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2D catalyst

Vivekanand Sharma, Dinesh De, Sanchari Pal, Prithwidip Saha, Parimal K Bharadwaj
The solvothermal reaction of Zn(NO3)2·6H2O and a linear dicarboxylate ligand H2L, in the presence of urotropine in N,N'-dimethylformamide (DMF), gives rise to a new porous two-dimensional (2D) coordination network, {[Zn3(L)3(urotropine)2]·2DMF·3H2O}n (1), with hxl topology. Interestingly, framework 1 exhibits excellent emission properties owing to the presence of naphthalene moiety in the linker H2L, that can be efficiently suppressed by subtle quantity of nitro explosives in aqueous medium. Furthermore, presence of urotropine molecules bound to the metal centers, 1 is found to be an excellent heterogeneous catalyst meant for atom-economical C-C bond-forming Baylis-Hillman reactions...
July 21, 2017: Inorganic Chemistry
Biswajit Choudhury, Pravat Kumar Giri, Rajender Gone
This work spotlights the development of a plasmonic photocatalyst showing surface plasmon induced enhanced visible light photocatalytic performance. Plasmonic Au nanoparticles (NPs) are decorated over the hybrid nanosystem of graphitic carbon nitride (GCN) and graphene quantum dots (GQD) by citrate reduction method. Surface plasmon resonance (SPR) induced enhancement of Raman G and 2D band intensity is encountered on excitation of the Plasmonic hybrid at 514.5 nm, which is near to the 532 nm absorption band of Au nanoparticles...
July 20, 2017: Nanotechnology
Dechao Geng, Xiaoxu Zhao, Zhongxin Chen, Weiwei Sun, Wei Fu, Jianyi Chen, Wei Liu, Wu Zhou, Kian Ping Loh
As a new member of the MXene group, 2D Mo2 C has attracted considerable interest due to its potential application as electrodes for energy storage and catalysis. The large-area synthesis of Mo2 C film is needed for such applications. Here, the one-step direct synthesis of 2D Mo2 C-on-graphene film by molten copper-catalyzed chemical vapor deposition (CVD) is reported. High-quality and uniform Mo2 C film in the centimeter range can be grown on graphene using a Mo-Cu alloy catalyst. Within the vertical heterostructure, graphene acts as a diffusion barrier to the phase-segregated Mo and allows nanometer-thin Mo2 C to be grown...
July 19, 2017: Advanced Materials
Jing Fu, Fathy M Hassan, Cheng Zhong, Jun Lu, Han Liu, Aiping Yu, Zhongwei Chen
A critical bottleneck limiting the performance of rechargeable zinc-air batteries lies in the inefficient bifunctional electrocatalysts for the oxygen reduction and evolution reactions at the air electrodes. Hybridizing transition-metal oxides with functional graphene materials has shown great advantages due to their catalytic synergism. However, both the mediocre catalytic activity of metal oxides and the restricted 2D mass/charge transfer of graphene render these hybrid catalysts inefficient. Here, an effective strategy combining anion substitution, defect engineering, and the dopant effect to address the above two critical issues is shown...
July 17, 2017: Advanced Materials
Aurelie Anais Simone Rovetta, Michelle Phillippa Browne, Andrew Harvey, Ian James Godwin, Jonathan N Coleman, Michael Edward Graeme Lyons
Finding alternative routes to access and store energy has become a major issue recently. Transition metal oxides have shown promising behaviour as catalysts and supercapacitors. Recently, liquid exfoliation of bulk metal oxides appears to be an effective route which provides access to 2-dimensional (2D) nano-flakes, the size of which can be easily selected. These 2D materials exhibit excellent electrochemical charge storage and catalytic activity for the oxygen evolution reaction. In this study, various size selected cobalt hydroxide nano-flake materials are fabricated by this time efficient and highly reproducible process...
July 11, 2017: Nanotechnology
José I Santos, Úrsula Fillat, Raquel Martín-Sampedro, María E Eugenio, María J Negro, Ignacio Ballesteros, Alejandro Rodríguez, David Ibarra
In modern lignocellulosic-based biorefineries, carbohydrates can be transformed into biofuels and pulp and paper, whereas lignin is burned to obtain energy. However, a part of lignin could be converted into value-added products including bio-based aromatic chemicals, as well as building blocks for materials. Then, a good knowledge of lignin is necessary to define its valorisation procedure. This study characterized different lignins from side-streams produced from olive tree pruning bioethanol production (lignins collected from steam explosion pretreatment with water or phosphoric acid as catalysts, followed by simultaneous saccharification and fermentation process) and alkaline pulping (lignins recovered from kraft and soda-AQ black liquors)...
July 6, 2017: International Journal of Biological Macromolecules
Catherine R Rajamathi, Uttam Gupta, Koushik Pal, Nitesh Kumar, Hao Yang, Yan Sun, Chandra Shekhar, Binghai Yan, Stuart Parkin, Umesh V Waghmare, Claudia Felser, C N R Rao
As one of the major areas of interest in catalysis revolves around 2D materials based on molybdenum sulfide, we have examined the catalytic properties of bismuth selenides and tellurides which are among the first chalcogenides to be proven as topological insulators (TIs). We find significant photochemical H₂ evolution activity with these TIs as catalysts. H₂ evolution increases drastically in nanosheets of Bi₂Te₃ compared to single crystals. First-principles calculations show that due to the topology, surface states participate and promote the hydrogen evolution...
July 6, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Ruizhe Wu, Jie Pan, Xuewu Ou, Qicheng Zhang, Yao Ding, Ping Sheng, Zhengtang Luo
The synthesis of large-domain-sized graphene requires a low nucleation density, which inevitably leads to a reduced growth rate. To achieve both a large domain size and high growth rate, we designed a simple channel structure that allowed us to control the nucleation density by tuning the flow dynamics and by introducing an additional catalyst inside to control the growth kinetics at the same time. The designed channel structure plays three roles in the growth of graphene: (1) it retains oxygen to passivate the active nucleation sites; (2) it restricts the mass transfer of CH4 to control the supersaturation for nucleation; and (3) it provides additional catalytic sites for the decomposition of CH4 to boost the graphene growth rate...
July 13, 2017: Nanoscale
Lauro Oliver Paz-Borbón, Andres López-Martínez, Ignacio L Garzón, Alvaro Posada-Amarillas, Henrik Grönbeck
Transition metal particles dispersed on oxide supports are used as heterogeneous catalysts in numerous applications. One example is platinum clusters supported on ceria which is used in automotive catalysis. Although control at the nm-scale is desirable to open new technological possibilities, there is limited knowledge both experimentally and theoretically regarding the geometrical structure and stability of sub-nanometer platinum clusters supported on ceria. Here we report a systematic, Density Functional Theory (DFT) study on the growth trends of CeO2(111) supported PtN clusters (N = 1-10)...
July 21, 2017: Physical Chemistry Chemical Physics: PCCP
Ji-Soo Jang, Seon-Jin Choi, Won-Tae Koo, Sang-Joon Kim, Jun Young Cheong, Il-Doo Kim
Room-temperature (RT) operation sensors are constantly in increasing demand because of their low power consumption, simple operation, and long lifetime. However, critical challenges such as low sensing performance, vulnerability under highly humid state, and poor recyclability hinder their commercialization. In this work, sub-10 nm hollow, bimetallic Pt-Ag nanoparticles (NPs) were successfully formed by galvanic replacement reaction in bioinspired hollow protein templates and sensitized on the multidimensional SnO2-WO3 heterojunction nanofibers (HNFs)...
July 14, 2017: ACS Applied Materials & Interfaces
Christophe Copéret, Wei-Chih Liao, Christopher P Gordon, Ta-Chung Ong
Development of well-defined heterogeneous catalysts requires detailed structural characterization of active sites, an essential step toward establishing structure-activity relationships and promoting rational designs of catalysts. Solid-state NMR has emerged as a powerful approach to provide key molecular-level information about active-site structures and dynamics in heterogeneous catalysis. Here, we describe how one can apply solid-state NMR, ranging from 1D chemical shift assignments (and additional parameters, CQ and η, for quadrupolar nuclei, I > (1)/2) to 2D correlations, to analysis of chemical shift anisotropy, providing unprecedented structural information about a broad range of materials...
July 17, 2017: Journal of the American Chemical Society
Wang Zhang, Kun Zhou
Water oxidation, also known as the oxygen evolution reaction (OER), is a crucial process in energy conversion and storage, especially in water electrolysis. The critical challenge of the electrochemical water splitting technology is to explore alternative precious-metal-free catalysts for the promotion of the kinetically sluggish OER. Recently, emerging two-dimensional (2D) ultrathin materials with abundant accessible active sites and improved electrical conductivity provide an ideal platform for the synthesis of promising OER catalysts...
June 28, 2017: Small
Anirban Karmakar, Guilherme M D M Rúbio, Anup Paul, M Fátima C Guedes da Silva, Kamran T Mahmudov, Firudin I Guseinov, Sónia A C Carabineiro, Armando J L Pombeiro
Five isostructural lanthanide MOFs, [Ln(1κOO',2κO'',3κO''',4κO''''-μ4-L)(NO3)(DMF)2]n·n(DMF) {Ln = La(3+) (1), Ce(3+) (2), Nd(3+) (3), Sm(3+) (4) and Dy(3+) (5); L = 5-[2-{2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene}hydrazinyl]isophthalate; DMF = N,N'-dimethyl formamide}, based on dicarboxyl-functionalized arylhydrazone of barbituric acid were synthesized under solvothermal conditions. They were characterized by elemental analysis, FT-IR spectroscopy, thermogravimetric and X-ray diffraction analyses...
June 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Dianming Wang, Guoliang Zhang, Yiyang Zhang, Ling Xin, Yuanchen Dong, Yang Liu, Dongsheng Liu
Membrane plays significant role in cellular enzymatic reactions. To better understand its function on membrane integral or bound enzymes, DNA origami and frame-guided assembly strategy are combined to construct a given-size, addressable enzyme-containing nanomembrane as a heterogeneous reactor to explore the enzymatic catalyst reaction on the membrane. The enzymes in the membrane are located precisely. This new kind of membrane can enrich hydrophobic substrate molecules in aqueous solution to the embedded enzymes...
June 22, 2017: Small
Hao Li, Jie Li, Zhihui Ai, Falong Jia, Lizhi Zhang
Semiconductor photocatalysis is a trustworthy approach to harvest clean solar light for energy conversions, while state-of-the-art catalytic efficiencies are unsatisfactory because of the finite light response and/or robust charge carriers' recombination. Along with the development of modern material characterization techniques and electronic-structure computations, oxygen vacancies (OVs) on real photocatalysts surface, even in infinitesimal concentration, are found to play a more decisive role in determining the kinetics, energetics and mechanisms of photocatalytic reactions...
June 20, 2017: Angewandte Chemie
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
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
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
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 29, 2017: Nanoscale
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
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