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nano catalysis

Huanchen Zhai, Anastassia N Alexandrova
Sub-nano surface-supported catalytic clusters, can be generally characterized by many low-energy isomers accessible at elevated temperatures of catalysis. The most stable isomer may not be the most catalytically active. Additionally, isomers may interconvert across barriers, i.e. exhibit fluxionality, during catalysis. To study the big picture of the cluster fluxional behavior, we model such a process as isomerization graph using bipartite matching algorithm, harmonic transition state theory, and paralleled nudged elastic band method...
March 18, 2018: Journal of Physical Chemistry Letters
David Portehault, Simon Delacroix, Guillaume Gouget, Rémi Grosjean, Tsou-Hsi-Camille Chan-Chang
The design of inorganic nanoparticles relies strongly on the knowledge from solid-state chemistry not only for characterization techniques, but also and primarily for choosing the systems that will yield the desired properties. The range of inorganic solids reported and studied as nanoparticles is however strikingly narrow when compared to the solid-state chemistry portfolio of bulk materials. Efforts to enlarge the collection of inorganic particles are becoming increasingly important for three reasons. First, they can yield materials more performing than current ones for a range of fields including biomedicine, optics, catalysis, and energy...
March 13, 2018: Accounts of Chemical Research
Wojciech Ogieglo, Bader S Ghanem, Xiao-Hua Ma, Matthias Wessling, Ingo Pinnau
Ultra-thin microporous polymer films are pertinent to the development and further spread of nanotechnology with very promising potential applications in molecular separations, sensors, catalysis or batteries. Here, we report high pressure CO2 sorption in ultra-thin films of several chemically different polymers of intrinsic microporosity (PIMs), including the prototypical PIM-1. Films with thicknesses down to 7 nm were studied using interference-enhanced in-situ spectroscopic ellipsometry. It was found that all PIMs swell much more than non-microporous polystyrene and other high performance glassy polymers reported previously...
March 12, 2018: ACS Applied Materials & Interfaces
Pandeeswar Makam, Ehud Gazit
Molecular self-assembly is a ubiquitous process in nature and central to bottom-up nanotechnology. In particular, the organization of peptide building blocks into ordered supramolecular structures has gained much interest due to the unique properties of the products, including biocompatibility, chemical and structural diversity, robustness and ease of large-scale synthesis. In addition, peptides, as short as dipeptides, contain all the molecular information needed to spontaneously form well-ordered structures at both the nano- and the micro-scale...
March 2, 2018: Chemical Society Reviews
Sen Lin, Shiyong Sun, Ke Wang, Kexuan Shen, Biaobiao Ma, Yuquan Ren, Xiaoyu Fan
The bioinspired design and construction of enzyme@capsule microreactors with specific cell-like functionality has generated tremendous interest in recent years. Inspired by their fascinating complexity, scientists have endeavored to understand the essential aspects of a natural cell and create biomimicking microreactors so as to immobilize enzymes within the hierarchical structure of a microcapsule. In this study, simultaneous encapsulation of alcohol dehydrogenase (ADH) was achieved during the preparation of microcapsules by the Pickering emulsion method using amphiphilic modified TiO₂ nanoparticles (NPs) as building blocks for assembling the photocatalytic microcapsule membrane...
February 24, 2018: Nanomaterials
Sisi Dai, Bin Quan, Xiaohui Liang, Jing Lv, Zhihong Yang, Youwei Du, Guangbin Ji
Nowadays, more and more interests have been devoted in artificial design and functional nanostructures for its application prospects in catalysis, drug delivery, energy storage and microwave absorption. With the advantages of natural abundance, low cost and environment friendliness, one-dimensional (1D) MnO2 nanowire (MWs) is the representative dielectric-loss absorber for its special morphology and crystalline structure. However, low reflection loss (RL) value at the thin thickness limits its wide development and application in the microwave absorption field...
February 23, 2018: Nanotechnology
Bo Tang, Jiannan Du, Qingmao Feng, Jiaqi Zhang, Dan Wu, Xiankai Jiang, Ying Dai, Jinlong Zou
Anodic electro-catalysis oxidation is a highly effective way to solve the pollution problem of antibiotics in wastewater and receiving water bodies. In this study, for the first time, molybdenum trioxide/Nano-graphite (MoO3/Nano-G) composites are synthesized as anodic catalysts by a surfactant-assisted solvothermal method followed by low-temperature calcination. The effects of the proportion of MoO3 to Nano-G (10, 30 and 50%) on the properties of composites are investigated through structural characterizations and electrochemical measurements...
January 31, 2018: Journal of Colloid and Interface Science
Thomas Hartman, Bert M Weckhuysen
Raman spectroscopy is known as a powerful technique for solid catalyst characterization as it provides vibrational fingerprints of (metal) oxides, reactants, and products. It can even become a strong surface-sensitive technique by implementing shell-isolated surface-enhanced Raman spectroscopy (SHINERS). Au@TiO2 and Au@SiO2 shell-isolated nanoparticles (SHINs) of various sizes were therefore prepared for the purpose of studying heterogeneous catalysis and the effect of metal oxide coating. Both SiO2 - and TiO2 -SHINs are effective SHINERS substrates and thermally stable up to 400 °C...
February 1, 2018: Chemistry: a European Journal
Piyush Kumar Verma, Mahadev L Shegavi, Shubhankar Kumar Bose, K Geetharani
Herein, we present a chronological survey of the metal/metal oxide nanoparticle-catalysed borylation reactions. Transition metal-catalysed borylation is considered to be one of the most efficient methods for the synthesis of organoboron derivatives. Considering chemical and pharmaceutical processes, the major drawbacks of homogeneous catalysis are metal contamination in products and inability to recover catalysts for reuse, which limit its application industrially, in biomolecules, and materials science. The use of nanoparticles as heterogeneous catalysts is a current topic of research to overcome these limitations...
January 30, 2018: Organic & Biomolecular Chemistry
Wenqiang Li, Ibrahim Saana Amiinu, Bei Ye, Zhe Wang, Jiawei Zhu, Zongkui Kou, Shichun Mu
Currently, the multicomponent Pt-based alloy as promising electrocatalyst has been applied to improve the catalysis and lower the usage of noble metal Pt. Herein, we report on a Te nanowire (NW) derived ternary TePtFe nanotube (NT) electrocatalyst prepared by the Kirkendall effect. The formed TePtFe NT consisting of small single crystal nanoparticles and voids with the open-end and hollow structure, presents ultrahigh catalytic activity and stability for both oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER)...
January 29, 2018: ChemSusChem
Zhihong Wang, Fenhui Cao, Kongfa Chen, Yingming Yan, Yifu Chen, Yaohui Zhang, Xingbao Zhu, Bo Wei, Yueping Xiong, Zhe Lv
Cellular metals with the large surface-to-volume ratios and excellent electrical conductivity are widely applicable and have thus been studied extensively. It is highly desirable to develop a facile and cost-effective process for fabrication of porous metallic structures, more so for micron/nano pores. Herein, we propose a novel direct-flame strategy for in-situ fabrication of micron cellular architecture on Ni metal precursor. The flame provides required heat, but also serves as a fuel reformer providing a gas mixture of H2, CO and O2 for redox treatment of Ni metals...
January 10, 2018: ChemSusChem
Jeremy Cure, Hala Assi, Kévin Cocq, Lorena Marín, Katia Fajerwerg, Pierre Fau, Eric Beche, Yves J Chabal, Alain Esteve, Carole Rossi
The integration of high-purity nano-objects on substrates remains a great challenge for addressing scaling-up issues in nanotechnology. For instance, grafting gold nanoparticles (NPs) on zinc oxide films, a major step process for catalysis or photovoltaic applications, still remains difficult to master. We report a modified photo-deposition (P-D) approach that achieves tight control of the NPs size (7.5 ± 3 nm), shape (spherical), purity, and high areal density (3500 ± 10 NPs/m2) on ZnO films. This deposition method is also compatible with large ZnO surface areas...
January 9, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Alla Malinenko, Alban Jonchere, Luc Girard, Sandra Parrès-Maynadié, Olivier Diat, Pierre Bauduin
Owing to their multiple charges and their nanometric size polyoxometalates (POMs) are at the frontier between ions and charged colloids. We investigated here the effect of POM-POM electrostatics repulsions on their self-diffusion in water by varying POM and supporting salt concentrations. The self-diffusion coefficients of two Keggin's POMs: silicotungstate (SiW4-) and phosphotungstate (PW3-) were determined by dynamic light scattering (DLS) and DOSY 1H/31P NMR whereas POM-POM electrostatic repulsions were investigated by the determination of the static structure factors using small angle X-ray scattering (SAXS)...
December 26, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Thomas Cornell, Maziar S Ardejani, Jing Fu, Stephanie Newland, Yu Zhang, Brendan P Orner
Cage proteins, which assemble into often highly symmetric hollow nano-scale capsules, have great potential in ap-plications as far reaching as drug delivery, hybrid nanomaterial engineering, and catalysis. In addition, they are promising model systems to understand how cellular nanostructures are constructed through protein-protein interactions, and they are beginning to be used as scaffolds for synthetic biology approaches. Recently, there has been renewed interest in the engineering of protein cages and, in support of these strategies, we have recently described a fluorescence-based assay for protein cage assembly that is specific for certain oligomerization states and symmetry-related protein-protein interfaces...
December 25, 2017: Biochemistry
Andi Cuko, Monica Calatayud, Stefan T Bromley
Nanostructured titanosilicate materials based upon interfacing nano-TiO2 with nano-SiO2 have drawn much attention due to their huge potential for applications in a diverse range of important fields including gas sensing, (photo)catalysis, solar cells, photonics/optical components, tailored multi-(bio)functional supports and self-cleaning coatings. In each case it is the specific mixed combination of the two SiO2 and TiO2 nanophases that determines the unique properties of the final nanomaterial. In the bulk, stoichiometric mixing of TiO2 with SiO2 is limited by formation of segregated TiO2 nanoparticles or metastable glassy phases and more controlled disperse crystalline mixings only occur at small fractions of TiO2 (<15 wt%)...
December 20, 2017: Nanoscale
Siddharth Gautam, Thu Le, Alberto Striolo, David Cole
Molecular motion under confinement has important implications for a variety of applications including gas recovery and catalysis. Propane confined in mesoporous silica aerogel as studied using quasielastic neutron scattering (QENS) showed anomalous pressure dependence in its diffusion coefficient (J. Phys. Chem. C, 2015, 119, 18188). Molecular dynamics (MD) simulations are often employed to complement the information obtained from QENS experiments. Here, we report an MD simulation study to probe the anomalous pressure dependence of propane diffusion in silica aerogel...
December 13, 2017: Physical Chemistry Chemical Physics: PCCP
Dong Yang, Jingjing Zhao, Jiafu Shi, Xueyan Wang, Shaohua Zhang, Zhongyi Jiang
Graphene-based materials with hierarchical structures and multifunctionality have gained much interest in a variety of applications. Herein, we report a facile, yet universal approach to prepare graphene-based composite cellular foams (GCCFs) through combination of redox assembly and biomimetic mineralization enabled by cationic polymers. Specifically, cationic polymers (e.g., polyethyleneimine, lysozyme, etc.) could not only reduce and simultaneously assemble graphene oxide (GO) into cellular foams but also confer the cellular foams with mineralization-inducing capability, enabling the formation of inorganic nanoparticles (e...
December 20, 2017: ACS Applied Materials & Interfaces
Maria Wadsäter, Justas Barauskas, Fredrik Tiberg, Tommy Nylander
The effects of different lipolytic enzymes on the structure of lipid liquid crystalline nano-particles (LCNP) have been investigated by cryogenic transmission electron microscopy (cryo-TEM) and synchrotron small angle X-ray diffraction (SAXD). Here we used highly structured cubic micellar (Fd3m) nanoparticles of 50/50 (wt%/wt%) soy phosphatidyl choline (SPC)/glycerol dioleate (GDO) as substrate. Two types of lipolytic enzymes were used, phospholipase A2 (PLA2) that catalysis degradation of the phospholipid component, SPC, and porcine pancreatic triacylglycerol lipase (TGL) that facilitate the hydrolysis of the diglyceride, GDO...
November 10, 2017: Chemistry and Physics of Lipids
Weiyi Zhang, Qiang Zhao, Jiayin Yuan
The past decade has witnessed rapid advances in porous polyelectrolytes and there is tremendous ongoing interest in their synthesis and applications in environment, energy, biomedicine and catalysis. The porous polyelectrolytes research is motivated by the synergy of, apart from the flexible choice of functional organic groups and processing technologies, the charge and pores spanning length scales from individual polyelectrolyte backbones to their nano/micro superstructures. This review surveys recent progresses on porous polyelectrolytes including membranes, particles, scaffolds, high surface area powders/resins, and their derivatives...
November 9, 2017: Angewandte Chemie
Silvia A Blank-Shim, Sebastian P Schwaminger, Monika Borkowska-Panek, Priya Anand, Peyman Yamin, Paula Fraga-García, Karin Fink, Wolfgang Wenzel, Sonja Berensmeier
Magnetic nanoparticles (MNP) are intensively investigated for applications in nanomedicine, catalysis and biotechnology, where their interaction with peptides and proteins plays an important role. However, the characterisation of the interaction of individual amino acids with MNP remains challenging. Here, we classify the affinity of 20 amino acid homo-hexamers to unmodified iron oxide nanoparticles using peptide arrays in a variety of conditions as a basis to identify and rationally design selectively binding peptides...
October 25, 2017: Scientific Reports
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