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https://www.readbyqxmd.com/read/29327475/tuning-the-activity-of-carbon-for-electrocatalytic-hydrogen-evolution-via-an-iridium-cobalt-alloy-core-encapsulated-in-nitrogen-doped-carbon-cages
#1
Peng Jiang, Jitang Chen, Changlai Wang, Kang Yang, Shipeng Gong, Shuai Liu, Zhiyu Lin, Mengsi Li, Guoliang Xia, Yang Yang, Jianwei Su, Qianwang Chen
Graphene, a 2D material consisting of a single layer of sp2 -hybridized carbon, exhibits inert activity as an electrocatalyst, while the incorporation of heteroatoms (such as N) into the framework can tune its electronic properties. Because of the different electronegativity between N and C atoms, electrons will transfer from C to N in N-doped graphene nanosheets, changing inert C atoms adjacent to the N-dopants into active sites. Notwithstanding the achieved progress, its intrinsic activity in acidic media is still far from Pt/C...
January 12, 2018: Advanced Materials
https://www.readbyqxmd.com/read/29323453/patterning-graphene-surfaces-with-iron-oxide-embedded-mesoporous-polypyrrole-and-derived-n-doped-carbon-of-tunable-pore-size
#2
Shuyan Zhu, Hao Tian, Nan Wang, Bin Chen, Yiyong Mai, Xinliang Feng
This study develops a novel strategy, based on block copolymer self-assembly in solution, for preparing two-dimensional (2D) graphene-based mesoporous nanohybrids with well-defined large pores of tunable sizes, by employing polystyrene-block-poly(ethylene oxide) (PS-b-PEO) spherical micelles as the pore-creating template. The resultant 2D nanohybrids possess a sandwich-like structure with Fe2 O3 nanoparticle-embedded mesoporous polypyrrole (PPy) monolayers grown on both sides of reduced graphene oxide (rGO) nanosheets (denoted as mPPy-Fe2 O3 @rGO)...
January 11, 2018: Small
https://www.readbyqxmd.com/read/29319703/tailoring-2d-and-3d-molecular-sieves-structures-for-polyolefin-composites-do-all-roads-lead-to-remarkable-performances
#3
H M Moura, N L Gibbons, S A Miller, H O Pastore
Multiple synthetic strategies were performed in order to tether a zirconium-based catalyst to the 2D and 3D molecular sieves for olefin polymerizations. The anchoring of fluorene silane to the mesoporous MCM-41 was performed in order to obtain a stable catalyst for olefin polymerization (1@MCM-41). Using spectroscopic methods, this system was shown to have the metal center locked on a face down conformation with the surface. Also, immobilized zirconium complexes have been prepared on three different types of aminopropyl-modified supports (2@magadiite, 2@MCM-41 and 3@MCM-48)...
January 10, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29301213/lithium-complexes-derived-of-benzylphosphines-synthesis-characterization-and-evaluation-in-the-rop-of-rac-lactide-and-%C3%AE%C2%B5-caprolactone
#4
Ernesto Rufino-Felipe, Miguel-Ángel Muñoz-Hernández, Virginia Montiel-Palma
A series of lithium complexes ([Ph₂P(o-C₆H₄-CH₂Li·TMEDA)] (1-Li), [PhP(o-C₆H₄-CH₃)(o-C₆H₄-CH₂Li·TMEDA)] (2-Li), [PhP(o-C₆H₄-CH₂Li·TMEDA)₂] (2-Li₂) and [P(o-C₆H₄-CH₂Li·TMEDA)₃] (3-Li₃)) was prepared from mono-, di- and tri-benzylphosphines and varying amounts of nBuLi and was characterized extensively by IR and ¹H, ⁷Li, 13C and 31P NMR spectroscopy. The molecular structures of complexes 1-Li and 2-Li were determined by single-crystal X-ray diffraction studies. The two complexes have monomeric structures in the solid state comprising seesaw lithium atoms...
December 30, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29298388/defect-free-encapsulation-of-fe0-in-2d-fused-organic-networks-as-a-durable-oxygen-reduction-electrocatalyst
#5
Seok-Jin Kim, Javeed Mahmood, Changmin Kim, Gao-Feng Han, Seong-Wook Kim, Sun-Min Jung, Guomin Zhu, James J De Yoreo, Guntae Kim, Jong-Beom Baek
Because they provide lower-cost but comparable activity to precious platinum (Pt)-based catalysts, non-precious iron (Fe)-based materials, such as Fe/Fe3C and Fe-N-C, have gained considerable attention as electrocatalysts for the oxygen reduction reaction (ORR). However, their practical application is hindered by their poor stability, which is attributed to the defective protection of extremely unstable Fe nanoparticles. Here, we introduce a synthesis strategy for a stable Fe-based electrocatalyst, which was realized by defect-free encapsulation of Fe nanoparticles using a two-dimensional (2D) phenazine-based fused aromatic porous organic network (Aza-PON)...
January 3, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29274558/one-step-prepared-cobalt-based-nanosheet-as-an-efficient-heterogeneous-catalyst-for-activating-peroxymonosulfate-to-degrade-caffeine-in-water
#6
Kun-Yi Andrew Lin, Hong-Kai Lai, Shaoping Tong
Two-dimensional (2D) planar cobalt-containing materials are promising catalysts for activating peroxymonosulfate (PMS) to degrade contaminants because 2D sheet-like morphology provides large reactive surfaces. However, preparation of these sheet-supported cobaltic materials typically involves multiple steps and complex reagents, making them less practical for PMS activation. In this study, a cobalt-based nanosheet (CoNS) is particularly developed using a one-step hydrothermal process with a single reagent in water...
December 16, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29244721/constructing-sheet-on-sheet-structured-graphitic-carbon-nitride-reduced-graphene-oxide-layered-mno%C3%A2-ternary-nanocomposite-with-outstanding-catalytic-properties-on-thermal-decomposition-of-ammonium-perchlorate
#7
Jianhua Xu, Dongnan Li, Yu Chen, Linghua Tan, Bo Kou, Fushun Wan, Wei Jiang, Fengsheng Li
We unprecedentedly report that layered MnO₂ nanosheets were in situ formed onto the surface of covalently bonded graphitic carbon nitride/reduced graphene oxide nanocomposite (g-C₃N₄/rGO), forming sheet-on-sheet structured two dimension (2D) graphitic carbon nitride/reduced graphene oxide/layered MnO₂ ternary nanocomposite (g-C₃N₄/rGO/MnO₂) with outstanding catalytic properties on thermal decomposition of ammonium perchlorate (AP). The covalently bonded g-C₃N₄/rGO was firstly prepared by the calcination of graphene oxide-guanidine hydrochloride precursor (GO-GndCl), following by its dispersion into the KMnO₄ aqueous solution to construct the g-C₃N₄/rGO/MnO₂ ternary nanocomposite...
December 15, 2017: Nanomaterials
https://www.readbyqxmd.com/read/29240716/impedance-spectroscopy-analysis-and-equivalent-circuit-modeling-of-graphene-oxide-solutions
#8
Youngbin Yoon, Jeonghoo Jo, Seungdu Kim, In Gyu Lee, Byung Jin Cho, Myunghun Shin, Wan Sik Hwang
The optical and electrical characteristics of a graphene oxide solution (GS) with different graphene oxide (GO) concentrations in de-ionized water are investigated via the electrochemical impedance spectroscopy (EIS) method. The measurement results produced by the EIS for the GS are represented with both Bode and Nyquist plots in a frequency range from 1 kHz to 10 MHz. Using these results, we develop an equivalent circuit model as a function of the GO concentration, representing the GS as a mixed circuit of two-dimensional (2D) GO dispersed in parallel in de-ionized (DI) water...
December 14, 2017: Nanomaterials
https://www.readbyqxmd.com/read/29239096/well-defined-cobalt-catalyst-with-n-doped-carbon-layers-enwrapping-the-correlation-between-surface-atomic-structure-and-electrocatalytic-property
#9
Youkui Zhang, Yunxiang Lin, Hongliang Jiang, Chuanqiang Wu, Hengjie Liu, Changda Wang, Shuangming Chen, Tao Duan, Li Song
Admittedly, the surface atomic structure of heterogenous catalysts toward the electrochemical oxygen reduction reaction (ORR) are accepted as the important features that can tune catalytic activity and even catalytic pathway. Herein, a surface engineering strategy to controllably synthesize a carbon-layer-wrapped cobalt-catalyst from 2D cobalt-based metal-organic frameworks is elaborately demonstrated. Combined with synchrotron radiation X-ray photoelectron spectroscopy, the soft X-ray absorption near-edge structure results confirmed that rich covalent interfacial CoNC bonds are efficiently formed between cobalt nanoparticles and wrapped carbon-layers during the polydopamine-assisted pyrolysis process...
December 14, 2017: Small
https://www.readbyqxmd.com/read/29216600/ethylene-formation-by-dehydration-of-ethanol-over-medium-pore-zeolites
#10
Kinga Gołąbek, Karolina A Tarach, Urszula Filek, Kinga Góra-Marek
In this work, the role of pore arrangement of 10-ring zeolites ZSM-5, TNU-9 and IM-5 on their catalytic properties in ethanol transformation were investigated. Among all the studied catalysts, the zeolite IM-5, characterized by limited 3-dimensionality, presented the highest conversion of ethanol and the highest yields of diethyl ether (DEE) and ethylene. The least active and selective to ethylene and C3+ products was zeolite TNU-9 with the largest cavities formed on the intersection of 10-ring channels. The catalysts varied, however, in lifetime, and their deactivation followed the order: IM-5>TNU-9>ZSM-5...
November 23, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29215106/in-situ-synthesis-of-novel-cu2co3-oh-2-decorated-2d-tio2-nanosheets-with-efficient-photocatalytic-h2-evolution-activity
#11
Hao Xu, Dongsheng Dai, Songsong Li, Lei Ge, Yangqin Gao
Semiconductor-based photocatalytic hydrogen evolution from water with earth-abundant and low cost co-catalysts has attracted much attention. Herein, novel Cu2(OH)2CO3 decorated 2D TiO2 nanosheets for photocatalytic water splitting were synthesized by a facile in situ synthetic method. The chemical and photophysical properties of Cu2(OH)2CO3/TiO2 nanosheets were investigated by X-ray diffractometry (XRD), transmission electron microscopy (TEM), UV-vis diffusion reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) analysis...
December 7, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29194811/organic-inorganic-hybrid-materials-multi-functional-solids-for-multi-step-reaction-processes
#12
Avelino Corma, Urbano Díaz
The design of new hybrid materials with tailored properties at the nano-, meso- and macro-scale, with the use of structural functional nanobuilding units, is carried out to obtain specific multi-functional materials. Organization into controlled 1D, 2D and 3D architectures with selected functionalities is key for developing advanced catalysts, but this is hardly accomplished using conventional techniques. The use of pre-formed nanostructures, derived either from known materials or made with specific innovative synthetic methodologies, has enormous potential in the generation of multi-site catalytic materials for one-pot processes...
November 30, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29181970/catalyst-controlled-structural-divergence-selective-intramolecular-7-endo-dig-and-6-exo-dig-post-ugi-cyclization-for-the-synthesis-of-benzoxazepinones-and-benzoxazinones
#13
Karandeep Singh, Bhanwar Kumar Malviya, Tapta Kanchan Roy, Venus Singh Mithu, Vimal K Bhardwaj, Ved Prakash Verma, Swapandeep Singh Chimni, Siddharth Sharma
Metal catalyzed post-Ugi cyclization of bis-amides is reported in this study. Exposure of bis-amides to Pd(II) catalyst triggered the formation of seven-membered benzoxazepinones. This investigation established that changing the catalyst to a Echavarren's gold(I) turned off cyclization to seven member ring and turned on 6-exo-dig annulations to afford family of six-membered benzoxazinones. To support the proposed mechanisms, quantum chemical based density functional theory calculations has been performed and validated...
November 28, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29178337/roll-to-roll-production-of-layer-controlled-molybdenum-disulfide-a-platform-for-2d-semiconductor-based-industrial-applications
#14
Yi Rang Lim, Jin Kyu Han, Seong Ku Kim, Young Bum Lee, Yeoheung Yoon, Seong Jun Kim, Bok Ki Min, Yooseok Kim, Cheolho Jeon, Sejeong Won, Jae-Hyun Kim, Wooseok Song, Sung Myung, Sun Sook Lee, Ki-Seok An, Jongsun Lim
A facile methodology for the large-scale production of layer-controlled MoS2 layers on an inexpensive substrate involving a simple coating of single source precursor with subsequent roll-to-roll-based thermal decomposition is developed. The resulting 50 cm long MoS2 layers synthesized on Ni foils possess excellent long-range uniformity and optimum stoichiometry. Moreover, this methodology is promising because it enables simple control of the number of MoS2 layers by simply adjusting the concentration of (NH4 )2 MoS4 ...
November 27, 2017: Advanced Materials
https://www.readbyqxmd.com/read/29178167/interfacial-interaction-in-monolayer-and-few-layer-sns-ch3nh3pbi3-perovskite-van-der-waals-heterostructures-and-its-effects-on-electronic-and-optical-properties
#15
Jian-Cai Li, Zeng-Xi Wei, Wei-Qing Huang, Li-Li Ma, Wangyu Hu, Ping Peng, Gui-Fang Huang
High light absorption coefficient and long-range hot-carrier transport of hybrid organic-inorganic perovskite enable its composites huge potential in solar energy conversion and environmental protection. Understanding interfacial interaction and its effect are paramount for designing perovskite-based heterostructures with desirable properties. Here we systematically investigate the interfacial interaction in monolayer and few-layer SnS/CH3NH3PbI3 heterostructures and its effects on electronic and optical properties by density functional theory...
November 26, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29170599/complexity-and-challenges-in-noncontact-high-temperature-measurements-in-microwave-assisted-catalytic-reactors
#16
Lalit S Gangurde, Guido S J Sturm, Tushar J Devadiga, Andrzej I Stankiewicz, Georgios D Stefanidis
The complexity and challenges in noncontact temperature measurements inside microwave-heated catalytic reactors are presented in this paper. A custom-designed microwave cavity has been used to focus the microwave field on the catalyst and enable monitoring of the temperature field in 2D. A methodology to study the temperature distribution in the catalytic bed by using a thermal camera in combination with a thermocouple for a heterogeneous catalytic reaction (methane dry reforming) under microwave heating has been demonstrated...
November 15, 2017: Industrial & Engineering Chemistry Research
https://www.readbyqxmd.com/read/29166555/maximizing-catalysis-of-nanoparticles-via-their-monolayer-assembly-on-nitrogen-doped-graphene
#17
Chao Yu, Xuefeng Guo, Mengqi Shen, Bo Shen, Michelle Muzzio, Zhouyang Yin, Qing Li, Zheng Xi, Junrui Li, Christopher Takakazu Seto, Shouheng Sun
We report a facile interface assembly method to assemble a monolayer array of nitrogen-doped graphene (NG) and nanoparticles (NPs) and then to transfer the dual monolayers onto a solid substrate. Using 3 nm NiPd NPs as an example, we demonstrate that NiPd-NG-Si can function as a catalyst probe and show maximum NiPd catalysis for the hydrolysis of ammonia borane (H3NBH3, AB) with its TOF = 4896.8 h-1 and Ea = 18.8 kJ/mol. The NiPd-NG-Si is also highly active for catalyzing the synthesis of quinazolines in water, only 0...
November 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29152972/defect-engineering-in-mose2-for-hydrogen-evolution-reaction-from-point-defects-to-edges
#18
Haibo Shu, Dong Zhou, Feng Li, Dan Cao, Xiaoshuang Chen
Superior catalytic activity and high chemical stability of inexpensive electrocatalysts for the hydrogen evolution reaction (HER) are crucial to the large-scale production of hydrogen from water. The nonprecious two-dimensional (2D) MoSe2 materials are emerged as a potential candidate, and the improvement of their catalytic activity depends on the optimization of active reaction sites at both the edges and the basal plane. Herein, the structural stability, electrocatalytic activity and HER mechanisms on a series of MoSe2 catalytic structures including of point defects, holes, and edges have been explored by using first-principles calculations...
November 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29136586/generalised-two-dimensional-correlation-analysis-of-the-co-ce-and-pd-mixed-oxide-catalytic-systems-for-methane-combustion-using-in-situ-infrared-spectroscopy
#19
Damian K Chlebda, Przemysław J Jodłowski, Roman J Jędrzejczyk, Joanna Łojewska
The process of methane combustion over the surface of a catalyst is still not fully understood. The identification of the reaction path and the intermediates created during catalysis is crucial for understanding the transformation of methane molecules. Two-dimensional (2D) correlation spectroscopy was engaged as a tool for the quantitative analysis of a series of temperature-dependent infrared spectra registered in situ during methane combustion. The prepared samples of catalysts were based on a Co, Pd and Ce mixed oxide adsorbed on an aluminium oxide layer deposited on kanthal steel...
November 8, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29124369/exploring-the-regioselectivity-in-the-cycloaddition-of-azides-to-alkynes-catalyzed-by-dinuclear-copper-clusters-cu2aac-reaction-using-the-topologies-of-%C3%A2-2-%C3%AF-r-and-%C3%A2-%C3%A2-2-%C3%AF-r
#20
S Calvo-Losada, J J Quirante
The regioselectivity of the dinuclear-Cu(I)-catalyzed version of the Huisgen reaction, abbreviated in this paper to Cu2AAC, was analyzed using quantum topological methods in order to study how the electronic charge distribution evolved along different reaction paths. Electronic densities were computed at the LC-wPBE/6-311++G(2d,2p)//LC-wPBE/6-311++G(d,p) level. The presence of two copper ions in the catalyst was found to lead to an electrophilic site in the external alkyne carbon that, in a generalized Sharpless-type mechanism, undergoes an initial donor-acceptor interaction with the azide molecule, but with an inverted electrophile-nucleophile pattern when compared with the corresponding mononuclear process (CuAAC)...
November 9, 2017: Journal of Molecular Modeling
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