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    Wyświetlanie 1-4 z 4
    Tytuł:
    TiO2 nanotubes : synthesis and application
    Nanorurki TiO2 : synteza i zastosowanie
    Autorzy:
    Mazierski, Paweł
    Powiązania:
    https://bibliotekanauki.pl/articles/2057910.pdf
    Data publikacji:
    2021
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    nanorurki TiO2
    materiały jednowymiarowe
    fotokataliza heterogeniczna
    TiO2 nanotubes
    one-dimensional materials
    heterogeneous photocatalysis
    Opis:
    Among all transition-metal oxides, TiO2 is one of the most studied compounds in materials science. Its tested in many applications such as biomedical, photochemical, electrical and environmental. Among these applications, maximization of the surface area to achieve the highest efficiency is crucial, thus nanostructured forms of TiO2 are very popular. TiO2 can be obtained in the form of zero-dimensional materials (nanoparticles), one-dimensional (nanowires, nanotubes), two-dimensional (nanosheets) and three-dimensional (nanospheres). Among these various nanostructured forms of TiO2, nanotubes are of the greatest interest due to high electron mobility, quantum confinement effects, a high specific surface area and very high mechanical strength. One-dimensional TiO2 nanotubes can be synthesized using the template, hydro/solvothermal, electrospinning and anodic oxidation methods, which leads to obtaining material in the form of a powder or a thin layer. Notwithstanding, ordered layers of TiO2 nanotubes obtained by anodic oxidation are particularly interesting in terms of application. This mini-review provides an overview of preparation methods of TiO2 nanotubes as well describes its most important applications with attention to key features.
    Źródło:
    Wiadomości Chemiczne; 2021, 75, 11-12; 1195--1209
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Kataliza procesów hydrosililowania z udziałem cieczy jonowych
    Catalysis of hydrosilylation processes with the participation of ionic liquids
    Autorzy:
    Bartlewicz, Olga
    Szymańska, Anna
    Jankowska-Wajda, Magdalena
    Dąbek, Izabela
    Maciejewski, Hieronim
    Powiązania:
    https://bibliotekanauki.pl/articles/1413312.pdf
    Data publikacji:
    2021
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    hydrosililowanie
    kompleksy Rh
    kompleksy Pt
    ciecze jonowe
    SILPC
    kataliza heterogeniczna
    hydrosilylation
    Rh complexes
    Pt complexes
    ionic liquids
    heterogeneous catalysis
    Opis:
    Hydrosilylation is a fundamental and elegant method for the laboratory and industrial synthesis of organosilicon compounds. The hydrosilylation reaction is usually performed in a single-phase homogeneous system. A major problem, particularly in homogeneous catalysis, is the separation of catalyst from the reaction mixture. The presence of metals in the reaction products, even in trace quantities, is unacceptable for many applications, therefore efforts have been made at applying heterogeneous catalysts or immobilised metal complexes in order to obtain high catalytic activity and easy product isolation at the same time. One of the methods for producing such catalysts is the employment of ionic liquids as agents for the immobilization of metal complexes. Biphasic catalysis in a liquid-liquid system is an ideal approach through which to combine the advantages of both homogeneous and heterogeneous catalysis. The ionic liquids (ILs) generally form the phase in which the catalyst is dissolved and immobilized. In our research we have obtained a number of catalytic systems of such a type which were based on rhodium and platinum complexes dissolved in phosphonium, imidazolium, pyridinium and ammonium liquids. Currently, there has a common trend to obtain heterogenized systems that combine advantages of homogeneous and heterogeneous catalysis, which makes the hydrosilylation process more cost- effective. Such integration of homo- and heterogeneous catalysts is realized in several variants, as supported IL phase catalysts (SILPC) and solid catalysts with ILs layer (SCILL). Although all the above systems show high catalytic activities, their structure is unknown. This is why we have made attempts to modify selected ionic liquids (corresponding to our most effective systems) and we have applied them as ligands in the synthesis of platinum and rhodium complexes. Another group of catalysts comprises anionic complexes of rhodium and platinum which were obtained by reactions between halide complexes of metals and a respective ionic liquid. Most of the obtained complexes are solids insoluble in hydrosilylation reagents and are characterized by a high catalytic activity. A considerable development of heterogeneous catalysts of this type and their application in many hydrosilylation processes can be expected in the future. This mini-review briefly describes the recent progress in the design and development of catalysts based on the presence of ionic liquids and their applications for hydrosilylation processes.
    Źródło:
    Wiadomości Chemiczne; 2021, 75, 1-2; 5-29
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Functional materials based on carbon : encapsulated iron nanoparticles
    Materiały funkcjonalne oparte na magnetycznych nanokapsułkach węglowych
    Autorzy:
    Kasprzak, Artur
    Popławska, Magdalena
    Koszytkowska-Stawińska, Mariola
    Powiązania:
    https://bibliotekanauki.pl/articles/2057908.pdf
    Data publikacji:
    2021
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    nanomateriały węglowe
    magnetyczne nanokapsułki węglowe
    nanomedycyna
    elektrochemia
    kataliza heterogeniczna
    adsorpcja
    carbon nanomaterials
    carbon-encapsulated iron nanoparticles
    nanomedicine
    electrochemistry
    heterogeneous catalysis
    adsorption
    Opis:
    The chemistry of carbon nanomaterials attracts continuous attention of scientists because of their promising properties and applications. Carbon-encapsulated iron nanoparticles (CEINs) are subgroup of carbon nanomaterials. CEINs are the core-shell nanostructures including the metallic phase permanently encapsulated in a tight carbon coating. The carbon shell protects CEINs against oxidation of metal into a corresponding oxide, as well as prevents them from spontaneous aggregation. It has been documented that the magnetic properties of CEINs are superior in comparison with the respective materials comprising metal oxides. Additionally, the presence of the carbon shell enables surface functionalization of CEINs by means of various synthetic routes, both covalent and non-covalent ones. Chemical functionalization enables tuning the materials’ properties and applications, for example toward introducing catalytically active sites or improving colloidal stability. One may conclude that CEINs combine physicochemical properties of graphene and iron nanoparticle. Therefore, this is prospective material for many applications. In this article, we discuss the properties, chemistry and selected applications of CEINs.
    Źródło:
    Wiadomości Chemiczne; 2021, 75, 11-12; 1211--1233
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Gold catalysts supported on zeolites
    Katalizatory złotowe osadzone na zeolitach
    Autorzy:
    Walkowiak, Adrian
    Powiązania:
    https://bibliotekanauki.pl/articles/2057912.pdf
    Data publikacji:
    2021
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    heterogeniczne katalizatory złotowe
    nanocząstki złota
    zeolity
    metody modyfikacji zeolitów złotem
    zastosowanie zeolitów modyfikowanych złotem
    proces katalityczny
    heterogeneous gold catalysts
    gold nanoparticles
    zeolites
    methods of zeolites modification with gold
    application of gold-modified zeolites
    catalytic process
    Opis:
    Heterogeneous gold catalysis is a relatively young but dynamically developing field of chemistry. At the end of the 1980s, Masatake Haruta and Graham Hutchings provided experimental evidence of high activity of supported gold catalysts in CO oxidation and acetylene hydrochlorination. Thus, these two researchers challenged the prevailing chemists’ belief that gold is almost completely chemically inert and catalytically inactive. Since then, gold catalysis has been constantly in the centre of attention of a wide array of scientists from around the world. However, there are still many questions about the nature of catalysts containing this noble metal, which inspires in-depth research in this field. From among various potential supports for gold heterogeneous catalysts, zeolites have drawn much attention thanks to several unique properties of this group of materials, among which the most important are high thermal stability and the presence of a system of pores of strictly defined sizes. Zeolites have extremely large surface area, which is desirable to obtain high dispersion of the active phase. The article provides a concise overview of the methods of gold nanoparticles deposition on zeolitic supports and catalytic applications of such materials. The first chapter sheds light on the properties of bulk and nano-sized Au and depicts the background of gold catalysis development. In the following part, a brief description of zeolites and their properties is delivered. The third chapter is devoted entirely to the description of several preparation methods of zeolite-supported gold catalysts and their applications in different catalytic processes. The following post-synthetic methods of zeolite modification with gold are described: impregnation, ion exchange, deposition-reduction, chemical vapour deposition, and grafting. The most important advantages and disadvantages of each method are summarized. The article concludes with a résumé of literature reports concerning the use of zeolitesupported gold catalysts in various processes. Special attention was paid to selective oxidation of alcohols and biomass-derived chemicals (e.g. glucose).
    Źródło:
    Wiadomości Chemiczne; 2021, 75, 11-12; 1259--1293
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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