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204 results on '"Bouša, Daniel"'

1. Solution-processed GaSe nanoflake-based films for photoelectrochemical water splitting and photoelectrochemical-type photodetectors

Author

Zappia, Marilena Isabella, Bianca, Gabriele, Bellani, Sebastiano, Serri, Michele, Najafi, Leyla, Oropesa-Nuñez, Reinier, Martín-García, Beatriz, Bouša, Daniel, Sedmidubský, David, Pellegrini, Vittorio, Sofer, Zdeněk, Cupolillo, Anna, and Bonaccorso, Francesco

Subjects
Physics - Applied Physics, Condensed Matter - Materials Science
Abstract

Gallium selenide (GaSe) is a layered compound, which has been exploited in nonlinear optical applications and photodetectors due to its anisotropic structure and pseudo-direct optical gap. Theoretical studies predicted that its two-dimensional (2D) form is a potential photocatalyst for water splitting reactions. Herein, we first report the photoelectrochemical (PEC) characterization of GaSe nanoflakes (single-/few-layer flakes), produced via liquid phase exfoliation, for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both acidic and alkaline media. In 0.5 M H2SO4, the GaSe photoelectrodes display the best PEC performance, i.e. a ratiometric power-saved metric for HER ({\Phi}saved,HER) of 0.09% and a ratiometric power-saved metric for OER ({\Phi}saved,OER) of 0.25%. When used as PEC-type photodetectors, GaSe photoelectrodes show a responsivity of ~0.16 A W-1 upon 455 nm illumination at light intensity of 63.5 uW cm-2 and applied potential of -0.3 V vs. reversible hydrogen electrode (RHE). The stability analysis of the GaSe photodetectors evidences a durable operation over tens of cathodic linear sweep voltammetry scans in 0.5 M H2SO4 for HER. Viceversa, degradation effects have been observed in both alkaline and anodic operation due to highly oxidizing environment and O2-induced (photo-)oxidation effects. Our results provide new insight into PEC properties of GaSe nanoflakes for their exploitation in photoelectrocatalysis, PEC-type photodetectors and (bio)sensors.

Published
2020
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15. Comparison of GO and polymer microcapacitors prepared by ion beam writing

Author

Malinský, Petr, primary, Romanenko, Oleksandr, additional, Havránek, Vladimir, additional, Hnatowicz, Vladimir, additional, Stammers, James Henry, additional, Cutroneo, Mariapompea, additional, Novák, Josef, additional, Slepička, Petr, additional, Svorčík, Václav, additional, Szőkölová, Kateřina, additional, Bouša, Daniel, additional, Sofer, Zdeněk, additional, and Macková, Anna, additional

Published
2020
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17. Flexible freestanding MoS₂-based composite paper for energy conversion and storage

Author

Zoller, Florian, Luxa, Jan, Bein, Thomas, Fattakhova-Rohlfing, Dina, Bouša, Daniel, and Sofer, Zdeněk

Subjects
Maschinenbau
Abstract

The construction of flexible electrochemical devices for energy storage and generation is of utmost importance in modern society. In this article, we report on the synthesis of flexible MoS2-based composite paper by high-energy shear force milling and simple vacuum filtration. This composite material combines high flexibility, mechanical strength and good chemical stability. Chronopotentiometric charge–discharge measurements were used to determine the capacitance of our paper material. The highest capacitance achieved was 33 mF·cm−2 at a current density of 1 mA·cm−2, demonstrating potential application in supercapacitors. We further used the material as a cathode for the hydrogen evolution reaction (HER) with an onset potential of approximately −0.2 V vs RHE. The onset potential was even lower (approximately −0.1 V vs RHE) after treatment with n-butyllithium, suggesting the introduction of new active sites. Finally, a potential use in lithium ion batteries (LIB) was examined. Our material can be used directly without any binder, additive carbon or copper current collector and delivers specific capacity of 740 mA·h·g−1 at a current density of 0.1 A·g−1. After 40 cycles at this current density the material still reached a capacity retention of 91%. Our findings show that this composite material could find application in electrochemical energy storage and generation devices where high flexibility and mechanical strength are desired. https://www.beilstein-journals.org/bjnano/articles/10/147

Published
2019

18. Solution‐Processed GaSe Nanoflake‐Based Films for Photoelectrochemical Water Splitting and Photoelectrochemical‐Type Photodetectors

Author

Zappia, Marilena Isabella, primary, Bianca, Gabriele, additional, Bellani, Sebastiano, additional, Serri, Michele, additional, Najafi, Leyla, additional, Oropesa‐Nuñez, Reinier, additional, Martín‐García, Beatriz, additional, Bouša, Daniel, additional, Sedmidubský, David, additional, Pellegrini, Vittorio, additional, Sofer, Zdeněk, additional, Cupolillo, Anna, additional, and Bonaccorso, Francesco, additional

Published
2020
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30. Air-stable superparamagnetic metal nanoparticles entrapped in graphene oxide matrix

Author

Tuček, Jiří, Sofer, Zdeněk, Bouša, Daniel, Pumera, Martin, Holá, Kateřina, Malá, Aneta, Poláková, Kateřina, Havrdová, Markéta, Čépe, Klára, Tomanec, Ondřej, and Zbořil, Radek

Subjects
Article
Abstract

Superparamagnetism is a phenomenon caused by quantum effects in magnetic nanomaterials. Zero-valent metals with diameters below 5 nm have been suggested as superior alternatives to superparamagnetic metal oxides, having greater superspin magnitudes and lower levels of magnetic disorder. However, synthesis of such nanometals has been hindered by their chemical instability. Here we present a method for preparing air-stable superparamagnetic iron nanoparticles trapped between thermally reduced graphene oxide nanosheets and exhibiting ring-like or core-shell morphologies depending on iron concentration. Importantly, these hybrids show superparamagnetism at room temperature and retain it even at 5 K. The corrected saturation magnetization of 185 Am2 kg–1 is among the highest values reported for iron-based superparamagnets. The synthetic concept is generalized exploiting functional groups of graphene oxide to stabilize and entrap cobalt, nickel and gold nanoparticles, potentially opening doors for targeted delivery, magnetic separation and imaging applications., Zero-valent metallic nanoparticles can exhibit superparamagnetism, due to quantum effects in magnetic nanomaterials, but their syntheses can be hindered by chemical instability. Here, the authors prepare air-stable superparamagnetic nanoparticles trapped between thermally reduced graphene oxide nanosheets.

Published
2016

44. Chemical Composition, Thermal Analysis and Pozzolanic Activity of Biomass Ash from Miscanthus.

Author

Jankovský, Ondřej, Lauermannová, Anna-Marie, Bouša, Daniel, Bartůněk, Vilém, Záleská, Martina, Pavlíková, Milena, and Pavlík, Zbyšek

Subjects
BIOMASS, ASH (Combustion product), MISCANTHUS, POZZOLANIC reaction, THERMAL analysis, ALUMINUM silicates
Abstract

In this contribution, we would like to show that biomass ash coming from combustion of Miscanthus Giganteus can be used for fabrication of blended cement-based composites due to its high pozzolanic activity and suitable chemical nature. Biomass ash composition was characterized using X-ray fluorescence and energy dispersive spectroscopy. The phase composition was analyzed in detail by X-ray diffraction. Moreover, the thermal stability was analyzed using simultaneous thermal analysis. In the next step, the pozzolanic activity was analyzed using modified Chapelle test. Potentiometric method was used for pH measurement. Since the biomass ash was pozzolana active, it is potentially suitable as a pozzolana active admixture in cement, lime and alkali activated aluminosilicate composites. [ABSTRACT FROM AUTHOR]

Published
2018
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47. Graphene oxide layers modified by light energetic ions

Author

Malinský, Petr, primary, Macková, Anna, additional, Mikšová, Romana, additional, Kováčiková, Helena, additional, Cutroneo, Mariapompea, additional, Luxa, Jan, additional, Bouša, Daniel, additional, Štrochová, Beata, additional, and Sofer, Zdeněk, additional

Published
2017
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50. Graphane Nanostripes

Author

Wang, Lu, primary, Sofer, Zdeněk, additional, Bouša, Daniel, additional, Sedmidubský, David, additional, Huber, Štěpán, additional, Matějková, Stanislava, additional, Michalcová, Alena, additional, and Pumera, Martin, additional

Published
2016
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