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Kayaalp, Bu&gcaron,ra,Lee, Siwon,Klauke, Kurt,Seo, Jongsu,Nodari, Luca,Kornowski, Andreas,Jung, WooChul,Mascotto, Simone Elsevier 2019 Applied Catalysis B Vol.245 No.-
<P> The design of perovskite oxides with improved textural properties in combination with tunable composition variations is a forward-looking strategy for the preparation of next generation catalytic converter. In the present work we report the template-free synthesis of mesoporous solid solutions of La<SUB>0.3</SUB>Sr<SUB>0.7</SUB>Ti<SUB>1-x</SUB>Fe<SUB>x</SUB>O<SUB>3±δ</SUB> (0≤x≤0.5) and the study of their catalytic performance towards CH<SUB>4</SUB> and CO oxidation. Using an innovative polymer complex route, phase pure perovskite solid solutions with specific surface area of 65m<SUP>2</SUP> g<SUP>-1</SUP> and average pore size of 15 nm were prepared. The iron concentration increase led to a progressive enhancement of not only both concentration and transport of the charge carriers but also reducibility and oxygen desorption capability on the catalyst. As a result, we observed almost complete conversion of CH<SUB>4</SUB> and CO at 600 ℃ and 300 ℃, respectively. Kinetic studies on methane oxidation showed that competing <I>suprafacial</I> and <I>intrafacial</I> reaction mechanisms coexist, and that the concentration of 30% of Fe maximizes the <I>suprafacial</I> contribution. Under reducing conditions at 600 ℃ the materials retained their structural and morphological integrity, showing superior stability. Finally, the reaction rate of CH<SUB>4</SUB> and CO conversion evidenced that our systems are by a maximum of 90 times more performing than other bulk and nanoporous Fe-based perovskites in literature (e.g. La<SUB>0.66</SUB>Sr<SUB>0.34</SUB>Co<SUB>0.2</SUB>Fe<SUB>0.8</SUB>O<SUB>3-δ</SUB>), as a result their large surface area, intimate gas-solid contact and short intragrain oxygen diffusion pathways induced by the mesoporous structure. </P>
Ko, Seungpil,Na, Junhong,Moon, Young-Sun,Zschieschang, Ute,Acharya, Rachana,Klauk, Hagen,Kim, Gyu-Tae,Burghard, Marko,Kern, Klaus American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.49
<P>Ultrathin sheets of two-dimensional (2D) materials like transition metal dichalcogenides have attracted strong attention as components of high-performance light-harvesting devices. Here, we report the implementation of Schottky junction-based photovoltaic devices through site-selective surface doping of few-layer WSe2 in lateral contact configuration. Specifically, whereas the drain region is covered by a strong molecular p-type dopant (NDP-9) to achieve an Ohmic contact, the source region is coated with an Al2O3 layer, which causes local n-type doping and correspondingly an increase of the Schottky barrier at the contact. By scanning photocurrent microscopy using green laser light, it could be confirmed that photocurent generation is restricted to the region around the source contact. The local photoinduced charge separation is associated with a photoresponsivity of up to 20 mA W-1 and an external quantum efficiency of up to 1.3%. The demonstrated device concept should be easily transferrable to other van der Waals 2D materials.</P>