Search

Your search keyword '"Kónya, Zoltán"' showing total 555 results
Start Over Author "Kónya, Zoltán" Search Limiters Full Text
555 results on '"Kónya, Zoltán"'

2. CO2 Conversion on N-Doped Carbon Catalysts via Thermo- and Electrocatalysis: Role of C-NO x Moieties.

Author

Hursán, Dorottya, Ábel, Marietta, Baán, Kornélia, Fako, Edvin, Samu, Gergely, Nguyën, Huu, López, Núria, Kónya, Zoltán, Sápi, András, Janáky, Csaba, and Atanassov, Plamen

Abstract

N-doped carbon (N-C) materials are increasingly popular in different electrochemical and catalytic applications. Due to the structural and stoichiometric diversity of these materials, however, the role of different functional moieties is still controversial. We have synthesized a set of N-C catalysts, with identical morphologies (∼27 nm pore size). By systematically changing the precursors, we have varied the amount and chemical nature of N-functions on the catalyst surface. The CO2 reduction (CO2R) properties of these catalysts were tested in both electrochemical (EC) and thermal catalytic (TC) experiments (i.e., CO2 + H2 reaction). CO was the major CO2R product in all cases, while CH4 appeared as a minor product. Importantly, the CO2R activity changed with the chemical composition, and the activity trend was similar in the EC and TC scenarios. The activity was correlated with the amount of different N-functions, and a correlation was found for the -NO x species. Interestingly, the amount of this species decreased radically during EC CO2R, which was coupled with the performance decrease. The observations were rationalized by the adsorption/desorption properties of the samples, while theoretical insights indicated a similarity between the EC and TC paths.

Published
2022

9. Three-dimensional Printing of Complex Graphite Structures

Author

Sajadi, Seyed Mohammad, Enayat, Shayan, Vásárhelyi, Lívia, Alabastri, Alessandro, Lou, Minghe, Sassi, Lucas M., Kutana, Alex, Bhowmick, Sanjit, Durante, Christian, Kukovecz, Ákos, Puthirath, Anand B., Kónya, Zoltán, Vajtai, Robert, Boul, Peter, Tiwary, Chandra Shekhar, Rahman, Muhammad M., and Ajayan, Pulickel M.

Subjects
Condensed Matter - Materials Science
Abstract

Graphite, with many industrial applications, is one of the widely sought-after allotropes of carbon. The sp2 hybridized and thermodynamically stable form of carbon forms a layered structure with strong in-plane carbon bonds and weak inter-layer van der Waals bonding. Graphite is also a high-temperature ceramic, and shaping them into complex geometries is challenging, given its limited sintering behavior even at high temperatures. Although the geometric design of the graphite structure in many of the applications could dictate its precision performance, conventional synthesis methods for formulating complex geometric graphite shapes are limited due to the intrinsic brittleness and difficulties of high-temperature processing. Here, we report the development of colloidal graphite ink from commercial graphite powders with reproducible rheological behavior that allows the fabrication of any complex architectures with tunable geometry and directionality via 3D printing at room temperature. The method is enabled via using small amounts of clay, another layered material, as an additive, allowing the proper design of the graphene ink and subsequent binding of graphite platelets during printing. Sheared layers of clay are easily able to flow, adapt, and interface with graphite layers forming strong binding between the layers and between particles that make the larger structures. The direct ink printing of complex 3D architectures of graphite without further heat treatments could lead to easy shape engineering and related applications of graphite at various length scales, including complex graphite molds or crucibles. The 3D printed complex graphitic structures exhibit excellent thermal, electrical, and mechanical properties, and the clay additive does not seem to alter these properties due to the excellent inter-layer dispersion and mixing within the graphite material., Comment: 19 pages, 4 figures

Published
2020

29. Mechanochemical and wet chemical syntheses of CaIn-layered double hydroxide and its performance in a transesterification reaction compared to those of other Ca2M(III) hydrocalumites (M: Al, Sc, V, Cr, Fe, Ga) and Mg(II)-, Ni(II)-, Co(II)- or Zn(II)-based hydrotalcites

Author

Szabados, Márton, Adél Ádám, Anna, Traj, Péter, Muráth, Szabolcs, Baán, Kornélia, Bélteky, Péter, Kónya, Zoltán, Kukovecz, Ákos, Sipos, Pál, and Pálinkó, István

Published
2020
Full Text
View/download PDF

30. Design of Bismuth Tungstate Bi 2 WO 6 Photocatalyst for Enhanced and Environmentally Friendly Organic Pollutant Degradation.

Author

El Aouni, Aicha, El Ouardi, Mohamed, Arab, Madjid, Saadi, Mohamed, Haspel, Henrik, Kónya, Zoltán, Ben Ali, Abdelkader, Jada, Amane, BaQais, Amal, and Ait Ahsaine, Hassan

Subjects
TUNGSTEN trioxide, POLLUTANTS, X-ray photoelectron spectroscopy, BISMUTH, PHOTOELECTRON spectroscopy, OPTICAL spectroscopy
Abstract

In this study, a chemical precipitation approach was adopted to produce a photocatalyst based on bismuth tungstate Bi2WO6 for enhanced and environmentally friendly organic pollutant degradation. Various tools such as X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), optical spectroscopy and X-ray photoelectron spectroscopy, were employed to assess the structural and morphological properties. Hence, the XRD profiles showed a well crystallized Bi2WO6 orthorhombic phase. The photocatalytic performance of the resulting photocatalyst was assessed by the decomposition of Rhodamine B (RhB) and methyl orange (MO) with a decomposition efficiency of 97 and 92%, along with the highest chemical oxygen demand of 82 and 79% during 120 min of illumination, respectively. The principal novelty of the present work is to focus on the changes in the crystalline structure, the morphology, and the optical and the photoelectrochemical characteristics of the Bi2WO6, by tuning the annealing temperature of the designed photocatalyst. Such physicochemical property changes in the as-prepared photocatalyst will affect in turn its photocatalytic activity toward the organic pollutant decomposition. The photocatalytic mechanism was elaborated based on electrochemical impedance spectroscopy, photocurrent analysis, photoluminescence spectroscopy, and radical trapping measurements. The overall data indicate that the superoxide O2•− and holes h+ are the principal species responsible for the pollutant photodegradation. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

39. Compact USB measurement and analysis system for real-time fluctuation enhanced sensing

Author

Mingesz, Robert, Gingl, Zoltan, Kukovecz, Akos, Konya, Zoltan, Kordas, Krisztian, and Moilanen, Hannu

Subjects
Physics - Instrumentation and Detectors, Physics - Chemical Physics, Physics - Data Analysis, Statistics and Probability
Abstract

Measuring the resistance fluctuations of gas sensors provides new opportunities to enhance the selectivity and sensitivity of the sensor. Taking advantage of this possibility requires special low-noise measurement hardware and software to acquire data and perform analysis. In this paper we will present a small, USB-powered device capable of doing precise measurement of the resistance fluctuations of different kinds of gas sensors. We have developed a graphical user interface software to control the parameters of the measurement, to collect data and perform real time analysis on the measured data. The analysis is based on a PCA algorithm, which is proven to be a high performance tool to support fluctuation enhanced sensing. The system has been tested on Taguchi and carbon nanotube based gas sensors as well. The main advantages of the system include the small form factor, low cost and the fully featured software performing all required data analysis operations. Complemented with a gas sensor and an optional test chamber, the setup can serve as an efficient tool for practical fluctuation-enhanced gas sensing., Comment: ICNF2011 conference

Published
2011
Full Text
View/download PDF

42. Lacunarity as a quantitative measure of mixing—a micro-CT analysis-based case study on granular materials.

Author

Vásárhelyi, Lívia, Sebők, Dániel, Szenti, Imre, Tóth, Ádám, Lévay, Sára, Vajtai, Róbert, Kónya, Zoltán, and Kukovecz, Ákos

Subjects
MATERIALS science, GRANULAR materials, COMPUTED tomography, QUALITATIVE chemical analysis, ENVIRONMENTAL impact analysis
Abstract

In practically every industry, mixing is a fundamental process, yet its 3D analysis is scarce in the literature. High-resolution computed tomography (micro-CT) is the perfect X-ray imaging tool to investigate the mixing of granular materials. Other than qualitative analysis, 3D micro-CT images provide an opportunity for quantitative analysis, which is of utmost importance, in terms of efficiency (time and budget) and environmental impact of the mixing process. In this work, lacunarity is proposed as a measure of mixing. By the lacunarity calculation on the repeated micro-CT measurements, a temporal description of the mixing can be given in three dimensions. As opposed to traditional mixing indices, the lacunarity curve provides additional information regarding the spatial distribution of the grains. Discrete element method simulations were also performed and showed similar results to the experiments. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

49. Semi-Synthetic Dihydrotestosterone Derivatives Modulate Inherent Multidrug Resistance and Sensitize Colon Cancer Cells to Chemotherapy

Author

Nagy, Ferenc István, primary, Adamecz, Dóra Izabella, additional, Baji, Ádám, additional, Kiricsi, Ágnes, additional, Huliák, Ildikó, additional, Rónavári, Andrea, additional, Kónya, Zoltán, additional, Frank, Éva, additional, Gopisetty, Mohana Krishna, additional, and Kiricsi, Mónika, additional

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results