Efficient and Magnetically Recoverable “Click” PEGylated γ‐Fe2O3–Pd Nanoparticle Catalysts for Suzuki–Miyaura,Sonogashira, and Heck Reactions with Positive Dendritic Effects 下载免费PDF全文
Dr. Dong Wang Christophe Deraedt Dr. Lionel Salmon Christine Labrugère Laetitia Etienne Dr. Jaime Ruiz Prof. Didier Astruc 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(4):1508-1519
The engineering of novel catalytic nanomaterials that are highly active for crucial carbon–carbon bond formations, easily recoverable many times, and biocompatible is highly desirable in terms of sustainable and green chemistry. To this end, catalysts comprising dendritic “click” ligands that are immobilized on a magnetic nanoparticle (MNP) core, terminated by triethylene glycol (TEG) groups, and incorporate Pd nanoparticles (PdNPs) have been prepared. These nanomaterials are characterized by transmission electron microscopy (TEM), high‐resolution TEM, inductively coupled plasma analysis, Fourier transform infrared spectroscopy, X‐ray photoelectron spectra and energy‐dispersive X‐ray spectroscopy. They are shown to be highly active, dispersible, and magnetically recoverable many times in Suzuki, Sonogashira, and Heck reactions. In addition, a series of pharmacologically relevant or natural products were successfully synthesized using these magnetic PdNPs as catalyst. For comparison, related PdNP catalysts deposited on MNPs bearing linear “click” PEGylated ligands are also prepared. Strong positive dendritic effects concerning ligand loading, catalyst loading, catalytic activity, and recyclability are observed, that is, the dendritic catalysts are much more efficient than non‐dendritic analogues. 相似文献
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One‐Step Pyrolysis Preparation of 1.1.1 Oriented Gold Nanoplatelets Supported on Graphene and Six Orders of Magnitude Enhancement of the Resulting Catalytic Activity 下载免费PDF全文
Dr. Ana Primo Ivan Esteve‐Adell Dr. Simona N. Coman Natalia Candu Prof. Vasile I. Parvulescu Prof. Hermenegildo Garcia 《Angewandte Chemie (International ed. in English)》2016,55(2):607-612
Pyrolysis of chitosan films containing Au3+ renders 1.1.1 oriented Au nanoplatelets (20 nm lateral size, 3–4 nm height) on a few layers of N‐doped graphene ( /fl‐G), while the lateral sides were 0.0.1 oriented. Comparison of the catalytic activity of /fl‐G films with powders of unoriented Au NPs supported on graphene showed that /fl‐G films exhibit six orders of magnitude enhancement for three gold‐catalyzed reactions, namely, Ullmann‐like homocoupling, C? N cross coupling, and the oxidative coupling of benzene to benzoic acid. This enhancement is the result of the defined morphology, facet orientation of Au nanocrystals, and strong gold‐graphene interaction. 相似文献
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Growth of Fe3O4 Nanorod Arrays on Graphene Sheets for Application in Electromagnetic Absorption Fields 下载免费PDF全文
Huanming Zhang Prof. Dr. Chunling Zhu Prof. Dr. Yujin Chen Prof. Dr. Hong Gao 《Chemphyschem》2014,15(11):2261-2266
A facial strategy is developed to fabricate a three‐dimensional (3D) Fe3O4 nanorod array/graphene architecture, in which Fe3O4 nanorods with a length and diameter of about 600 and 100 nm, respectively, are grown on both surfaces of the graphene sheets. The measured electromagnetic parameters show that the 3D architecture exhibits excellent electromagnetic wave‐absorption properties, that is, more than 99 % of electromagnetic wave energy can be attenuated by the 3D architecture if it is added in only 20 wt % of the paraffin matrix, as the thickness of the absorber is in the range from 2.38 to 5.00 mm. The analysis of the electromagnetic (EM) absorption mechanism reveals that the excellent EM absorption properties are related to the special 3D architecture, and therefore, the construction of graphene‐based 3D heteronanostructures is effective in obtaining lightweight EM absorbers with strong absorption properties. 相似文献
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CuxCo1−xO Nanoparticles on Graphene Oxide as A Synergistic Catalyst for High‐Efficiency Hydrolysis of Ammonia–Borane 下载免费PDF全文
Kun Feng Dr. Jun Zhong Binhua Zhao Hui Zhang Dr. Lai Xu Prof. Dr. Xuhui Sun Prof. Dr. Shuit‐Tong Lee 《Angewandte Chemie (International ed. in English)》2016,55(39):11950-11954
Ammonia–borane (AB) is an excellent material for chemical storage of hydrogen. However, the practical utilization of AB for production of hydrogen is hindered by the need of expensive noble metal‐based catalysts. Here, we report CuxCo1?xO nanoparticles (NPs) facilely deposited on graphene oxide (GO) as a low‐cost and high‐performance catalyst for the hydrolysis of AB. This hybrid catalyst exhibits an initial total turnover frequency (TOF) value of 70.0 (H2) mol/(Cat‐metal) mol?min, which is the highest TOF ever reported for noble metal‐free catalysts, and a good stability keeping 94 % activity after 5 cycles. Synchrotron radiation‐based X‐ray absorption spectroscopy (XAS) investigations suggested that the high catalytic performance could be attributed to the interfacial interaction between CuxCo1?xO NPs and GO. Moreover, the catalytic hydrolysis mechanism was studied by in situ XAS experiments for the first time, which reveal a significant water adsorption on the catalyst and clearly confirm the interaction between AB and the catalyst during hydrolysis. 相似文献
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Graphene‐based composites offer enhanced catalytic performance of metal and semiconductor nanoparticles, but their development is challenging because catalytic performance strongly depends on the structure and composition of the composite. Herein we show that the catalytic performance of a nanoparticle–graphene composite is very dependent on catalyst loading, which can be optimized for simultaneous enhancement of activity and selectivity. A glassy carbon working electrode has been modified with a gold nanoparticle–graphene (Au–G) composite with a varied number of gold nanoparticles per graphene, so that the conducting property of graphene and the electrocatalytic property of the metal were effectively coupled to give the best catalytic activity and selectivity. The modified electrode was used for simultaneous electrochemical detection of a mixture of electroactive species with high sensitivity. This result shows that the catalytic performance of a graphene‐based composite is sensitive to the catalyst loading and should be optimized for the best performance. 相似文献
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Shaojun Guo Shaojun Dong Prof. Erkang Wang Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(10):2416-2424
Multifunctional nanostructures : By using 3‐aminopropyltrimethoxysilane as a linker, Au nanoparticles (NPs), Au shells, flowerlike Au/Pt hybrid NPs, and Ag or Au/Ag core/shell NPs could be supported on the surface of superparamagnetic Fe3O4 spheres to construct hybrid nanostructures that display near‐IR absorption, high catalytic activity towards an electron‐transfer reaction, or excellent surface‐enhanced Raman scattering activity. The picture shows SEM images of Fe3O4 spheres coated with Au shells (top) and with Au/Pt hybrid NPs (bottom).
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Poly(3‐hexylthiophene) (P3HT) supramolecular structures are fabricated on P3HT‐dispersed reduced graphene oxide (RGO) monolayers and surfactant‐free RGO monolayers. P3HT is able to disperse RGO in hot anisole/N,N‐dimethylformamide solvents, and forms nanowires on RGO surfaces through a RGO induced crystallization process. The TEM and AFM investigation of the resultant P3HT/RGO composites shows that P3HT nanowires grow from RGO, and connect individual RGO monolayers. Raman spectroscopy confirms the interaction between P3HT and RGO, which allows the manipulation of the RGO electrical properties. Such a bottom‐up approach provides interesting graphene‐based composites for nanometer‐scale electronics.
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Facile Synthesis of Platinum–Cerium(IV) Oxide Hybrids Arched on Reduced Graphene Oxide Catalyst in Reverse Micelles with High Activity and Durability for Hydrolysis of Ammonia Borane 下载免费PDF全文
Qilu Yao Yao Shi Prof. Xiaoliang Zhang Prof. Xiangshu Chen Prof. Zhang‐Hui Lu 《化学:亚洲杂志》2016,11(22):3251-3257
Highly dispersed Pt‐CeO2 hybrids arched on reduced graphene oxide (Pt‐CeO2/rGO) were facilely synthesized by a combination of the reverse micelle technique and a redox reaction without any additional reductant or surfactant. Under a N2 atmosphere, the redox reaction between Ce3+ and Pt2+ occurs automatically in alkaline solution, which results in the formation of Pt‐CeO2/rGO nanocomposites (NCs). The as‐synthesized Pt‐CeO2/rGO NCs exhibit superior catalytic performance relative to that shown by the free Pt nanoparticles, Pt/rGO, Pt‐CeO2 hybrid, and the physical mixture of Pt‐CeO2 and rGO; furthermore, the nanocomposites show significantly better activity than the commercial Pt/C catalyst toward the hydrolysis of ammonia borane (NH3BH3) at room temperature. Moreover, the Pt‐CeO2/rGO NCs have remarkable stability, and 92 % of their initial catalytic activity is preserved even after 10 runs. The excellent activity of the Pt‐CeO2/rGO NCs can be attributed not only to the synergistic structure but also to the electronic effects of the Pt‐CeO2/rGO NCs among Pt, CeO2, and rGO. 相似文献
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Tran Thanh Tung Jean‐Francois Feller TaeYoung Kim Hyeongkeun Kim Woo Seok Yang Kwang S. Suh 《Journal of polymer science. Part A, Polymer chemistry》2012,50(5):927-935
Hybrid materials of Fe3O4‐decorated reduced graphene oxide (Fe3O4‐RGO) and poly(3,4‐ethylenedioxythiophene) (PEDOT) were prepared by poly(ionic liquid)‐mediated hybridization. In this hybrid material, poly(ionic liquid) was found to perform multiple roles for: (1) stabilizing Fe3O4‐RGO against aggregation in the reaction medium, (2) transferring Fe3O4‐RGO nanomaterials from aqueous into organic phase, and (3) associating Fe3O4‐RGO nanomaterials with PEDOT. The hybrid materials of Fe3O4‐RGO with PEDOT showed the lowest surface resistivity of 80 Ω sq?1 at an RGO‐Fe3O4 loading of 1 wt %, and exhibited superparamagnetic behavior with an electromagnetic interference shielding effectiveness of 22 dB. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
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Core–Shell LiFePO4/Carbon‐Coated Reduced Graphene Oxide Hybrids for High‐Power Lithium‐Ion Battery Cathodes 下载免费PDF全文
Sung Hoon Ha Prof. Yun Jung Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):2132-2138
Core‐shell carbon‐coated LiFePO4 nanoparticles were hybridized with reduced graphene (rGO) for high‐power lithium‐ion battery cathodes. Spontaneous aggregation of hydrophobic graphene in aqueous solutions during the formation of composite materials was precluded by employing hydrophilic graphene oxide (GO) as starting templates. The fabrication of true nanoscale carbon‐coated LiFePO4‐rGO (LFP/C‐rGO) hybrids were ascribed to three factors: 1) In‐situ polymerization of polypyrrole for constrained nanoparticle synthesis of LiFePO4, 2) enhanced dispersion of conducting 2D networks endowed by colloidal stability of GO, and 3) intimate contact between active materials and rGO. The importance of conducting template dispersion was demonstrated by contrasting LFP/C‐rGO hybrids with LFP/C‐rGO composites in which agglomerated rGO solution was used as the starting templates. The fabricated hybrid cathodes showed superior rate capability and cyclability with rates from 0.1 to 60 C. This study demonstrated the synergistic combination of nanosizing with efficient conducting templates to afford facile Li+ ion and electron transport for high power applications. 相似文献
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Daniel Canseco‐Gonzalez Dr. Andrzej Gniewek Michal Szulmanowicz Dr. Helge Müller‐Bunz Prof. Dr. Anna M. Trzeciak Prof. Dr. Martin Albrecht 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(19):6055-6062
A series of PEPPSI‐type palladium(II) complexes was synthesized that contain 3‐chloropyridine as an easily removable ligand and a triazolylidene as a strongly donating mesoionic spectator ligand. Catalytic tests in Suzuki–Miyaura cross‐coupling reactions revealed the activity of these complexes towards aryl bromides and aryl chlorides at moderate temperatures (50 °C). However, the impact of steric shielding was the inverse of that observed with related normal Nheterocyclic carbenes (imidazol‐2‐ylidenes) and sterically congested mesityl substituents induced lower activity than small alkyl groups. Mechanistic investigations, including mercury poisoning experiments, TEM analyses, and ESI mass spectrometry, provide evidence for ligand dissociation and the formation of nanoparticles as a catalyst resting state. These heterogeneous particles provide a reservoir for soluble palladium atoms or clusters as operationally homogeneous catalysts for the arylation of aryl halides. Clearly, the substitution of a normal N‐heterocyclic carbene for a more basic triazolylidene ligand in the precatalyst has a profound impact on the mode of action of the catalytic system. 相似文献