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2D catalyst

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https://www.readbyqxmd.com/read/28447692/pillar-5-arene-based-1-rotaxane-high-yield-synthesis-characterization-and-application-in-knoevenagel-reaction
#1
Xu-Sheng Du, Chun-Yu Wang, Qiong Jia, Rong Deng, Hua-Sheng Tian, Hou-Yu Zhang, Kamel Meguellati, Ying-Wei Yang
We report a quantitative synthetic strategy of a [1]rotaxane from a representative pseudo[1]rotaxane. The structure of the [1]rotaxane was characterized by (1)H NMR, (13)C NMR, 2D NMR, mass spectroscopy, and melting point, and its optimized geometry in CHCl3 by theoretical calculation at the B3LYP/6-31G(D) level using the PCM model matched well with 2D NOESY. This [1]rotaxane proves to be a good catalyst for the Knoevenagel reaction in CHCl3, which follows second order kinetics.
April 27, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28422235/a-facile-mechanochemical-route-to-a-covalently-bonded-graphitic-carbon-nitride-g-c3n4-and-fullerene-hybrid-toward-enhanced-visible-light-photocatalytic-hydrogen-production
#2
Xiang Chen, Huanlin Chen, Jian Guan, Jieming Zhen, Zijun Sun, Pingwu Du, Yalin Lu, Shangfeng Yang
Graphitic carbon nitride (g-C3N4) as an emerging two-dimensional (2D) nanomaterial has been commonly used as a metal-free photocatalyst with potential applications in visible light photocatalytic water-splitting. However, the photocatalytic activity of g-C3N4 is quite low due to its relatively large band gap and the existence of contact resistance between the nanosheets. Herein we report for the first time the facile synthesis of a covalently bonded g-C3N4/C60 hybrid via a solid-state mechanochemical route and its application in photocatalytic hydrogen production under visible light...
April 19, 2017: Nanoscale
https://www.readbyqxmd.com/read/28421210/more-accurate-depiction-of-adsorption-energy-on-transition-metals-using-work-function-as-one-additional-descriptor
#3
Xiaochen Shen, Yanbo Pan, Bin Liu, Jinlong Yang, Jie Zeng, Zhenmeng Peng
The reaction mechanism and properties of a catalytic process are primarily determined by the interactions between reacting species and catalysts. However, the interactions are often challenging to be experimentally measured, especially for unstable intermediates. Therefore, it is of significant importance to establish an exact relationship between chemical-catalyst interactions and catalyst parameters, which will allow calculation of these interactions and thus advance their mechanistic understanding. Herein we report the description of adsorption energy on transition metals by considering both ionic bonding and covalent bonding contributions and introduce the work function as one additional responsible parameter...
April 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28414421/shape-controlled-metal-free-catalysts-facet-sensitive-catalytic-activity-induced-by-the-arrangement-pattern-of-noncovalent-supramolecular-chains
#4
Guangwei Geng, Penglei Chen, Bo Guan, Lang Jiang, Zhongfei Xu, Dawei Di, Zeyi Tu, Weichang Hao, Yuanping Yi, Chuncheng Chen, Minghua Liu, Wenping Hu
Metal-free catalytic materials have recently received broad attention as promising alternatives to metal-involved catalysts. This is owing to their inherent capability to overcome the inevitable limitations of metal-involved catalysts, such as high sensitivity to poisoning, the limited reserves, high cost and scarcity of metals (especially noble metals), etc. However, the lack of shape-controlled metal-free catalysts with well-defined facets is a formidable bottleneck limiting our understandings on the underlying structure-activity relationship at atomic/molecular level, which thereby restrains their rational design...
April 19, 2017: ACS Nano
https://www.readbyqxmd.com/read/28397299/0d-2d-quantum-dot-metal-dichalcogenide-nanocomposite-photocatalyst-achieves-efficient-hydrogen-generation
#5
Xiao-Yuan Liu, Hao Chen, Ruili Wang, Yuequn Shang, Qiong Zhang, Wei Li, Guozhen Zhang, Juan Su, Cao Thang Dinh, F Pelayo García de Arquer, Jie Li, Jun Jiang, Qixi Mi, Rui Si, Xiaopeng Li, Yuhan Sun, Yi-Tao Long, He Tian, Edward H Sargent, Zhijun Ning
Hydrogen generation via photocatalysis-driven water splitting provides a convenient approach to turn solar energy into chemical fuel. The development of photocatalysis system that can effectively harvest visible light for hydrogen generation is an essential task in order to utilize this technology. Herein, a kind of cadmium free Zn-Ag-In-S (ZAIS) colloidal quantum dots (CQDs) that shows remarkably photocatalytic efficiency in the visible region is developed. More importantly, a nanocomposite based on the combination of 0D ZAIS CQDs and 2D MoS2 nanosheet is developed...
April 11, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28387508/solvent-induced-assembly-of-sliver-coordination-polymers-cps-as-cooperative-catalysts-for-synthesizing-of-cyclopentenone-b-pyrroles-frameworks
#6
Chao Huang, Xiao Han, ZhiChao Shao, Kuan Gao, Mengjia Liu, Yanjie Wang, Jie Wu, Hongwei Hou, Liwei Mi
A series of solvent-induced Ag-based coordination polymers (CPs) (1-3), which were synthesized by regulating the size, shape, and polarity of solvent molecules (EtOH, iPrOH, 1,4-dioxane) as structure-directing agents, has been used as heterogeneous catalysts to explore how the metal-metal bonds could serve as cooperative catalysis for tandem acylation-Nazarov cyclization reaction to prepare cyclopentenone[b]pyrroles frameworks. Structural conversions from a three-dimensional (3D) framework of 1 to the structure of 2 with Ag-Ag-Ag bonds and to the two-dimensional (2D) framework of 3 with Ag-Ag bonds, arising from the different sizes, shapes, and polarities of the solvent molecules, were observed...
April 7, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28383186/fabrication-of-micropatterned-self-oscillating-polymer-brush-for-direction-control-of-chemical-waves
#7
Kenta Homma, Tsukuru Masuda, Aya Mizutani Akimoto, Kenichi Nagase, Kazuyoshi Itoga, Teruo Okano, Ryo Yoshida
The propagation control of chemical waves via a pentagonal patterned structure in a self-oscillating polymer brush composed of N-isopropylacrylamide and a metal catalyst for the Belousov-Zhabotinsky (BZ) reaction is reported. The patterned self-oscillating polymer brush is prepared by combining surface-initiated atom transfer radical polymerization and maskless photolithography. Surface modification is confirmed by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, 3D measuring laser microscopy, and fluorescence microscopy...
April 6, 2017: Small
https://www.readbyqxmd.com/read/28374538/high-efficiency-green-and-scalable-%C3%AE-cyclodextrin-assisted-aqueous-exfoliation-of-transition-metal-dichalcogenides-the-cases-of-mos2-and-res2
#8
Wancheng Zhao, Xingxing Tan, Jingyun Jiang, Feijie Liu, Tiancheng Mu
β-cyclodextrin-assisted aqueous-exfoliation method is successfully introduced to prepare transition metal dichalcogenides nanosheets (TMDs), which is cheap, high-efficiency, scalable, and environmentally friendly. As the cases, MoS2 and ReS2 nanoflakes are prepared using our method. Particularly, the effective exfoliation of ReS2 crystal in aqueous environment is demonstrated for the first time. Moreover, exfoliated nanomaterials can be availably utilized in hydrogen evolution reaction (HER) as noble-metal-free catalyst...
April 3, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28368105/triazolyl-imidazolyl-and-carboxylic-acid-moieties-in-the-design-of-molybdenum-trioxide-hybrids-photophysical-and-catalytic-behavior
#9
Andrey B Lysenko, Ganna A Senchyk, Konstantin V Domasevitch, Merten Kobalz, Harald Krautscheid, Jakub Cichos, Miroslaw Karbowiak, Patrícia Neves, Anabela A Valente, Isabel S Gonçalves
Three organic ligands bearing 1,2,4-triazolyl donor moieties, (S)-4-(1-phenylpropyl)-1,2,4-triazole (trethbz), 4-(1,2,4-triazol-4-yl)benzoic acid (trPhCO2H), and 3-(1H-imidazol-4-yl)-2-(1,2,4-triazol-4-yl)propionic acid (trhis), were prepared to evaluate their coordination behavior in the development of molybdenum(VI) oxide organic hybrids. Four compounds, [Mo2O6(trethbz)2]·H2O (1), [Mo4O12(trPhCO2H)2]·0.5H2O (2a), [Mo4O12(trPhCO2H)2]·H2O (2b), and [Mo8O25(trhis)2(trhisH)2]·2H2O (3), were synthesized and characterized...
April 3, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28345908/rapid-low-temperature-formation-of-imine-linked-cofs-catalyzed-by-metal-triflates
#10
Michio Matsumoto, Raghunath R Dasari, Woojung Ji, Cameron H Feriante, Timothy C Parker, Seth R Marder, William R Dichtel
Imine-linked two-dimensional covalent organic frameworks (2D COFs) are crystalline polymer networks with enhanced stability and broader monomer scope compared to boronate ester-linked systems. They are traditionally prepared by condensing polyfunctional aldehydes and amines at elevated temperature in a mixture of organic solvents and aqueous CH3CO2H, which catalyzes imine formation and exchange. Under these conditions, an amorphous imine-linked polymer network precipitates quickly and then crystallizes after extended reaction times (hours to days)...
March 27, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28291319/molybdenum-carbide-embedded-nitrogen-doped-porous-carbon-nanosheets-as-electrocatalysts-for-water-splitting-in-alkaline-media
#11
Chenbao Lu, Diana Tranca, Jian Zhang, Fermı N Rodrı Guez Hernández, Yuezeng Su, Xiaodong Zhuang, Fan Zhang, Gotthard Seifert, Xinliang Feng
Molybdenum carbide (Mo2C) based catalysts were found to be one of the most promising electrocatalysts for hydrogen evolution reaction (HER) in acid media in comparison with Pt-based catalysts but were seldom investigated in alkaline media, probably due to the limited active sites, poor conductivity, and high energy barrier for water dissociation. In this work, Mo2C-embedded nitrogen-doped porous carbon nanosheets (Mo2C@2D-NPCs) were successfully achieved with the help of a convenient interfacial strategy. As a HER electrocatalyst in alkaline solution, Mo2C@2D-NPC exhibited an extremely low onset potential of ∼0 mV and a current density of 10 mA cm(-2) at an overpotential of ∼45 mV, which is much lower than the values of most reported HER electrocatalysts and comparable to the noble metal catalyst Pt...
April 25, 2017: ACS Nano
https://www.readbyqxmd.com/read/28282138/synthesis-of-small-molecule-dna-hybrids-through-on-bead-amide-coupling-approach
#12
Kenji D Okochi, Luca Monfregola, Sarah Michelle Dickerson, Ryan McCaffrey, Dylan W Domaille, Chao Yu, Glenn R Hafenstine, Yinghua Jin, Jennifer N Cha, Robert D Kuchta, Marvin Caruthers, Wei Zhang
Small molecule/DNA hybrids (SMDHs) have been considered as nanoscale building blocks for engineering 2D and 3D supramolecular DNA assembly. Herein, we report an efficient on-bead amide-coupling approach to prepare SMDHs with multiple oligodeoxynucleotide (ODN) strands. Our method is high yielding under mild and user-friendly conditions with various organic substrates and homo- or mixed-sequenced ODNs. Metal catalysts and moisture- and air-free conditions are not required. The products can be easily analyzed by LC-MS with accurate mass resolution...
March 20, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28267317/nanocomposites-of-c3n4-with-layers-of-mos2-and-nitrogenated-rgo-obtained-by-covalent-cross-linking-synthesis-characterization-and-her-activity
#13
K Pramoda, U Gupta, M Chhetri, A Bandyopadhyay, S K Pati, C N R Rao
Generation of hydrogen by photochemical, electrochemical, and other means is a vital area of research today, and a variety of materials have been explored as catalysts for this purpose. C3N4, MoS2, and nitrogenated RGO (NRGO) are some of the important catalytic materials investigated for the hydrogen evolution reaction (HER) reaction, but the observed catalytic activities are somewhat marginal. Prompted by preliminary reports that covalent cross-linking of 2D materials to generate heteroassemblies or nanocomposites may have beneficial effect on the catalytic activity, we have synthesized nanocomposites wherein C3N4 is covalently bonded to MoS2 or NRGO nanosheets...
March 29, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28251997/transfer-free-graphene-growth-on-sio2-substrate-at-250%C3%A2-%C3%A2-c
#14
Riteshkumar Vishwakarma, Mohamad Saufi Rosmi, Kazunari Takahashi, Yuji Wakamatsu, Yazid Yaakob, Mona Ibrahim Araby, Golap Kalita, Masashi Kitazawa, Masaki Tanemura
Low-temperature growth, as well as the transfer free growth on substrates, is the major concern of graphene research for its practical applications. Here we propose a simple method to achieve the transfer free graphene growth on SiO2 covered Si (SiO2/Si) substrate at 250 °C based on a solid-liquid-solid reaction. The key to this approach is the catalyst metal, which is not popular for graphene growth by chemical vapor deposition. A catalyst metal film of 500 nm thick was deposited onto an amorphous C (50 nm thick) coated SiO2/Si substrate...
March 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28208240/application-toward-confocal-full-field-microscopic-x-ray-absorption-near-edge-structure-spectroscopy
#15
Pieter Tack, Bart Vekemans, Brecht Laforce, Jennifer Rudloff-Grund, Willinton Y Hernández, Jan Garrevoet, Gerald Falkenberg, Frank Brenker, Pascal Van Der Voort, Laszlo Vincze
Using X-ray absorption near edge structure (XANES) spectroscopy, information on the local chemical structure and oxidation state of an element of interest can be acquired. Conventionally, this information can be obtained in a spatially resolved manner by scanning a sample through a focused X-ray beam. Recently, full-field methods have been developed to obtain direct 2D chemical state information by imaging a large sample area. These methods are usually in transmission mode, thus restricting the use to thin and transmitting samples...
February 7, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28195130/robust-microscale-superlubricity-under-high-contact-pressure-enabled-by-graphene-coated-microsphere
#16
Shu-Wei Liu, Hua-Ping Wang, Qiang Xu, Tian-Bao Ma, Gui Yu, Chenhui Zhang, Dechao Geng, Zhiwei Yu, Shengguang Zhang, Wenzhong Wang, Yuan-Zhong Hu, Hui Wang, Jianbin Luo
Superlubricity of graphite and graphene has aroused increasing interest in recent years. Yet how to obtain a long-lasting superlubricity between graphene layers, under high applied normal load in ambient atmosphere still remains a challenge but is highly desirable. Here, we report a direct measurement of sliding friction between graphene and graphene, and graphene and hexagonal boron nitride (h-BN) under high contact pressures by employing graphene-coated microsphere (GMS) probe prepared by metal-catalyst-free chemical vapour deposition...
February 14, 2017: Nature Communications
https://www.readbyqxmd.com/read/28168251/dimensional-heterostructures-of-1d-cds-2d-znin2s4-composited-with-2d-graphene-designed-synthesis-and-superior-photocatalytic-performance
#17
Qingyong Tian, Wei Wu, Jun Liu, Zhaohui Wu, Weijing Yao, Jin Ding, Changzhong Jiang
The development of photocatalysts with superior photoactivity and stability for the degradation of organic dyes is very important for environmental remediation. In this study, we have presented a multidimensional (1D and 2D) structured CdS/ZnIn2S4/RGO photocatalyst with superior photocatalytic performance. The CdS/ZnIn2S4 helical dimensional heterostructures (DHS) were prepared via a facile solvothermal synthesis method to facilitate the epitaxial growth of 2D ZnIn2S4 nanosheets on 1D CdS nanowires. Ultrathin 2D ZnIn2S4 nanosheets have grown uniformly and perpendicular to the surface of 1D CdS nanowires...
February 7, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28159455/application-of-1-h-and-27-al-magic-angle-spinning-solid-state-nmr-at-60khz-for-studies-of-au-and-au-ni-catalysts-supported-on-boehmite-alumina
#18
Piotr Paluch, Natalia Potrzebowska, Agnieszka M Ruppert, Marek J Potrzebowski
In this work for the first time we show the power of solid state NMR spectroscopy in structural analysis of alumina and catalysts supported on the alumina surface employing very fast (60kHz) magic angle spinning (MAS) technique. In the methodological part we demonstrate that under such MAS condition, cross-polarization (CP) from proton to aluminum is an efficient process when a very weak (27)Al RF field is applied. The mechanism of CP transfer and the Hartmann-Hahn (H-H) matching conditions were tested for (27)Al RF fields equal to 3...
January 26, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28151677/interferometric-2d-sum-frequency-generation-spectroscopy-reveals-structural-heterogeneity-of-catalytic-monolayers-on-transparent-materials
#19
Heather Vanselous, Ashley M Stingel, Poul B Petersen
Molecular monolayers exhibit structural and dynamical properties that are different from their bulk counterparts due to their interaction with the substrate. Extracting these distinct properties is crucial for a better understanding of processes such as heterogeneous catalysis and interfacial charge transfer. Ultrafast nonlinear spectroscopic techniques such as 2D infrared (2D IR) spectroscopy are powerful tools for understanding molecular dynamics in complex bulk systems. Here, we build on technical advancements in 2D IR and heterodyne-detected sum frequency generation (SFG) spectroscopy to study a CO2 reduction catalyst on nanostructured TiO2 with interferometric 2D SFG spectroscopy...
February 6, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28150913/facile-preparation-of-ultrathin-co3-o4-nanocarbon-composites-with-greatly-improved-surface-activity-as-a-highly-efficient-oxygen-evolution-reaction-catalyst
#20
Yanyan Chen, Jun Hu, Honglin Diao, Wenjing Luo, Yu-Fei Song
The efficient catalytic oxidation of water to dioxygen plays a significant role in solar fuel and artificial photosynthetic systems. It remains highly challenging to develop oxygen evolution reaction (OER) catalysts with high activity and low cost under mild conditions. Here, a new composite material is reported based on ultrathin 2D Co3 O4 nanosheets and reduced graphene oxides (rGO) by means of a one-pot hydrothermal strategy. The ultrathin Co3 O4 /rGO nanocomposite shows superior stability under alkaline conditions and exhibits an overpotential of 290 mV with a Tafel slope of 68 mA dec(-1) , which is much smaller than that of bare Co3 O4 catalyst...
February 2, 2017: Chemistry: a European Journal
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