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copper catalyst

Dogukan H Apaydin, Hathaichanok Seelajaroen, Orathip Pengsakul, Patchanita Thamyongkit, Niyazi Serdar Sariciftci, Julia Kunze-Liebhäuser, Engelbert Portenkirchner
We report on a self-assembled system comprising a molecular copper-porphyrin photoelectrocatalyst, 5-(4-carboxy-phenyl)-10,15,20-triphenylporphyrinatocopper(II) (CuTPP-COOH), covalently bound to self-organized, anodic titania nanotube arrays (TiO2 NTs) for photoelectrochemical reduction of oxygen. Visible light irradiation of the porphyrin-covered TiO2 NTs under cathodic polarization up to -0.3 V vs. Normal hydrogen electrode (NHE) photocatalytically produces H2 O2 in pH neutral electrolyte, at room temperature and without need of sacrificial electron donors...
April 24, 2018: ChemCatChem
Cao-Thang Dinh, Thomas Burdyny, Md Golam Kibria, Ali Seifitokaldani, Christine M Gabardo, F Pelayo García de Arquer, Amirreza Kiani, Jonathan P Edwards, Phil De Luna, Oleksandr S Bushuyev, Chengqin Zou, Rafael Quintero-Bermudez, Yuanjie Pang, David Sinton, Edward H Sargent
Carbon dioxide (CO2 ) electroreduction could provide a useful source of ethylene, but low conversion efficiency, low production rates, and low catalyst stability limit current systems. Here we report that a copper electrocatalyst at an abrupt reaction interface in an alkaline electrolyte reduces CO2 to ethylene with 70% faradaic efficiency at a potential of -0.55 volts versus a reversible hydrogen electrode (RHE). Hydroxide ions on or near the copper surface lower the CO2 reduction and carbon monoxide (CO)-CO coupling activation energy barriers; as a result, onset of ethylene evolution at -0...
May 18, 2018: Science
Sujeong Heo, Sunghoon Hong, Bo Kyeong Jeon, Chengbin Li, Ji Man Kim, Young Min Jo, Wooram Kim, Jong-Ki Jeon
Ordered mesoporous Cu-Mn binary metal oxide (meso-CuMnOx) catalysts were successfully synthesized by a hard-templating method from a mesoporous silica template with a cubic Ia3d mesostructure (KIT-6) or hydrophobic KIT-6, exhibiting a well-developed crystalline framework, a regular pore size distribution and a high surface area. The copper and manganese elements in the mesoporous Cu-Mn binary metal oxides (meso-CuMnOx-N and meso-CuMnOx-HP), obtained from the KIT-6 and hydrophobic KIT-6, respectively, were homogeneously dispersed in the whole particles...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Thenmozhi Sukumar, Dharmaraj Nallasamy
Poly(vinyl pyrrolidone) (PVP)/copper oxide composite nanofibers were prepared by electrospinning technique using PVP and copper acetate as precursors and calcinated at high temperature to yield polymer free, phase pure copper oxide nanofibers (CuO NFs). The powder X-ray diffraction (XRD) pattern, transmission electron microscopic (TEM) images and selected area electron diffraction pattern (SAED) results showed that the calcinated CuO NFs were crystalline with 166 nm diameter and monoclinic in phase. From the catalytic application point of view, the newly prepared electrospun CuO NFs were tested for N-arylation of imidazole using aryl halides...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Tanasan Intana, Karin Föttinger, Günther Rupprechter, Paisan Kongkachuichay
Copper species in the structure of Cu/core-shell Al-MCM-41 catalysts prepared by different techniques of Cu loading-substitution (S), ion-exchange (E), and impregnation (I) methods-were tested for NO reduction via a selective catalytic reaction with methane. Cerium was added to enhance the performance of copper. It was found that the 1.5%Ce-SEI-Cu/Al-MCM-41, in which Cu was loaded by all three techniques gave the highest NO conversion of 85% at 500 °C. Based on the results from FT-IR in-situ experiment, the mechanism of SCR-CH4 reaction is proposed...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Imran Ali, Omar M L Alharbi, Zeid A Alothman, Ahmad Yacine Badjah
Titanium oxide nanoparticles were doped with copper and characterized by XRD, FT-IR, TEM and SEM. The surface morphology was spherical with 15-26 nm as particle size. The doped titanium oxide (Co/TiO2 ) nanomaterial was used for photodegradation of amido black dye in water. The maximum photodegradation of amido black obtained was 90%. The values of free energy, and enthalpy were negative, indicating spontaneous photodegradation of amido black dye. The photodegradation of amido black dye obeyed first order kinetic model...
May 16, 2018: Photochemistry and Photobiology
Xin Xie, Jingjun Liu, Tuanfeng Li, Ye Song, Feng Wang
Note that 3d transition metal and nitrogen co-doped carbon materials (TM-N-C) are considered as the most promising next-generation electrocatalysts alternative to precious Pt for oxygen reduction reaction (ORR). Herein, we have fabricated a Cu-N-C catalyst through directly grafting copper-nitrogen complexes composed by cuprous chloride and ammonia water onto the surface of an industrial carbon black at 500℃. In an alkaline environment, the synthesized catalyst exhibits excellent ORR catalytic activity, which is comparable to the state-of-the-art Pt/C catalyst but far exceeding that obtained by the original carbon...
May 16, 2018: Chemistry: a European Journal
Caihong Zheng, Fangling Lu, Hanwei Lu, Jie Xin, Yi Deng, Dali Yang, Shengchun Wang, Zhiliang Huang, Meng Gao, Aiwen Lei
A new protocol for C-S bond formation was developed by selective cross-coupling between a thiyl radical and an isobutyronitrile radical. Using this strategy, a series of valuable α-alkylthionitrile derivatives were synthesized from basic starting materials. Preliminary mechanistic investigation was performed by EPR and XAFS, revealing that the transient thiyl radical could be stabilized by a copper catalyst to a persistent one. Therefore, on the basis of the persistent radical effect, selective radical-radical cross-coupling between the thiyl radical and the isobutyronitrile radical was achieved successfully in this work...
May 16, 2018: Chemical Communications: Chem Comm
Donglin He, Huiping Zhang, Ying Yan
Cu-ZSM-5 catalysts were prepared by chemical vapour deposition for catalytic wet peroxide oxidation (CWPO) of phenol in a fixed bed reactor. Firstly, Cu-ZSM-5 catalysts with Cu loading of 0.5, 2, and 6 wt% were prepared and characterized by X-ray diffraction (XRD), N2 adsorption-desorption and X-ray photoelectron spectra (XPS). The characterization results demonstrated that CuO was uniformly dispersed on ZSM-5 with slight effect on the structure properties of the support. Then, several variables, such as the copper loading, reaction temperature, catalyst bed height and feed flow rate were investigated in the CWPO of phenol in aqueous solution at high concentration (1000 ppm)...
April 2018: Royal Society Open Science
Laurel M Heckman, Zhi He, Timothy F Jamison
Highly functionalized 2-arylindoles were synthesized from 2-alkenylarylisocyanides and arylboronic acids using a simple, inexpensive copper catalyst. The reaction exhibits excellent functional group tolerance for both the arylisocyanide and boronic acid coupling partners. To avoid the direct handling of the pungent arylisocyanide starting materials, continuous flow chemistry is further demonstrated to provide safe and effective access to 2-arylindoles through in situ dehydration and cyclization of easy-to-handle 2-alkenyl- N-formylanilines...
May 15, 2018: Organic Letters
Wu Wen, Biao Han, Feng Yan, Liang Ding, Bojie Li, Liansheng Wang, Lei Zhu
We describe here the preparation of copper nanoparticles stabilized on a chitosan/poly (vinyl alcohol) composite film. This material could catalyze the borylation of α,β-unsaturated acceptors in aqueous media under mild conditions. The corresponding organoboron compounds as well as their converted β-hydroxyl products were all obtained in good to excellent yields. It is noteworthy that this catalyst of copper nanoparticles can be easily recycled eight times and remained catalytically reactive. This newly developed methodology provides an efficient and sustainable pathway for the synthesis of organoboron compounds and application of copper nanoparticles...
May 14, 2018: Nanomaterials
Navnath D Rode, Issam Abdalghani, Antonio Arcadi, Massimiliano Aschi, Marco Chiarini, Fabio Marinelli
β-2-aminophenyl)-α,β-ynones afforded 3-unsubstituted 2-acylindoles in good yields in the presence of 20 mol% of AgOTf under MW heating. The use CuOTf as catalyst resulted in a similar reaction outcome, generally with a lower efficiency. This transformation represents the first example of 5-endo-dig cyclization of 2-alkynylanilines bearing an acyl group linked to the triple bond. By contrast with the previously reported gold-catalyzed reaction of β-2-aminophenyl)-α,β-ynones, that resulted in the formation of dibenzo[1,5]diazocines through a sequential process triggered by an intermolecular hydroamination, a selective intramolecular anti-Michael hydroamination was observed in the present study by mean of silver/copper catalysis...
May 14, 2018: Journal of Organic Chemistry
Xiaonan Shi, Xi Chen, Muhua Wang, Xinying Zhang, Xuesen Fan
A highly regioselective and versatile synthesis of acylated N-heterocycles from the cascade reactions of saturated cyclic amines with 2-oxo-2-arylacetic acids is presented. Mechanistically, the formation of the title compounds involves firstly a C(sp3)-H bond dehydrogenation of cyclic amine to give an enamine intermediate followed by its cross coupling with the acyl species in situ generated through the decarboxylation of 2-oxo-2-arylacetic acid. Interestingly, in this cascade process the copper catalyst is believed to play a crucial role not only in dehydrogenation, but also in decarboxylation and cross coupling reaction...
May 14, 2018: Journal of Organic Chemistry
Joana R Góis, Fábio Reis, Ana M Almeida, Patrícia Pereira, Fani Sousa, Arménio C Serra, Jorge F J Coelho
Well-defined oligo(ethylene glycol) methyl ether methacrylate (OEOMA) based block copolymers with cationic segments composed by N,N-(dimethylamino) ethyl methacrylate (DMAEMA) and/or 2-(diisopropylamino) ethyl methacrylate (DPA) were developed under biorelevant reaction conditions. These brush-type copolymers were synthesized through supplemental activator and reducing agent (SARA) atom transfer radical polymerization (ATRP) using sodium dithionite as SARA agent. The synthesis was carried out using an eco-friendly solvent mixture, very low copper catalyst concentration, and mild reaction conditions...
May 3, 2018: Colloids and Surfaces. B, Biointerfaces
Yi Wang, Marco Fantin, Krzysztof Matyjaszewski
A dual-concurrent atom transfer radical polymerization/reversible addition-fragmentation chain-transfer (ATRP/RAFT) system is used to control a radical polymerization by electrochemical reduction of small amount of copper complexes in the presence of a chain transfer agent (CTA). Electrochemical ATRP conditions provide a continuous supply of radicals, while the CTA aids the control over molecular weight and dispersity of poly(n-butyl acrylate), even in the presence of low ppm amounts of catalyst. The polymerization could be turned "on" and "off" by shifting electrolysis potential...
May 11, 2018: Macromolecular Rapid Communications
Qingfu Ban, Junjie Du, Wen Sun, Jianxin Chen, Si Wu, Jie Kong
Intramolecular Cu-containing amphiphilic hyperbranched polytriazoles are purposefully designed and synthesized via a Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, and are self-assembled into spherical assemblies. Based on the metal coordination ability of triazole groups, the copper catalyst can be intramolecularly coordinated with triazole groups in the CuAAC, producing the copper-triazole coordination polyprodrugs. Unexpectedly, the amphiphilic hyperbranched polytriaozle assemblies can also be applied as fluorescent nanoprobes with aggregation-induced emission enhancement...
May 11, 2018: Macromolecular Rapid Communications
Beatriz Gamarra, Rachel Howcroft, Ashley McCall, János Dani, Zsigmond Hajdú, Emese Gyöngyvér Nagy, László D Szabó, László Domboróczki, Ildikó Pap, Pál Raczky, Antónia Marcsik, Zsuzsanna K Zoffmann, Tamás Hajdu, Robin N M Feeney, Ron Pinhasi
The development of farming was a catalyst for the evolution of the human diet from the varied subsistence practices of hunter-gatherers to the more globalised food economy we depend upon today. Although there has been considerable research into the dietary changes associated with the initial spread of farming, less attention has been given to how dietary choices continued to develop during subsequent millennia. A paleogenomic time transect for 5 millennia of human occupation in the Great Hungarian Plain spanning from the advent of the Neolithic to the Iron Age, showed major genomic turnovers...
2018: PloS One
Allison M Bergmann, Adam M Oldham, Wei You, M Kevin Brown
A method for the Cu-catalyzed cross-coupling of both aryl and alkylboranes with aryl bromides is described. The method employs an inexpensive Cu-catalyst and functions for a variety of heterocyclic as well as electron deficient aryl bromides. In addition, aryl iodides of varying substitution patterns and electronic properties work well.
May 10, 2018: Chemical Communications: Chem Comm
Baran Eren, Daniel Torres, Osman Karslıoğlu, Zongyuan Liu, Cheng Hao Wu, Dario Stacchiola, Hendrik Bluhm, Gabor A Somorjai, Miquel Salmeron
We studied the structure of the copper-cobalt (CuCo) surface alloy, formed by Co deposition on Cu(110), in dynamic equilibrium with CO. Using scanning tunneling microscopy (STM), we found that in vacuum at room temperature and at low Co coverage, clusters of a few Co atoms substituting Cu atoms form at the surface. At CO pressures in the Torr range, we found that up to 2.5 CO molecules can bind on a single Co atom, in carbonyl-like configurations. Based on high-resolution STM images, together with density function theory calculations, we determined the most stable CuCo cluster structures formed with bound CO...
May 8, 2018: Journal of the American Chemical Society
Donghao Wang, Wenyi Ding, Kaiyue Zhou, Shutong Guo, Qiang Zhang, David M Haddleton
Immobilization of enzyme could offer the biocatalyst with increased stability and important recoverability, which plays a vital role for the enzyme's industrial applications. In this study, we present a new strategy to build an intelligent enzyme carrier by coating titania nanoparticles with thermoresponsive epoxy-functionalized polymers. Zero-valent copper mediated living radical polymerization (Cu(0)-LRP) was utilized herein to copolymerize N-isopropylacrylamide (NIPAM) and glycidyl acrylate (GA), directly from an unprotected dopamine-functionalized initiator, in order to obtain an epoxy-containing polymer with terminal anchor for the "grafting to" or "one-pot" modification of titania nanoparticles...
May 8, 2018: Biomacromolecules
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