J. Heyrovsky Institute of Physical Chemistry

Prague, Czech Republic

J. Heyrovsky Institute of Physical Chemistry

Prague, Czech Republic
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Roth W.J.,J. Heyrovsky Institute of Physical Chemistry | Roth W.J.,Jagiellonian University | Nachtigall P.,Charles University | Morris R.E.,University of St. Andrews | Cejka J.,J. Heyrovsky Institute of Physical Chemistry
Chemical Reviews | Year: 2014

Zeolites are well-known as valuable crystalline solids with framework structures containing discrete micropores of molecular dimensions that accommodate exchangeable extra-framework cation sites. Lamellar zeolites combine useful benefits of both classes, high catalytic activity, microporosity, thermal stability, and chemical resistance of zeolites with structural flexibility of 2D solids, enabling their postsynthetic modification, both structural and compositional. The main category of 2D zeolites is the layered precursors, which are viewed as primary forms because they are the starting materials for further modifications. The various modifications may be an end product (IEZ-stabilized) or they may be further modifiable, like intercalated and swollen derivatives. Synthesis method, either via direct synthesis or by postsynthetic modification, is another criterion for classifying layered zeolite materials. New precursors can also be obtained from a regular zeolite by selective chemical degradation.

Spanel P.,J. Heyrovsky Institute of Physical Chemistry | Smith D.,Keele University
Mass Spectrometry Reviews | Year: 2011

The development of selected ion flow tube mass spectrometry, SIFT-MS, is described from its inception as the modified very large SIFT instruments used to demonstrate the feasibility of SIFT-MS as an analytical technique, towards the smaller but bulky transportable instruments and finally to the current smallest Profile 3 instruments that have been located in various places, including hospitals and schools to obtain on-line breath analyses. The essential physics and engineering principles are discussed, which must be appreciated to design and construct a SIFT-MS instrument. The versatility and sensitivity of the Profile 3 instrument is illustrated by typical mass spectra obtained using the three precursor ions H3O+, NO+ and O 2 +•, and the need to account for differential ionic diffusion and mass discrimination in the analytical algorithms is emphasized to obtain accurate trace gas analyses. The performance of the Profile 3 instrument is illustrated by the results of several pilot studies, including (i) on-line real time quantification of several breath metabolites for cohorts of healthy adults and children, which have provided representative concentration/population distributions, and the comparative analyses of breath exhaled via the mouth and nose that identify systemic and orally-generated compounds, (ii) the enhancement of breath metabolites by drug ingestion, (iii) the identification of HCN as a marker of Pseudomonas colonization of the airways and (iv) emission of volatile compounds from urine, especially ketone bodies, and from skin. Some very recent developments are discussed, including the quantification of carbon dioxide in breath and the combination of SIFT-MS with GC and ATD, and their significance. Finally, prospects for future SIFT-MS developments are alluded to. Copyright © 2010 Wiley Periodicals, Inc.

Kavan L.,J. Heyrovsky Institute of Physical Chemistry
Journal of Solid State Electrochemistry | Year: 2014

This article presents a critical discussion of selected structural aspects of electrochemical Li-insertion into TiO2 (anatase). Recent works are reviewed (almost half of the cited works is from 2010+) with a special attention to the crystal-face-specific phenomena, Raman spectroscopy, and single-crystal and nanocrystalline electrodes. The benefits of isotopic labeling are highlighted for the in-depth understanding of Raman spectra and the Raman spectroelectrochemistry of Li-insertion. The persisting open questions and contradictory issues in the field are discussed too. © 2014 Springer-Verlag Berlin Heidelberg.

Kavan L.,J. Heyrovsky Institute of Physical Chemistry
Topics in Current Chemistry | Year: 2014

Fullerenes, carbon nanotubes, nanodiamond, and graphene find various applications in the development of solar cells, including dye sensitized solar cells. Nanocarbons can be used as (1) active light-absorbing component, (2) current collector, (3) photoanode additive, or (4) counter electrode. Graphene-based materials have attracted considerable interest for catalytic counter electrodes, particularly in state-of-the-art dye sensitized solar cells with Co-mediators. The understanding of electrochemical charge-transfer at carbon surfaces is key to optimization of these solar cells, but the electrocatalysis on carbon surfaces is still a subject of conflicting debate. Due to the rich palette of problems at the interface of nanocarbons and photovoltaics, this review is selective rather than comprehensive. Its motivation was to highlight selected prospective inputs from nanocarbon science towards the development of novel dye sensitized solar cells with improved efficiency, durability, and cost. © 2014 Springer-Verlag Berlin Heidelberg.

Shestivska V.,J. Heyrovsky Institute of Physical Chemistry
Rapid communications in mass spectrometry : RCM | Year: 2011

Infection by Pseudomonas aeruginosa (PA) is a major cause of morbidity and mortality in patients with cystic fibrosis (CF). Breath analysis could potentially be a useful diagnostic of such infection, and analyses of volatile organic compounds (VOCs) emitted from PA cultures are an important part of the search for volatile breath markers of PA lung infection. Our pilot experiments using solid-phase microextraction, SPME and gas chromatography/mass spectrometric (GC/MS) analyses of volatile compounds produced by PA strains indicated a clear presence of methyl thiocyanate. This provided a motivation to develop a method for real-time online quantification of this compound by selected ion flow tube mass spectrometry, SIFT-MS. The kinetics of reactions of H(3)O(+), NO(+) and O(2)(+•) with methyl thiocyanate at 300K were characterized and the characteristic product ions determined (proton transfer for H(3)O(+), rate constant 4.6×10(-9) cm(3) s(-1); association for NO(+), 1.7×10(-9) cm(3) s(-1) and nondissociative charge transfer for O(2)(+•) 4.3×10(-9) cm(3) s(-1)). The kinetics library was extended by a new entry for methyl thiocyanate accounting for overlaps with isotopologues of hydrated hydronium ions. Solubility of methyl thiocyanate in water (Henry's law constant) was determined using standard reference solutions and the linearity and limits of detection of both SIFT-MS and SPME-GC/MS methods were characterized. Thirty-six strains of PA with distinct genotype were cultivated under identical conditions and 28 of them (all also producing HCN) were found to release methyl thiocyanate in headspace concentrations greater than 6 parts per billion by volume (ppbv). SIFT-MS was also used to analyze the breath of 28 children with CF and the concentrations of methyl thiocyanate were found to be in the range 2-21 ppbv (median 7 ppbv). Copyright © 2011 John Wiley & Sons, Ltd.

Samec Z.,J. Heyrovsky Institute of Physical Chemistry
Electrochimica Acta | Year: 2012

This note provides a brief account of the theoretical and experimental achievements in the study of the interface between two immiscible electrolytes, in particular of its structure and dynamics, and the charge transfer kinetics, including the most remarkable results that have been obtained in the last five years. Perspective topics for the future research in this area are outlined. © 2012 Elsevier Ltd.

Cejka J.,J. Heyrovsky Institute of Physical Chemistry
Topics in Catalysis | Year: 2010

This overview covers the recent achievements in the application of mesoporous molecular sieves as catalysts and catalyst supports. Main structural and textural features are outlined in relation to the novel synthesis approaches of mesoporous molecular sieves and understanding of their properties. For application of mesoporous molecular sieves as catalysts different ways of introduction of active sites on their surfaces are provided. The main part describes selected catalytic reactions catalyzed by mesoporous molecular sieves focused on very recent papers. The examples include metathesis, acylation reactions, C-C coupling reactions of Heck and Suzuki types, base-catalyzed reactions (Knoevenagel and Michael additions, Claisen-Schmidt condensation, Tischenko reaction) and last but not least immobilization of organometallic complexes for different catalytic applications including chiral catalysts. © 2009 Springer Science+Business Media, LLC.

Balcar H.,J. Heyrovsky Institute of Physical Chemistry | Cejka J.,J. Heyrovsky Institute of Physical Chemistry
Coordination Chemistry Reviews | Year: 2013

Mesoporous molecular silicas and aluminas based materials are excellent model supports for modification with catalytically active species for various organic reactions. They offer well-ordered structures, although of amorphous type, high BET areas, large mesopore volumes, and particularly the flexibility in the pore size adjustment. For application in metathesis, two principal ways of incorporation of catalytically active sites were investigated. The first one represents the modification with inorganic oxides (W, Mo, Re) while the second one is based on immobilization of organometallic complexes (Mo, Ru, W). This review discusses the preparation and properties of both types of heterogeneous catalysts and relates them to the activities, selectivities, and time-on-stream stabilities in different metathesis reactions. Particular attention is devoted to the role of mesoporous supports (textural properties, pore sizes and pore connectivities) as well as to catalyst recycling, real heterogeneous performance without any leaching of active species, and tolerance toward functional groups in the substrates under study. © 2013 Elsevier B.V.

Kresge C.T.,Dow Chemical Company | Roth W.J.,Jagiellonian University | Roth W.J.,J. Heyrovsky Institute of Physical Chemistry
Chemical Society Reviews | Year: 2013

By the combination of prior knowledge, observation skills, and novel synthetic approaches, we discovered a family of mesoporous molecular sieves including discrete structures-MCM-41 (hexagonal), MCM-48 (cubic), and MCM-50 (lamellar). These materials were formed unlike that of our classical microporous structures involving reagent induced-macromolecular templating mechanism. Based on synthetic data and working with others, we were able to establish a predictive mechanism of formation and identify a broad class of templating reagents. These initial findings generated great interest and effort worldwide. It resulted in tremendous expansion of knowledge and skills with many new additional discoveries that established a new area of ordered mesoporous materials. They are integrated with zeolites (microporous materials) and based on surfactant inorganic chemistry. © The Royal Society of Chemistry 2013.

Kavan L.,J. Heyrovsky Institute of Physical Chemistry
Chemical Record | Year: 2012

Selected problems of electrochemical synthesis, characterization and applications of titanium dioxide are reviewed. These issues have attracted considerable attention from addressing purely academic questions up to promising applications in devices for energy storage and energy conversion. Copyright © 2012 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

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