Applied Surface Science

آخرین مقالات مجله Applied Surface Science

  1. Publication date: 28 February 2020

    Source: Applied Surface Science, Volume 504

    Author(s): Sebastian Jarczewski, Marek Drozdek, Piotr Michorczyk, Carlos Cuadrado-Collados, Jesus Gandara-Loe, Joaquín Silvestre-Albero, Lidia Lityńska-Dobrzyńska, Piotr Kuśtrowski

    Abstract

    Mesoporous MgO was synthesized by the nanoreplication method using CMK-3 carbon as a hard template and magnesium nitrate as a metal oxide precursor. The produced support was modified with different amounts of ammonium metavanadate solution. Various distributions of V-containing species on the MgO surface were found by XRD, low-temperature adsorption of N2, TEM, XPS and UV–vis-DR spectroscopy. At low V loadings isolated VO4 dominated. Increasing V content resulted in clustering of VO4 species and the formation of Mg3V2O8 crystallites. As found in temperature-programmed reduction (H2-TPR), the latter phase was clearly harder in reduction by H2 compared to highly dispersed VO4 forms. The developed materials appeared to be very active catalysts of oxidative dehydrogenation of ethylbenzene (ODH). The optimal catalytic performance was observed for the sample containing 10 wt% of vanadium. The initial ethylbenzene conversion of 63.6% at selectivity to styrene of 86.9% was achieved at temperature as low as 500 °C. A notable influence of carbonaceous deposit formed during the ODH reaction on the catalytic activity was discussed, including presentation of both coexisting superficial reaction mechanisms. A reasonable regeneration procedure to recover lost activity was developed.

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  2. Publication date: 28 February 2020

    Source: Applied Surface Science, Volume 504

    Author(s): László Péter Bakos, Dániel Karajz, András Katona, Klara Hernadi, Bence Parditka, Zoltán Erdélyi, István Lukács, Zoltán Hórvölgyi, Géza Szitási, Imre Miklós Szilágyi

    Abstract

    Carbon nanospheres were used as templates for the first time to prepare titania inverse opal photonic crystal. From the spheres, opal colloid crystals were made by vertical deposition on microscope slides, and TiO2 was grown on them using atomic layer deposition (ALD). For this technique, the relatively high thermal stability and the presence of oxygen containing functional groups on the surface of the carbon spheres are beneficial. Subsequent annealing burned out the template spheres, leaving behind the inverse opal structures. The upper solid TiO2 layer was removed with argon ion sputtering. The samples were characterized with SEM, Raman spectroscopy, XRD, EDX, UV–Vis diffuse reflectance spectroscopy and their photocatalytic activity was investigated in decomposing organic dyes under UV and visible illumination. A new approach was used to test photocatalysis on the surface by utilizing UV–Vis reflectance and Raman spectroscopy in conjunction.

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