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https://www.readbyqxmd.com/read/28915007/synthesis-and-properties-of-2d-carbon-graphdiyne
#1
Zhiyu Jia, Yongjun Li, Zicheng Zuo, Huibiao Liu, Changshui Huang, Yuliang Li
Graphdiyne (GDY) is a flat material comprising sp(2)- and sp-hybridized carbon atoms with high degrees of π conjugation that features uniformly distributed pores. It is interesting not only from a structural point of view but also from the perspective of its electronic, chemical, mechanical, and magnetic properties. We have developed an in situ homocoupling reaction of hexaethynylbenzene on Cu foil for the fabrication of large-area ordered films of graphdiyne. These films are uniform and composed of graphdiyne multilayers...
September 15, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28910096/finite-size-effects-in-sub-monolayer-catalysts-investigated-by-co-electrosorption-on-ptsml-pd-100
#2
Qiuyi Yuan, Hieu A Doan, Lars C Grabow, Stanko R Brankovic
A combination of scanning tunneling microscopy, subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS), and density functional theory (DFT) is used to quantify the local strain in 2D Pt clusters on the 100 facet of Pd and its effect on CO chemisorption. Good agreement between SNIFTIRS experiments and DFT simulations provide strong evidence that, in the absence of coherent strain between Pt and Pd, finite size effects introduce local compressive strain, which alters the chemisorption properties of the surface...
September 14, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28892617/understanding-of-electrochemical-mechanisms-for-co2-capture-and-conversion-into-hydrocarbon-fuels-in-transition-metal-carbides-mxenes
#3
Neng Li, Xingzhu Chen, Wee-Jun Ong, Douglas R MacFarlane, Xiujian Zhao, Anthony K Cheetham, Chenghua Sun
Two-dimensional (2D) transition-metal (groups IV, V, VI) carbides (MXenes) with formulas M3C2 have been investigated as CO2 conversion catalysts with well-resolved density functional theory calculations. While MXenes from the group IV to VI series have demonstrated an active behavior for the capture of CO2, the Cr3C2 and Mo3C2 MXenes exhibit the most promising CO2 to CH4 selective conversion capabilities. Our results predicted the formation of OCHO(•) and HOCO(•) radical species in the early hydrogenation steps through spontaneous reactions...
September 13, 2017: ACS Nano
https://www.readbyqxmd.com/read/28891263/superaerophobic-ultrathin-ni-mo-alloy-nanosheet-array-from-in-situ-topotactic-reduction-for-hydrogen-evolution-reaction
#4
Qian Zhang, Pengsong Li, Daojin Zhou, Zheng Chang, Yun Kuang, Xiaoming Sun
Hydrogen evolution reaction (HER) has prospect to becoming clean and renewable technology for hydrogen production and Ni-Mo alloy is among the best HER catalysts in alkaline electrolytes. Here, an in situ topotactic reduction method to synthesize ultrathin 2D Ni-Mo alloy nanosheets for electrocatalytic hydrogen evolution is reported. Due to its ultrathin structure and tailored composition, the as-synthesized Ni-Mo alloy shows an overpotential of 35 mV to reach a current density of 10 mA cm(-2) , along with a Tafel slope of 45 mV decade(-1) , demonstrating a comparable intrinsic activity to state-of-art commercial Pt/C catalyst...
September 11, 2017: Small
https://www.readbyqxmd.com/read/28880075/integrated-energy-aerogel-of-n-s-rgo-wse2-nife-ldh-for-both-energy-conversion-and-storage
#5
Xiaowei Xu, Hang Chu, Zhuqing Zhang, Pei Dong, Robert Baines, Pulickel M Ajayan, Jianfeng Shen, Mingxin Ye
High-performance active materials for energy-storage and energy-conversion applications require a novel class of electrodes: ones with a structure conducive to conductivity, large specific surface area, high porosity, and mechanical robustness. Herein, we report the design and fabrication of a new ternary hybrid aerogel. The process entails an in situ assembly of 2D WSe2 nanosheets and NiFe-LDH nanosheets on a 3D N,S-codoped graphene framework, accomplished by a facile hydrothermal method and electrostatic self-assembly technology...
September 15, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28876886/confined-catalysis-in-the-g-c3n4-pt-111-interface-feasible-molecule-intercalation-tunable-molecule-metal-interaction-and-enhanced-reaction-activity-of-co-oxidation
#6
Shujiao Wang, Yingxin Feng, Ming'an Yu, Qiang Wan, Sen Lin
The deposition of a two-dimensional (2D) atomic nanosheet on a metal surface has been considered as a new route for tuning the molecule-metal interaction and surface reactivity in terms of the confinement effect. In this work, we use first-principles calculations to systematically explore a novel nanospace constructed by placing a 2D graphitic carbon nitride (g-C3N4) nanosheet over a Pt(111) surface. The confined catalytic activity in this nanospace is investigated using CO oxidation as a model reaction. With the inherent triangular pores in the g-C3N4 overlayer being taken advantage of, molecules such as CO and O2 can diffuse to adsorb on the Pt(111) surface underneath the g-C3N4 overlayer...
September 15, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28875186/new-homoleptic-bis-pyrrolylpyridiylimino-mg-ii-and-zn-ii-complexes-as-catalysts-for-the-ring-opening-polymerization-of-cyclic-esters-via-an-activated-monomer-mechanism
#7
Ilaria D'Auria, Consiglia Tedesco, Mina Mazzeo, Claudio Pellecchia
The reaction of MgBu2 and ZnEt2 or Zn{N[Si(CH3)3]2}2 with a tridentate monoanionic pyrrolylpyridiylimino [N(-),N,N] proligand gave homoleptic species, as exclusive products, in high yields. The complexes were characterized in solution by 1D and 2D NMR analysis and by single crystal X-ray crystallography. The new homoleptic complexes were tested as initiators in the polymerization of ε-caprolactone and lactide in the presence of an exogenous alcohol. For both complexes, the polymerizations proceed via an "activated monomer" mechanism that, in the case of the magnesium complex, was correlated with the coordinative flexibility of the ligands, resulting in extremely high productivities under mild conditions...
September 6, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28859235/twinned-growth-of-metal-free-triazine-based-photocatalyst-films-as-mixed-dimensional-2d-3d-van-der-waals-heterostructures
#8
Dana Schwarz, Yu Noda, Jan Klouda, Karolina Schwarzová-Pecková, Ján Tarábek, Jiří Rybáček, Jiří Janoušek, Frank Simon, Maksym V Opanasenko, Jiří Čejka, Amitava Acharjya, Johannes Schmidt, Sören Selve, Valentin Reiter-Scherer, Nikolai Severin, Jürgen P Rabe, Petra Ecorchard, Junjie He, Miroslav Polozij, Petr Nachtigall, Michael J Bojdys
Design and synthesis of ordered, metal-free layered materials is intrinsically difficult due to the limitations of vapor deposition processes that are used in their making. Mixed-dimensional (2D/3D) metal-free van der Waals (vdW) heterostructures based on triazine (C3 N3 ) linkers grow as large area, transparent yellow-orange membranes on copper surfaces from solution. The membranes have an indirect band gap (Eg,opt = 1.91 eV, Eg,elec = 1.84 eV) and are moderately porous (124 m(2) g(-1) ). The material consists of a crystalline 2D phase that is fully sp(2) hybridized and provides structural stability, and an amorphous, porous phase with mixed sp(2) -sp hybridization...
August 31, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28855655/role-of-2d-and-3d-defects-on-the-reduction-of-lanio3-nanoparticles-for-catalysis
#9
Sarika Singh, Eric Prestat, Liang-Feng Huang, James M Rondinelli, Sarah J Haigh, Brian A Rosen
Solid phase crystallization offers an attractive route to synthesize Ni nanoparticles on a La2O3 support. These materials have shown great promise as catalysts for methane oxidation and similar reactions. Synthesis is achieved by the reduction of a LaNiO3 (LNO) precursor at high temperatures, but the reduction pathway can follow a variety of routes. Optimization of catalytic properties such as the long-term stability has been held back by a lack of understanding of the factors impacting the reduction pathway, and its strong influence on the structure of the resulting Ni/La2O3 catalyst...
August 30, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28853570/synthesis-of-2d-imine-linked-covalent-organic-frameworks-through-formal-transimination-reactions
#10
Edon Vitaku, William R Dichtel
Covalent organic frameworks (COFs) are crystalline, permanently porous, two-dimensional or three-dimensional polymers with tunable topology and functionali-ty. COFs linked with imines or β-ketoenamines are more chemically stable than their boron-linked counterparts, making them more promising for a broad range of applications, including energy storage devices, proton-conductive membranes, and catalyst supports. We report a general and scalable method for synthesizing imine- and β-ketoenamine-linked COFs based on the formal transimination of Ν-aryl benzophenone imines...
August 30, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28841308/palladium-ii-chloride-complexes-of-n-n-disubstituted-imidazole-2-thiones-syntheses-structures-and-catalytic-performances-in-suzuki-miyaura-and-sonogashira-coupling-reactions
#11
Li-Ming Zhang, Hai-Yan Li, Hong-Xi Li, David James Young, Yong Wang, Jian-Ping Lang
Reactions of PdCl2 with 2 equiv of N,N'-disubstituted-imidazole-2-thiones R(1)R(2)C3N2S (R(1) = R(2) = Me (1a), (i)Pr (1b), Cy (1c), C6Me3H2 (1d); R(1) = Me, R(2) = Ph (1e)) under the different conditions afford five mononuclear complexes trans-[(R(1)R(2)C3N2S)2PdCl2] (R(1) = R(2) = Me (2a), (i)Pr (2b), Cy (2c), C6Me3H2 (2d); R(1) = Me, R(2) = Ph (2e)) and five binuclear Pd(II) complexes [(PdCl2){μ-(R(1)R(2)C3N2S)}]2 (R(1) = R(2) = Me (3a), (i)Pr (3b), Cy (3c), C6Me3H2 (3d); R(1) = Me, R(2) = Ph (3e)), respectively...
August 25, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28830147/surface-sensitive-and-surface-specific-ultrafast-two-dimensional-vibrational-spectroscopy
#12
Jan Philip Kraack, Peter Hamm
Ultrafast two-dimensional infrared spectroscopy (2D IR) has been advanced in recent years toward measuring signals from only a monolayer of sample molecules at solid-liquid and solid-gas interfaces. A series of experimental methods has been introduced, which in the chronological order of development are 2D sum-frequency-generation (2D SFG), transmission 2D IR, and reflection 2D IR, the latter in either internal, attenuated total reflection (ATR), or external reflection configuration. The different variants of 2D vibrational spectroscopy are based on either the even-order or the odd-order nonlinear susceptibility, and all allow resolving similar molecular temporal and spectral information...
August 23, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28816406/phosphinous-acid-assisted-hydration-of-nitriles-understanding-the-controversial-reactivity-of-osmium-and-ruthenium-catalysts
#13
Rebeca González-Fernández, Pascale Crochet, Victorio Cadierno, M Isabel Menéndez, Ramón López
The synthesis and catalytic behaviour of the osmium(II) complexes [OsCl2(6-p-cymene)(PR2OH)] [R = Me (2a), Ph (2b), OMe (2c), OPh (2d)] in nitrile hydration reactions is presented. Among them, the best catalytic results were obtained with the phosphinous acid derivative [OsCl2(6-p-cymene)(PMe2OH)] (2a), which selectively provided the desired primary amides in excellent yields and short times at 80 ºC, employing directly water as solvent, and without the assistance of any basic additive (TOF values up to 200 h-1)...
August 17, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28812362/nitrogen-doped-porous-graphdiyne-a-highly-efficient-metal-free-electrocatalyst-for-oxygen-reduction-reaction
#14
Qing Lv, Wenyan Si, Ze Yang, Ning Wang, Zeyi Tu, Yuanping Yi, Changshui Huang, Li Jiang, Mingjia Zhang, Jianjiang He, Yunze Long
Metal-free catalysts for oxygen reduction reaction (ORR) are the desired materials for low-cost proton exchange membrane fuel cells. Graphdiyne (GDY), a novel type of two-dimensional carbon allotrope, is featured by its sp- and sp(2)-hybridized carbon atoms, different from the other existing carbon materials. Thus, nitrogen (N) can be doped in new styles by substituting sp-hybridized carbon atoms, effective for ORR, which has been displayed in this study using both experimental and theoretical technologies...
August 24, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28809428/a-critical-role-of-catalyst-morphology-in-low-temperature-synthesis-of-carbon-nanotube-transition-metal-oxide-nanocomposite
#15
Xiaoyan Jin, Joohyun Lim, Yoonhoo Ha, Nam Hee Kwon, Hyeyoung Shin, In Young Kim, Nam-Suk Lee, Myung Hwa Kim, Hyungjun Kim, Seong-Ju Hwang
The effect of the catalyst morphology on the growth of carbon nanotubes (CNT) on nanostructured transition metal oxides was investigated to study a novel low-temperature synthetic route to functional CNT-transition metal oxide nanocomposites. Among several nanostructured manganese oxides with various morphologies and structures, only exfoliated 2D nanosheets of layered MnO2 acted as an effective catalyst for the chemical vapor deposition of CNT at low temperatures of 400-500 °C, which emphasizes the critical role of the catalyst morphology in CNT growth...
August 31, 2017: Nanoscale
https://www.readbyqxmd.com/read/28790337/from-mechanistic-study-to-chiral-catalyst-optimization-theoretical-insight-into-binaphthophosphepine-catalyzed-asymmetric-intramolecular-3-2-cycloaddition
#16
Meng Duan, Lei Zhu, Xiaotian Qi, Zhaoyuan Yu, Yingzi Li, Ruopeng Bai, Yu Lan
Density functional M11 was used to study the mechanism and enantioselectivity of a binaphthophosphepine-catalyzed intramolecular [3 + 2] cycloaddition reaction. The computational results revealed that this reaction proceeds through nucleophilic addition of the phosphine catalyst to the allene, which yields a zwitterionic phosphonium intermediate. The subsequent stepwise [3 + 2] annulation process, which starts with the intramolecular nucleophilic addition of the allenoate moiety to the electron-deficient olefin group, determines the enantioselectivity of the reaction...
August 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28772558/synthesis-of-2d-nitrogen-doped-mesoporous-carbon-catalyst-for-oxygen-reduction-reaction
#17
Zhipeng Yu, Jinhua Piao, Zhenxing Liang
2D nitrogen-doped mesoporous carbon (NMC) is synthesized by using a mesoporous silica film as hard template, which is then investigated as a non-precious metal catalyst for the oxygen reduction reaction (ORR). The effect of the synthesis conditions on the silica template and carbon is extensively investigated. In this work, we employ dual templates-viz. graphene oxide and triblock copolymer F127-to control the textural features of a 2D silica film. The silica is then used as a template to direct the synthesis of a 2D nitrogen-doped mesoporous carbon...
February 17, 2017: Materials
https://www.readbyqxmd.com/read/28763581/surfactant-assisted-phase-selective-synthesis-of-new-cobalt-mofs-and-their-efficient-electrocatalytic-hydrogen-evolution-reaction
#18
Ya-Pan Wu, Wei Zhou, Jun Zhao, Wen-Wen Dong, Ya-Qian Lan, Dong-Sheng Li, Chenghua Sun, Xianhui Bu
Reported herein are two new polymorphic Co-MOFs (CTGU-5 and -6) that can be selectively crystallized into the pure 2D or 3D net using an anionic or neutral surfactant, respectively. Each polymorph contains a H2 O molecule, but differs dramatically in its bonding to the framework, which in turn affects the crystal structure and electrocatalytic performance for hydrogen evolution reaction (HER). Both experimental and computational studies find that 2D CTGU-5 which has coordinates water and more open access to the cobalt site has higher electrocatalytic activity than CTGU-6 with the lattice water...
August 1, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28762413/two-dimensional-covalent-organic-framework-materials-for-chemical-fixation-of-carbon-dioxide-excellent-repeatability-and-high-selectivity
#19
Kaikai Xu, Yihu Dai, Benfei Ye, Hongming Wang
Two dimensional (2D) metalloporphyrin-based covalent organic framework (COF) composites were synthesized and employed to catalyze the coupling of CO2 and epoxides to form cyclic carbonates. With the aid of a co-catalyst, a satisfactory selectivity (∼100%) and activity (99.2%) for the synthesis of 1,2-butylene carbonate were obtained on COF-366-Zn under mild reaction conditions. Their great recyclability and adaptability for various substrates were also demonstrated. The excellent performance may be benefited from their unique 2D COF structure and the facilitation effects on central metalloporphyrin sites from the internal environment of COFs...
August 22, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28758350/nanostructured-three-dimensional-3d-assembly-of-2d-mos2-and-graphene-directly-built-from-acidic-graphite-oxide
#20
Sunil P Lonkar, Vishnu V Pillai, Saeed Alhassan
A 3D highly interconnected macroporous network of reduced GO having finely dispersed few-layered 2D MoS2 nanosheets was constructed through direct use of acidic graphite oxide (GO) for the first time. This facile and technological scalable process can afford an efficient electrocatalysts, anode materials, HDS catalysts at lower cost and can circumvent the poor thermal stability and recyclability of the material. The strategy provided here can be the basis to design and develop practical processes to address the ultimate goal of large-scale manufacturing of hybrids composed of 2D materials for various energy and catalysis applications...
July 30, 2017: Chemistry, An Asian Journal
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