TY - JOUR AU - Ayyubov, Ilgar AU - Berghian-Grosan, C. AU - Dodony, Erzsébet AU - Pászti, Zoltán AU - Borbáth, Irina AU - Szegedi, Ágnes AU - Vulcu, A. AU - Tompos, András AU - Tálas, Emília TI - Structure–Catalytic Behavior Relationships in TiO2-Carbon Composite Supported Pt Electrocatalysts: A Case Study JF - ANALYTICAL LETTERS J2 - ANAL LETT VL - in press PY - 2024 SP - in press PG - 21 SN - 0003-2719 DO - 10.1080/00032719.2024.2351589 UR - https://m2.mtmt.hu/api/publication/34873019 ID - 34873019 AB - Composite types of supports made of TiO2 and carbonaceous materials provide higher stability for the Pt electrocatalysts under the working conditions of polymer electrolyte membrane fuel cells than the traditional carbon supports. We have demonstrated in our previous work that composites with general formula of 75 wt.% Ti(1-x)MoxO2-25 wt.% C (x = 0–0.2; C = traditional Black Pearls (BP) carbon) were promising supports which provided increased stability for the Pt electrocatalysts. In this study, the effect of nitrogen doping of the carbonaceous component of the composite was explored. 75 wt.% TiO2-25 wt.% carbon composite supports were prepared using graphite oxide (GO), N-doped GO and N-doped multilayer graphene. Electrocatalysts were made by loading the supports with 20 wt.% Pt. The systems were compared based on their physicochemical properties determined by low-temperature nitrogen adsorption, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and conductivity measurements. The activity of the catalysts was investigated by conventional methods in a 3-electrode electrochemical cell. The results of various characterization methods contributed to the understanding of the difference in the electrochemical properties of N-free and N-containing catalyst samples. While GO was favorable for this composite supported catalyst, its N-doping strongly influenced the growth of TiO2, forming an almost continuous coating of small TiO2 crystals. This quasi-insulating TiO2 layer between the Pt catalytic sites and the conductive part of the composite resulted in poor electrochemical activity. Mixing the sample with carbon improved its conductivity, which resulted in a significant increase in the oxygen reduction activity. © 2024 Taylor & Francis Group, LLC. LA - English DB - MTMT ER - TY - CHAP AU - Dodony, Erzsébet AU - Radnóczi, György Zoltán AU - Dódony, István ED - Fried, Miklós TI - TEM study of copper silicides T2 - Symposium on Materials Science 2023 PB - Óbudai Egyetem CY - Budapest SN - 9789634493532 PY - 2024 SP - 31 EP - 32 PG - 2 UR - https://m2.mtmt.hu/api/publication/34880187 ID - 34880187 LA - English DB - MTMT ER - TY - JOUR AU - Dodony, Erzsébet AU - Dódony, István AU - Sáfrán, György TI - EDIC intensity correction of electron diffraction JF - MICRON J2 - MICRON VL - 183 PY - 2024 PG - 6 SN - 0968-4328 DO - 10.1016/j.micron.2024.103649 UR - https://m2.mtmt.hu/api/publication/34852839 ID - 34852839 AB - Transmission electron microscopy (TEM) has recently become indispensable in determining crystal structures. The location of atoms in crystals can be determined using electron diffraction (ED) intensity data series if the diffracted intensities are directly proportional to the square of the structure factor (|Fhkl|2). However, due to the crystal thickness, the used electron wavelength and the potential misalignment of the measured crystal the detected intensities differ from the ideal values. A method, Electron Diffraction Intensity Correction (EDIC), and a computer program have been developed to recover the ideal |Fhkl|2 proportional intensities from experimental data for kinematic scattering, for further structure studies. LA - English DB - MTMT ER - TY - JOUR AU - Fogarassy, Zsolt AU - Wójcicka, Aleksandra AU - Cora, Ildikó AU - Rácz, Adél Sarolta AU - Grzanka, Szymon AU - Dodony, Erzsébet AU - Perlin, Piotr AU - Borysiewicz, Michał A. TI - Structural and electrical investigation of Al/Ti/TiN/Au based N-face n-GaN contact stack JF - MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING J2 - MAT SCI SEMICON PROC VL - 175 PY - 2024 PG - 12 SN - 1369-8001 DO - 10.1016/j.mssp.2024.108250 UR - https://m2.mtmt.hu/api/publication/34714097 ID - 34714097 AB - In this work, the structure of Ti/Al/TiN/Au contact layer stack on the N-face of a single-crystal n-GaN substrate is studied after heat treatment at 750 °C. Since TiN is widely regarded as a diffusion barrier in the stack, the formed structures with three different initial TiN thicknesses (15, 60 and 90 nm) in the contact layers are investigated in detail. The primary tool used for the structural investigations was a (scanning) transmission electron microscope ((S)TEM). In all three samples a low resistivity ohmic contact was formed. However, the TiN layer has not completely blocked the diffusion for any of the samples and both Al and Au diffused through the TiN layer at the temperature of 750 °C. As a result of the heat treatment, a complex AlN/TiN/Au2Al/TiN/Au + Al2.67O4 stack was formed on the surface of the GaN substrate. The measurements have not shown the often reported Ti–Al alloy phase in the samples. The formation of the AlN and TiN layers can be explained by the separation of N from GaN creating N vacancies in the GaN substrate which could help the formation of the ohmic behavior. LA - English DB - MTMT ER - TY - JOUR AU - Cadena Nogales, Ana Cristina AU - Pekker, Áron AU - Botka, Bea AU - Dodony, Erzsébet AU - Fogarassy, Zsolt AU - Pécz, Béla AU - Kamarás, Katalin TI - Encapsulation of the Graphene Nanoribbon Precursor 1, 2, 4‐trichlorobenzene in Boron Nitride Nanotubes at Room Temperature JF - PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS J2 - PHYS STATUS SOLIDI-R VL - 17 PY - 2023 IS - 1 PG - 5 SN - 1862-6254 DO - 10.1002/pssr.202200284 UR - https://m2.mtmt.hu/api/publication/33138741 ID - 33138741 LA - English DB - MTMT ER - TY - CONF AU - Dodony, Erzsébet AU - Dódony, István AU - Sáfrán, György ED - Fried, Miklós TI - In-situ study of nickel silicide formation in thin films T2 - Symposium on Materials Science 2022 PB - Óbudai Egyetem C1 - Budapest SN - 9789634493204 PY - 2023 SP - 32 EP - 33 PG - 5 UR - https://m2.mtmt.hu/api/publication/33751712 ID - 33751712 LA - English DB - MTMT ER - TY - CONF AU - Dodony, Erzsébet AU - Dódony, István AU - Fogarassy, Zsolt AU - Pekker, Péter AU - Sáfrán, György ED - Steinbach, Gábor TI - DIFFRAKCIÓS INTENZITÁS MÉRÉSEK TEM-BEN II.: AZ EWALD KORREKCIÓ KITERJESZTÉSE. Diffracted intensity measurements in TEM II.: Extension of the Ewald correction TS - Diffracted intensity measurements in TEM II.: Extension of the Ewald correction T2 - A Magyar Mikroszkópos Társaság éves konferenciájának kivonatkönyve 2023 : Book of the Abstracts of the Annual Conference of HSM 2023 PY - 2023 SP - 28 EP - 31 PG - 4 UR - https://m2.mtmt.hu/api/publication/34487420 ID - 34487420 N1 - Előadás LA - English DB - MTMT ER - TY - CONF AU - Dodony, Erzsébet AU - Dódony, István AU - Fogarassy, Zsolt AU - Pekker, Péter AU - Sáfrán, György ED - Steinbach, Gábor TI - A γ -NIKKEL-SZILICID SZERKEZETI VÁLTOZATOSSÁGA. Structural variability of the γ-nickel-silicide TS - Structural variability of the γ-nickel-silicide T2 - A Magyar Mikroszkópos Társaság éves konferenciájának kivonatkönyve 2023 : Book of the Abstracts of the Annual Conference of HSM 2023 PY - 2023 SP - 26 EP - 28 PG - 3 UR - https://m2.mtmt.hu/api/publication/34487369 ID - 34487369 N1 - Előadás LA - English DB - MTMT ER - TY - JOUR AU - Maria Cristina, Silva Cisneros AU - Salmanzade, Khirdakhanim AU - Borbáth, Irina AU - Dodony, Erzsébet AU - Olasz, Dániel AU - Sáfrán, György AU - Kuncser, Andrei AU - Pásztiné Gere, Erzsébet AU - Tompos, András AU - Pászti, Zoltán TI - Reductive Treatment of Pt Supported on Ti0.8Sn0.2O2-C Composite: A Route for Modulating the Sn–Pt Interactions JF - NANOMATERIALS J2 - NANOMATERIALS-BASEL VL - 13 PY - 2023 IS - 15 PG - 23 SN - 2079-4991 DO - 10.3390/nano13152245 UR - https://m2.mtmt.hu/api/publication/34088284 ID - 34088284 AB - The composites of transition metal-doped titania and carbon have emerged as promising supports for Pt electrocatalysts in PEM fuel cells. In these multifunctional supports, the oxide component stabilizes the Pt particles, while the dopant provides a co-catalytic function. Among other elements, Sn is a valuable additive. Stong metal-support interaction (SMSI), i.e., the migration of a partially reduced oxide species from the support to the surface of Pt during reductive treatment is a general feature of TiO2-supported Pt catalysts. In order to explore the influence of SMSI on the stability and performance of Pt/Ti0.8Sn0.2O2-C catalysts, the structural and catalytic properties of the as prepared samples measured using XRD, TEM, XPS and electrochemical investigations were compared to those obtained from catalysts reduced in hydrogen at elevated temperatures. According to the observations, the uniform oxide coverage of the carbon backbone facilitated the formation of Pt–oxide–C triple junctions at a high density. The electrocatalytic behavior of the as prepared catalysts was determined by the atomic closeness of Sn to Pt, while even a low temperature reductive treatment resulted in Sn–Pt alloying. The segregation of tin oxide on the surface of the alloy particles, a characteristic material transport process in Sn–Pt alloys after oxygen exposure, contributed to a better stability of the reduced catalysts. LA - English DB - MTMT ER - TY - JOUR AU - Varga, Gábor AU - Szenti, Imre AU - Kiss, János AU - Baán, Kornélia AU - Halasi, Gyula AU - Óvári, László AU - Szamosvölgyi, Ákos AU - Mucsi, Róbert AU - Dodony, Erzsébet AU - Fogarassy, Zsolt AU - Pécz, Béla AU - Olivi, Luca AU - Sápi, András AU - Kukovecz, Ákos AU - Kónya, Zoltán TI - Decisive role of Cu/Co interfaces in copper cobaltite derivatives for high performance CO2 methanation catalyst JF - JOURNAL OF CO2 UTILIZATION J2 - J CO2 UTIL VL - 75 PY - 2023 PG - 13 SN - 2212-9820 DO - 10.1016/j.jcou.2023.102582 UR - https://m2.mtmt.hu/api/publication/34120023 ID - 34120023 AB - Thermo-catalytic bio-SNG (CH4) production is one of the useful tools for converting waste to gaseous fuels through CO2 conversion. To abundant properly, however, efficient, robust and cost-effective catalysts would be required. Bimetallic systems based on transition metals seem to be promising candidates for this task. The CoCu bimetallic system with in-situ generated interfaces was synthesized and used as a catalyst for CO2 methanation. The in-depth analysis of the structure-activity-selectivity relationships involving XRD, (NAP-)XPS, EXAFS and TEM-EDX revealed that the co-existence of Co0, CoO, and Cu0 in the proper distribution on the surface can ensure the selective production of methane. To fine-tune the surface composition of the bimetallic systems, a systematic alteration of the Cu:Co ratio in the precursor spinel structures must be performed. Cu0.4Co2.6O4 derivative, stabilizing subsurface Cu(I)–O specimen, showed the best performance with high activity (12,800 nmol g–1 s–1) and a remarkable selectivity of 65–85% for methane in a wide temperature range (250–425 °C). In studying the mechanistic aspects of methanation, it has been shown that the hydrogenation of active carbon at the surface or below the surface is the key step for the production of methane. So far, this cobalt-catalyzed sub-step has been proposed in catalytic Fischer-Tropsch syntheses. LA - English DB - MTMT ER -