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2D catalyst

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https://www.readbyqxmd.com/read/28627553/evans-showell-type-polyoxometalate-constructing-novel-3d-inorganic-architectures-with-alkaline-earth-metal-linkers-syntheses-structures-and-catalytic-properties
#1
Yujiao Hou, Haiyan An, Baojun Ding, Yanqin Li
Four new architectures containing [Co2Mo10H4O38](6-) polyoxoanions, (C2N2H10)2[Sr(H2O)5][Co2Mo10H4O38]·2H2O 1, (C2N2H10)2[Ba(H2O)3][Co2Mo10H4O38]·3H2O 2, (C3N2H12)2[Sr(H2O)5][Co2Mo10H4O38]·3H2O 3 and (C3N2H12)[Ba(H2O)4][Ba(H2O)4][Co2Mo10H4O38]·2H2O 4 (C2N2H10 = ethylenediamine; C3N2H12 = 1,3-propanediamine) have been synthesized and characterized by elemental analysis, IR spectroscopy, solid diffuse reflective spectroscopy, TG analysis, powder X-ray diffraction and single crystal X-ray diffraction. Compounds 1 and 2 obtained in the presence of ethylenediamine, are made of Evans-Showell-type anions [Co2Mo10H4O38](6-), linked by Sr(2+) or Ba(2+) cations to form 3D frameworks...
June 19, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28623744/obtaining-sparse-distributions-in-2d-inverse-problems
#2
A Reci, A J Sederman, L F Gladden
The mathematics of inverse problems has relevance across numerous estimation problems in science and engineering. L1 regularization has attracted recent attention in reconstructing the system properties in the case of sparse inverse problems; i.e., when the true property sought is not adequately described by a continuous distribution, in particular in Compressed Sensing image reconstruction. In this work, we focus on the application of L1 regularization to a class of inverse problems; relaxation-relaxation, T1-T2, and diffusion-relaxation, D-T2, correlation experiments in NMR, which have found widespread applications in a number of areas including probing surface interactions in catalysis and characterizing fluid composition and pore structures in rocks...
May 25, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28614750/2d-cos-of-in-situ-%C3%AE-raman-and-in-situ-ir-spectra-for-structure-evolution-characterisation-of-nep-deposited-cobalt-oxide-catalyst-during-n-nonane-combustion
#3
Damian K Chlebda, Przemysław J Jodłowski, Roman J Jędrzejczyk, Joanna Łojewska
New catalytic systems are still in development to meet the challenge of regulations concerning the emission of volatile organic compounds (VOCs). This is because such compounds have a significant impact on air quality and some of them are toxic to the environment and human beings. The catalytic combustion process of VOCs over non-noble metal catalysts is of great interest to researchers. The high conversion parameters and cost effective preparation makes them a valuable alternative to monoliths and noble metal catalysts...
June 6, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28608902/ultrathin-co3o4-nanofilm-as-an-efficient-bifunctional-catalyst-for-oxygen-evolution-and-reduction-reaction-in-rechargeable-zinc-air-batteries
#4
Yu He, Jinfeng Zhang, Guowei He, Xiaopeng Han, Xuerong Zheng, Cheng Zhong, Wenbin Hu, Yida Deng
Two-dimensional (2D) nanocatalysts with a large specific surface area and efficient charge conductivity are promising candidates for catalyzing the sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), which are at the heart of various electrochemical energy conversion and storage technologies. Here, we report the synthesis of an ultrathin Co3O4 nanofilm with a thickness of nearly 1.8 nm via a surfactant- and template-free facile hydrothermal route. The proposed synthesis strategy can be extended to the preparation of 2D NixCo3-xO4 and FexCo3-xO4 nanostructures...
June 13, 2017: Nanoscale
https://www.readbyqxmd.com/read/28595005/3d-porphyrin-based-covalent-organic-frameworks
#5
Guiqing Lin, Huimin Ding, Rufan Chen, Zhengkang Peng, Baoshan Wang, Cheng Wang
The design and synthesis of three-dimensional covalent organic frameworks (3D COFs) bearing photoelectric units have been considered as a big challenge. Herein, for the first time, we reported the targeted synthesis of two 3D porphyrin-based COFs (3D-Por-COF and 3D-CuPor-COF), starting from tetrahedral (3D-Td) and square (2D-C4) building blocks connected through [4 + 4] imine condensation reactions. On the basis of structural characterizations, 3D-Por-COF and 3D-CuPor-COF are microporous materials with high surface areas, and are proposed to adopt a 2-fold interpenetrated pts topology with Pmc21 space group...
June 15, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28593650/delocalized-spin-states-in-2d-atomic-layers-realizing-enhanced-electrocatalytic-oxygen-evolution
#6
Shichuan Chen, Zhixiong Kang, Xin Hu, Xiaodong Zhang, Hui Wang, Junfeng Xie, XuSheng Zheng, Wensheng Yan, Bicai Pan, Yi Xie
The electrocatalytic activity of transition-metal-based compounds is strongly related to the spin states of metal atoms. However, the ways for regulation of spin states of catalysts are still limited, and the underlying relationship between the spin states and catalytic activities remains unclear. Herein, for the first time, by taking Ni(II) -based compounds without high or low spin states for example, it is shown that their spin states can be delocalized after introducing structural distortion to the atomic layers...
June 8, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28581557/a-porous-two-dimensional-zn-ii-coordination-polymer-exhibiting-sc-sc-transmetalation-with-cu-ii-efficient-heterogeneous-catalysis-for-the-henry-reaction-and-detection-of-nitro-explosives
#7
Mayank Gupta, Dinesh De, Sanchari Pal, Tapan K Pal, Kapil Tomar
The linker 5-(benzylamino)isophthalic acid (H2L) forms a robust 2D Zn(ii)-coordination polymer, {[Zn8(L)6(μ3-OH)4(H2O)6]·(DMF)·(H2O)2.5}n(1Zn) consisting of [Zn4(μ3-OH)2](6+) SBUs. It further shows strong ππ interactions between the layers to form an overall 3D structure with well-defined channels. Metal bound water molecules are directed towards these channels. Upon heating, these metal bound water molecules are lost along with lattice solvent molecules to afford coordinatively unsaturated metal centers that can be utilized as an efficient heterogeneous catalyst for the C-C bond forming nitroaldol or Henry reaction...
June 13, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28574398/controllable-and-scalable-synthesis-of-ordered-mesoporous-silica-nanosheets-by-using-acidified-g-c3n4-as-a-lamellar-surfactant
#8
Xiaorui Du, Guojun Zou, Xiaolai Wang
Two-dimensional (2D) mesoporous nanomaterial is required in catalysis, separation, adsorption, and energy storage fields due to its outstanding mass transfer performance. However, its fabrication via "bottom up" strategy has been rarely reported and is limited by the difficulties in obtaining versatile and accessible structure-directing agent. Here ultrathin mesoporous silica nanosheets (MSN) were successfully synthesized by employing acidified g-C3N4 as a structural directing agent owing to its natural layered structure, stoichiometric solubility, and amphiphilicity...
June 2, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28567265/competitive-coordination-strategy-for-the-synthesis-of-hierarchical-pore-metal-organic-framework-nanostructures
#9
Su He, Yifeng Chen, Zhicheng Zhang, Bing Ni, Wei He, Xun Wang
Metal-organic frameworks (MOFs) usually have micropores smaller than 2 nm, which may restrict their applications in some cases. Hierarchical-pore MOFs (H-MOFs) are a new family of MOF materials, possessing both micro- and mesopores to address this problem. Here we demonstrate a competitive coordination strategy for the synthesis of H-MOF nanostructures, such as two-dimensional (2D) H-MOF nanosheets and H-MOF nanocubes, evolving through an etching process tuned by a competitive ligand. The as-synthesized 2D H-MOF nanosheets can serve as a substrate to in situ immobilize Pd nanoparticles to achieve a surfactant-free Pd catalyst, by means of a simple soaking method of Pd(2+) precursors...
December 1, 2016: Chemical Science
https://www.readbyqxmd.com/read/28556383/2d-porous-carbons-prepared-from-layered-organic-inorganic-hybrids-and-their-use-as-oxygen-reduction-electrocatalysts
#10
Shuang Li, Chong Cheng, Hai-Wei Liang, Xinliang Feng, Arne Thomas
2D porous carbon nanomaterials have attracted tremendous attention in different disciplines especially for electrochemical catalysis. The significant advantage of such 2D materials is that nearly all their surfaces are exposed to the electrolyte and can take part in the electrochemical reaction. Here, a versatile active-salt-templating strategy to efficiently synthesize 2D porous carbon nanosheets from layered organic-inorganic hybrids is presented. The resulting heteroatom-doped carbon nanosheets (NFe/CNs) exhibit exceptional performance for the oxygen-reduction reaction and in Zn-air battery electrodes...
May 29, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28544425/free-standing-holey-ni-oh-2-nanosheets-with-enhanced-activity-for-water-oxidation
#11
Xiangkai Kong, Changlin Zhang, Sang Youp Hwang, Qianwang Chen, Zhenmeng Peng
Electrochemical water oxidation is the key technology in water-splitting reactions and rechargeable metal-air batteries, which is very attractive for renewable energy conversion and storage. Replacement of precious catalysts with cost-effective and highly active alternatives is still a great challenge. Herein, based on theoretical predictions, holey structures are designed and fabricated on the free-standing conventional 2D OER catalyst. By well-controlled defects engineering, uniform tiny holes are created on the free-standing Ni(OH)2 nanosheets via a sol-gel method, with the embedded Zn components as the template for holes production...
May 19, 2017: Small
https://www.readbyqxmd.com/read/28541654/stable-1t-mose2-and-carbon-nanotube-hybridized-flexible-film-binder-free-and-high-performance-li-ion-anode
#12
Ting Xiang, Shi Tao, Weiyu Xu, Qi Fang, Chuanqiang Wu, Daobin Liu, Yu Zhou, Adnan Khalil, Zahir Muhammad, Wangsheng Chu, Zhonghui Wang, Hongfa Xiang, Qin Liu, Li Song
Two-dimensional stable metallic 1T-MoSe2 with expanded interlayer spacing of 10.0 Å in situ grown on SWCNTs film is fabricated via a one-step solvothermal method. Combined with X-ray absorption near-edge structures, our characterization reveals that such 1T-MoSe2 and single-walled carbon nanotubes (abbreviated as 1T-MoSe2/SWCNTs) hybridized structure can provide strong electrical and chemical coupling between 1T-MoSe2 nanosheets and SWCNT film in a form of C-O-Mo bonding, which significantly benefits a high-efficiency electron/ion transport pathway and structural stability, thus directly enabling high-performance lithium storage properties...
June 6, 2017: ACS Nano
https://www.readbyqxmd.com/read/28537721/multivariate-chiral-covalent-organic-frameworks-with-controlled-crystallinity-and-stability-for-asymmetric-catalysis
#13
Jie Zhang, Xing Han, Xiaowei Wu, Yan Liu, Yong Cui
The modular construction of covalent organic frameworks (COFs) provides a convenient platform for designing high-performance functional materials, but the synthetic control over their chirality has been relatively barely studied. Here we report a multivariate strategy to prepare chiral COFs (CCOFs) with controlled crystallinity and stability for asymmetric catalysis. By crystallizing mixtures of triamines with and without chiral organocatalysts and with a dialdehyde, a family of two- and three-component 2D porous CCOFs that adopt two different stacking modes is prepared...
June 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28533413/confined-catalysis-under-two-dimensional-materials
#14
Haobo Li, Jianping Xiao, Qiang Fu, Xinhe Bao
Confined microenvironments formed in heterogeneous catalysts have recently been recognized as equally important as catalytically active sites. Understanding the fundamentals of confined catalysis has become an important topic in heterogeneous catalysis. Well-defined 2D space between a catalyst surface and a 2D material overlayer provides an ideal microenvironment to explore the confined catalysis experimentally and theoretically. Using density functional theory calculations, we reveal that adsorption of atoms and molecules on a Pt(111) surface always has been weakened under monolayer graphene, which is attributed to the geometric constraint and confinement field in the 2D space between the graphene overlayer and the Pt(111) surface...
June 6, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28521090/ultrafast-vibrational-energy-transfer-in-catalytic-monolayers-at-solid-liquid-interfaces
#15
Jan Philip Kraack, Angelo Frei, Roger Alberto, Peter Hamm
We investigate the ultrafast vibrational dynamics of monolayers from adsorbed rhenium-carbonyl CO2-reduction catalysts on a semiconductor surface (indium-tin-oxide (ITO)) with ultrafast two-dimensional attenuated total reflection infrared (2D ATR IR) spectroscopy. The complexes are partially equipped with isotope-labeled ((13)C) carbonyl ligands to generate two spectroscopically distinguishable forms of the molecules. Ultrafast vibrational energy transfer between the molecules is observed via the temporal evolution of cross-peaks between their symmetric carbonyl stretching vibrations...
May 22, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28514161/interdiffusion-reaction-assisted-hybridization-of-two-dimensional-metal-organic-frameworks-and-ti3c2tx-nanosheets-for-electrocatalytic-oxygen-evolution
#16
Li Zhao, Biliang Dong, Shaozhou Li, Lijun Zhou, Linfei Lai, Zhiwei Wang, Shulin Zhao, Min Han, Kai Gao, Min Lu, Xiaoji Xie, Bo Chen, Zhengdong Liu, Xiangjing Wang, Hao Zhang, Hai Li, Juqing Liu, Hua Zhang, Xiao Huang, Wei Huang
Two-dimensional (2D) metal-organic framework (MOF) nanosheets have been recently regarded as the model electrocatalysts due to their porous structure, fast mass and ion transfer through the thickness, and large portion of exposed active metal centers. Combining them with electrically conductive 2D nanosheets is anticipated to achieve further improved performance in electrocatalysis. In this work, we in situ hybridized 2D cobalt 1,4-benzenedicarboxylate (CoBDC) with Ti3C2Tx (the MXene phase) nanosheets via an interdiffusion reaction-assisted process...
May 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28509363/ni-fe-nitride-nanoplates-on-nitrogen-doped-graphene-as-a-synergistic-catalyst-for-reversible-oxygen-evolution-reaction-and-rechargeable-zn-air-battery
#17
Yuchi Fan, Shintaro Ida, Aleksandar Staykov, Taner Akbay, Hidehisa Hagiwara, Junko Matsuda, Kenji Kaneko, Tatsumi Ishihara
Obtaining bifunctional electrocatalysts with high activity for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is a main hurdle in the application of rechargeable metal-air batteries. Earth-abundant 3d transition metal-based catalysts have been developed for the OER and ORR; however, most of these are based on oxides, whose insulating nature strongly restricts their catalytic performance. This study describes a metallic Ni-Fe nitride/nitrogen-doped graphene hybrid in which 2D Ni-Fe nitride nanoplates are strongly coupled with the graphene support...
May 16, 2017: Small
https://www.readbyqxmd.com/read/28497954/metallic-two-dimensional-nanoframes-unsupported-hierarchical-nickel-platinum-alloy-nanoarchitectures-with-enhanced-electrochemical-oxygen-reduction-activity-and-stability
#18
Fernando Godínez-Salomón, Rubén Mendoza-Cruz, M Josefina Arellano-Jimenez, Miguel Jose-Yacaman, Christopher P Rhodes
Electrochemical oxygen reduction reaction (ORR) catalysts that have both high activities and long-term stabilities are needed for proton-exchange membrane fuel cells (PEMFCs) and metal-air batteries. Two-dimensional (2D) materials based on graphene have shown high catalytic activities, however, carbon-based materials result in significant catalyst degradation due to carbon oxidation that occurs at high electrochemical potentials. Here, we introduce the synthesis and electrochemical performance of metallic 2D nanoframes which represent a new approach to translate 2D materials into unsupported (carbon-free) electrocatalysts that have both significantly higher ORR catalytic activities and stabilities compared with conventional Pt/carbon electrocatalysts...
June 7, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28493513/metal-free-poly-cycloaddition-of-activated-azide-and-alkynes-toward-multifunctional-polytriazoles-aggregation-induced-emission-explosive-detection-fluorescent-patterning-and-light-refraction
#19
Yongwei Wu, Benzhao He, Changyun Quan, Chao Zheng, Haiqin Deng, Rongrong Hu, Zujin Zhao, Fei Huang, Anjun Qin, Ben Zhong Tang
The metal-free click polymerization (MFCP) of activated alkynes and azides or activated azide and alkynes have been developed into powerful techniques for the construction of polytriazoles without the obsession of metallic catalyst residues problem. However, the MFCP of activated azides and alkynes is rarely applied in preparation of functional polytriazoles. In this paper, soluble multifunctional polytriazoles (PIa and PIb) with high weight-average molecular weights (Mw up to 32 000) are prepared via the developed metal-free poly-cycloaddition of activated azide and alkynes in high yields (up to 90%)...
May 11, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28493381/nitrogen-doped-graphitic-porous-carbons-derived-from-in-situ-formed-g-c3n4-templates-for-oxygen-reduction-reaction
#20
Feng Yan, Qi Li, Dan Xu, Xu Ou
Heteroatom-doped carbon materials have been considered as substitutes of Pt-based electrocatalysts for oxygen reduction reaction (ORR) in alkaline fuel cells. Here, we reported the synthesis of oxygen-containing nitrogen-doped carbon (ONC) nanosheets via the carbonization of a mixture containing glucose and dicyandiamide (DCDA). In situ formed graphitic carbon nitride (g-C3N4) derived from DCDA provides a nitrogen-rich template, facilitating the formation of ONC nanosheets. The resultant ONC materials with high nitrogen contents, high specific surface areas, and mesoporous total volume displayed the excellent electrochemical performances, including a similar ORR onset potential, half-potential, a higher diffusion-limited current and excellent tolerance to methanol than that of the commercial Pt/C catalyst, respectively...
May 11, 2017: Chemistry, An Asian Journal
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