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nano catalysis

Stavros Alexandros Theofanidis, Vladimir V Galvita, Christos Konstantopoulos, Hilde Poelman, Guy B Marin
The role of iron in view of its further utilization in chemical processes is presented, based on current knowledge of its properties. The addition of iron to a catalyst provides redox functionality, enhancing its resistance to carbon deposition. FeOx species can be formed in the presence of an oxidizing agent, such as CO₂, H₂O or O₂, during reaction, which can further react via a redox mechanism with the carbon deposits. This can be exploited in the synthesis of active and stable catalysts for several processes, such as syngas and chemicals production, catalytic oxidation in exhaust converters, etc...
May 17, 2018: Materials
Yuanyuan Liu, Yuhong Zhao, Yong Zhou, Xinli Guo, Zhongtao Chen, Weijie Zhang, Yao Zhang, Jian Chen, Zengmei Wang, Litao Sun, Tong Zhang
Noble metal nanoparticles (NPs) such as Au, Ag have shown many applications in the field of catalysis and sensing etc due to their excellent photoelectric properties. But agglomeration and low recovery rate are big problems for their applications. In this research, a novel Ag NPs/graphene (reduced graphene oxide)-loading loofah sponge (Ag NPs/RGO-LS) was synthesized through a one-step reduction method. Where the RGO is used as a nano-support with the high specific surface area and the high conductivity to prevent the agglomeration of Ag NPs and provide a conductive layer...
May 11, 2018: Nanotechnology
Taisiia Berestok, Pablo Guardia, Javier Blanco Portals, Sonia Estrade, Jordi Llorca, Francesca Peiró, Andreu Cabot, Stephanie L Brock
Colloidal nanocrystals (NCs) compete with molecular catalysts in the field of homogenous catalysis, offering an easier recyclability and a number of potentially advantageous functionalities, such as tunable band gaps, plasmonic properties or a magnetic moment. Using high throughput printing technologies, colloidal NCs can be also supported onto substrates to produce cost-effective electronic, optoelectronic, electrocatalytic and sensing devices. For both catalytic and technological application, NCs surface chemistry and supracrystal organization are key parameters determining final performance...
May 11, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Matthias Driess, Chakadola Panda, Prashanth Wilfried Menezes
The low-temperature synthesis of inorganic materials and their interfaces at the atomic and molecular level provides numerous opportunities for the design and improvement of inorganic materials in heterogeneous catalysis for sustainable chemical energy conversion or other energy-saving areas. Using suitable molecular precursors for functional inorganic nanomaterial synthesis allows for facile control over uniform particle size distribution, stoichiometry, and leads to desired chemical and physical properties...
May 7, 2018: Angewandte Chemie
Akbar Samadi, Henrik Klingberg, Liselotte Jauffred, Andreas Kjær, Poul Martin Bendix, Lene B Oddershede
Absorption of near infrared (NIR) light by metallic nanoparticles can cause extreme heating and is of interest for instance in cancer treatment since NIR light has a relatively large penetration depth into biological tissue. Here, we quantify the extraordinary thermoplasmonic properties of platinum nanoparticles and demonstrate their efficiency in photothermal cancer therapy. Although platinum nanoparticles are extensively used for catalysis, they are much overlooked in a biological context. Via direct measurements based on a biological matrix we show that individual irradiated platinum nanoparticles with diameters of 50-70 nm can easily reach surface temperatures up to 900 K...
May 2, 2018: Nanoscale
Songfang Zhao, Fei Han, Jinhui Li, Xiangying Meng, Wangping Huang, Duxia Cao, Guoping Zhang, Rong Sun, Ching-Ping Wong
Copper nanowires (CuNWs) are attracting a myriad of attention due to their preponderant electric conductivity, optoelectronic and mechanical properties, high electrocatalytic efficiency, and large abundance. Recently, great endeavors are undertaken to develop controllable and facile approaches to synthesize CuNWs with high dispersibility, oxidation resistance, and zero defects for future large-scale nano-enabled materials. Herein, this work provides a comprehensive review of current remarkable advancements in CuNWs...
April 30, 2018: Small
M Sendra, M Volland, T Balbi, R Fabbri, M P Yeste, J M Gatica, L Canesi, J Blasco
Over the last decades, the growth in nanotechnology has provoked an increase in the number of its applications and consumer products that incorporate nanomaterials in their formulation. Metal nanoparticles are released to the marine environment and they can interact with cells by colloids forces establish a nano-bio interface. This interface can be compatible or generate bioadverse effects to cells. The daily use of CeO2 nanoparticles (CeO2 NPs) in industrial catalysis, sunscreen, fuel cells, fuel additives and biomedicine and their potential release into aquatic environments has turned them into a new emerging pollutant of concern...
April 22, 2018: Aquatic Toxicology
Gregor Cevc, Ida Berts, Stefan F Fischer, Joachim O Rädler, Bert Nickel
Fluid fatty alcohols are believed to be nanostructured but broadly amorphous, i.e. non-crystalline, fluids and solvents, including the most popular fatty tissue mimetic: hydrated n-octanol (i.e., hydro-octanol). To check this premise, we studied dry octanol and hydro-octanol, as a model of relatively short fluid n-alkanols, with small angle X- rays scattering (SAXS). We also combined this alkanol with the matching alkane (i.e., octane) and with a common anti-inflammatory pain-killer, ketoprofen. This revealed that (hydro)octanol, and arguably any other short fatty alcohol, forms a mesophase...
April 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Bo Zhang, Fanshu Meng, Jiangang Feng, Jingxia Wang, Yuchen Wu, Lei Jiang
The assembly of nanoparticles into ordered 3D architectures, which requires more complex spatial arrangements of nanoparticles than 2D, is essential to develop new nano- or microdevices in the fields of biotechnology, magnetic devices, catalysis, and optoelectronics. However, because of the long-distance interactions among the nanoparticles or the applied external force, the movement of nanoparticles cannot be precisely controlled, particularly in multidimensional architectures. Therefore, controlling the 3D architecture remains challenging...
April 23, 2018: Advanced Materials
Lifu Chen, Eden E L Tanner, Chuhong Lin, Richard G Compton
Graphene nanoplatelets are shown to electrocatalyse the oxidation of dopamine. Single entity measurements ('nano-impacts') coupled with microdisc voltammetry and UV-visible spectroscopy reveal that adsorption of dopamine and its oxidised product on the graphene nanoplatelets is the key factor causing the observed catalysis. Genetic implications are drawn both for the study of catalysts in general and for graphene nanoplatelets in particular.
January 7, 2018: Chemical Science
Giulio Fracasso, Paolo Ghigna, Luca Nodari, Stefano Agnoli, Denis Badocco, Paolo Pastore, Elena Nicolato, Pasquina Marzola, Dušan Mihajlović, Milan Markovic, Miodrag Čolić, Vincenzo Amendola
Laser ablation in liquid (LAL) emerged as a versatile technique for the synthesis of nanoparticles with various structures and compositions, although the control over products remains challenging in most cases. For instance, it is still difficult to drive the size of metal oxide crystalline domains down to the level of few atom clusters with LAL. Here we demonstrate that laser ablation of a bulk iron target in aqueous solution of phosphonates gives phosphonate-grafted iron oxo-clusters polymerized into nanoaggregates with Fe:ligand ratio of 2:1, instead of the usual nanocrystalline iron oxides...
March 20, 2018: Journal of Colloid and Interface Science
Ahed Zyoud, Maysaa Ateeq, Muath H Helal, Samer H Zyoud, Hikmat S Hilal
Photo-catalytic degradation of waste pharmaceutics, with solar radiation, is described here as a feasible method to purify pre-contaminated soils. Phenazopyridine has been used as a model soil contaminant. Two different nano-size powders have been first examined as catalysts, namely commercial TiO2 (anatase) and commercial ZnO. As the ZnO showed higher catalytic efficiency, the study was then focused on it. The commercial ZnO powder was then compared with lab-prepared ZnO powder, and the latter shows relatively higher efficiency...
March 30, 2018: Environmental Technology
Olga Naumov, Sergej Naumov, Bernd Abel, Aron Varga
A new approach in electrode catalysis bearing immense potential for electrochemical technologies is the prospect of carbon-based electrodes. Pristine carbon nanostructures are relatively inert and modifications like nitrogen doping are known for their beneficial effects on the electrochemical activity of carbon nanomaterials in both alkaline and acidic media. However, the long-term stability of these materials, especially in an acidic environment, is rarely mentioned. Here, we evaluate the stability and long-term degradation of nitrogen doped graphene flakes as an oxygen reduction electrocatalyst with theoretical and experimental techniques...
March 28, 2018: Nanoscale
Jianbo Tan, Qin Xu, Xueliang Li, Jun He, Yuxuan Zhang, Xiaocong Dai, Liangliang Yu, Ruiming Zeng, Li Zhang
Enzyme catalysis is a mild, efficient, and selective technique that has many applications in organic synthesis as well as polymer synthesis. Here, a novel enzyme-catalysis-induced reversible addition-fragmentation chain transfer (RAFT)-mediated dispersion polymerization for preparing AB diblock copolymer nano-objects with complex morphologies at room temperature is described. Taking advantage of the room-temperature feature, it is shown that pure, worm-like polymer nano-objects can be readily prepared by just monitoring the viscosity...
March 23, 2018: Macromolecular Rapid Communications
Josefredo R Pliego
Activation of potassium fluoride salt for selective and fast nucleophilic fluorination requires its solubilization and stabilization of the respective transition state. This goal can be achieved through control of the nano-environment around the reactants via cation or ion-pair binding catalysis. In this work, six different species were theoretically investigated as promoters and catalysts for nucleophilic fluorination: tri-tert-butanolamine, 18-crown-6, pentaethylene glycol, [2.2.2]-cryptand, and two new hydroxylated crown ethers (hydro-crowns)...
March 23, 2018: Organic & Biomolecular Chemistry
Avik Halder, Larry A Curtiss, Alessandro Fortunelli, Stefan Vajda
Size-selected clusters containing a handful of atoms may possess noble catalytic properties different from nano-sized or bulk catalysts. Size- and composition-selected clusters can also serve as models of the catalytic active site, where an addition or removal of a single atom can have a dramatic effect on their activity and selectivity. In this perspective, we provide an overview of studies performed under both ultra-high vacuum and realistic reaction conditions aimed at the interrogation, characterization, and understanding of the performance of supported size-selected clusters in heterogeneous and electrochemical reactions, which address the effects of cluster size, cluster composition, cluster-support interactions, and reaction conditions, the key parameters for the understanding and control of catalyst functionality...
March 21, 2018: Journal of Chemical Physics
Huanchen Zhai, Anastassia N Alexandrova
Subnano 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...
April 5, 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...
April 17, 2018: Accounts of Chemical Research
Wojciech Ogieglo, Bader Ghanem, Xiaohua Ma, Matthias Wessling, Ingo Pinnau
Ultrathin 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 ultrathin 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...
April 4, 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
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