Pokročilé nízkodimenzionální nanomateriály

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    Carbon fibers decorated with TiO2 nanoparticles for photocatalytic degradation of methylene blue dye
    (Frontiers Media S.A., 2024-10-23) Chennam, Pavan Kumar; Sepúlveda Sepúlveda, Lina Marcela; Říhová, Martina; Alijani, Mahnaz; Kachlík, Martin; Zazpe Mendioroz, Raúl; Pavliňák, David; Maca, Karel; Macák, Jan
    This report demonstrates the development of carbon fibers (CFs) decorated with TiO2 nanoparticles (NPs) as an efficient photocatalyst for the photocatalytic degradation of methylene blue (MB) as a model dye. Carbon fibers were produced by carbonization of polyacrylonitrile fibers, previously produced by centrifugal spinning. Subsequently, the CFs were decorated with TiO2 NPs (CFs@TiO2) by tailored soaking protocol using aqueous TiCl4 solution with different concentrations (0.025, 0.05, 0.1, and 0.2 M). SEM analyses revealed that soaking in TiCl4 produced a smooth, conformal, continuous TiO2 nanoparticulate coating with thickness increasing from 40.4 +/- 21.2 to 257.9 +/- 63.9 nm with increasing TiCl4 concentration. X-ray diffraction and Raman spectroscopy confirmed the anatase nature of TiO2. Photocatalytic decomposition rates of MB were assessed under UV light illumination for all CFs@TiO2 samples, and it was revealed that the lowest amount of TiO2 NP on C yielded the highest rates. The synergistic interaction between CFs and TiO2 NPs with a uniform morphology and a well-crystalline anatase structure, present in an optimal amount of fiber bodies, is the key reason for the remarkable photocatalytic performance. This work shows that C fibers decorated with an optimal amount of TiO2 NPs have a great potential as an effective photocatalytic material.
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    Structural and Optical Properties of Luminescent Copper(I) Chloride Thin Films Deposited by Sequentially Pulsed Chemical Vapour Deposition
    (MDPI, 2018-10-01) Krumpolec, Richard; Homola, Tomáš; Cameron, David Campbell; Humlíček, Josef; Caha, Ondřej; Kuldová, Karla; Zazpe Mendioroz, Raúl; Přikryl, Jan; Macák, Jan
    Sequentially pulsed chemical vapour deposition was used to successfully deposit thin nanocrystalline films of copper(I) chloride using an atomic layer deposition system in order to investigate their application to UV optoelectronics. The films were deposited at 125 degrees C using [Bis(trimethylsilyl)acetylene](hexafluoroacetylacetonato)copper(I) as a Cu precursor and pyridine hydrochloride as a new Cl precursor. The films were analysed by XRD, X-ray photoelectron spectroscopy (XPS), SEM, photoluminescence, and spectroscopic reflectance. Capping layers of aluminium oxide were deposited in situ by ALD (atomic layer deposition) to avoid environmental degradation. The film adopted a polycrystalline zinc blende-structure. The main contaminants were found to be organic materials from the precursor. Photoluminescence showed the characteristic free and bound exciton emissions from CuCl and the characteristic exciton absorption peaks could also be detected by reflectance measurements.
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    Intrinsic properties of high -aspect ratio single- and double -wall anodic TiO 2 nanotube layers annealed at different temperatures
    (Elsevier, 2020-08-20) Motola, Martin; Hromádko, Luděk; Přikryl, Jan; Sopha, Hanna Ingrid; Krbal, Miloš; Macák, Jan
    TiO2 nanotube layers of different thicknesses and tube wall morphologies exploited. Single-wall nanotubes were obtained by chemical etching of double-wall ones. Photocurrents, structure, optical and electronic properties of tubes were compared.
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    Anodization of electrodeposited titanium films towards TiO2 nanotube layers
    (Elsevier, 2020-09-01) Sopha, Hanna Ingrid; Norikawa, Yutaro; Motola, Martin; Hromádko, Luděk; Rodriguez Pereira, Jhonatan; Černý, Jiří; Nohira, Toshiyuki; Yasuda, Kouji; Macák, Jan
    Ti films electrodeposited on Ni foils from molten salts were anodized towards TiO2 nanotube formation for the first time. The resulting TiO2 nanotube (TNT) layers were compared with TNT layers prepared under identical conditions on Ti foils by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) measurements, X-ray photoelectron spectroscopy (XPS), and photocurrent measurements. No significant differences were found between the TNT layers prepared on the two different substrates. Electrodeposited Ti films prepared in this way could thus be a viable option for anodization purposes.
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    Fabrication of TiO2 nanotubes on Ti spheres using bipolar electrochemistry
    (Elsevier, 2020-02-01) Sopha, Hanna Ingrid; Hromádko, Luděk; Motola, Martin; Macák, Jan
    In this work, the anodization of Ti spheres using bipolar electrochemistry is reported for the first time. TiO2 nanotubes were found over the entire surface area of the Ti spheres when a square-wave potential was employed. The TiO2 nanotubes were similar to 77 nm in inner diameter and had a thickness of similar to 2 mu m on the extremities of the Ti spheres. Due to their increased surface area, the Ti spheres covered with TiO2 nanotubes had a rate constant for the photocatalytic degradation of methylene blue which was approximately 2.15 times higher than that of non-anodized Ti spheres with a thin thermal oxide layer.