Przeglądaj wg Autor "Cmielewska, Katarzyna"

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  • Miniatura
    PozycjaOpen Access
    CO2 Reduction to Valuable Chemicals on TiO2-Carbon Photocatalysts Deposited on Silica Cloth
    (MDPI, 2021-12-28) Morawski, Antoni W.; Cmielewska, Katarzyna; Witkowski, Kordian; Kusiak-Nejman, Ewelina; Pelech, Iwona; Staciwa, Piotr; Ekiert, Ewa; Sibera, Daniel; Wanag, Agnieszka; Gano, Marcin; Narkiewicz, Urszula; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie
    A new photocatalyst for CO2 reduction has been presented. The photocatalyst was prepared from a combination of a commercial P25 with a mesopore structure and carbon spheres with a microporous structure with high CO2 adsorption capacity. Then, the obtained hybrid TiO2-carbon sphere photocatalysts were deposited on a glass fiber fabric. The combined TiO2-carbon spheres/silica cloth photocatalysts showed higher efficiency in the two-electron CO2 reduction towards CO than in the eight-electron reaction to methane. The 0.5 g graphitic carbon spheres combined with 1 g of TiO2 P25 resulted in almost 100% selectivity to CO. From a practical point of view, this is promising as it economically eliminates the need to separate CO from the gas mixture after the reaction, which also contains CH4 and H-2.
  • Miniatura
    PozycjaOpen Access
    New Insight on Carbon Dioxide-Mediated Hydrogen Production
    (Chemistry Europe, European Chemical Societies Publishing, 2022-04-03) Morawski, Antoni W.; Kusiak-Nejman, Ewelina; Pełech, Iwona; Cmielewska, Katarzyna; Sibera, Daniel; Staciwa, Piotr; Wanag, Agnieszka; Gano, Marcin; Ekiert, Ewa; Kapica-Kozar, Joanna; Witkowski, Kordian; Narkiewicz, Urszula; Zachodniopomorski Uniwersytet Technologiczny w Szczecinie
    A new approach to hydrogen production from water is described. This simple method is based on carbon dioxide-mediated water decomposition under UV radiation. The water contained dissolved sodium hydroxide, and the solution was saturated with gaseous carbon dioxide. During saturation, the pH decreased from about 11.5 to 7-8. The formed bicarbonate and carbonate ions acted as scavengers for hydroxyl radicals, preventing the recombination of hydroxyl and hydrogen radicals and prioritizing hydrogen gas formation. In the presented method, not yet reported in the literature, hydrogen production is combined with carbon dioxide. For the best system with alkaline water (0.2 m NaOH) saturated with CO2 under UV-C, the hydrogen production amounted to 0.6 mu mol h(-1) during 24 h of radiation.