Browsing by Subject "Iridium"

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    ItemOpen Access
    Influence of La and Si promoters on the anaerobic heterogeneous catalytic decomposition of ammonium dinitramide (ADN) via alumina supported iridium active sites
    (Elsevier, 2022-02-25) Kurt, Merve; Kap, Zeynep; Senol, Sinem; Ercan, Kerem Emre; Sika-Nartey, Abel Tetteh; Kocak, Yusuf; Koc, A.; Esiyok, H.; Caglayan, B. S.; Aksoylu, A. E.; Ozensoy, Emrah
    Structural origins of the promotional effects of the La or Si doping of alumina supported Ir catalysts in anaerobic ammonium dinitramide decomposition were investigated. Our findings reveal that Ir/Al2O3 and Ir/La-Al2O3 favorably lower the onset temperature of the ADN decomposition reaction, whereas Si doping boosts the pressure generation during the reaction. Formation of mostly metallic Ir nanoparticles for Ir/Al2O3 and Ir/La-Al2O3 enables the lowering of the activation energy of the reaction. On the other hand, enhancement due to Si promotion is associated to the generation of small oxidic Irnx+ clusters which are strongly interacting with the SiOx-AlOx surface domains of the support material. Fundamental structure-functionality relationships unraveled in the current work may allow design of novel catalytic systems for aerospace monopropellant propulsion systems with higher performance by simultaneous exploitation of Ir active sites with different electronic properties.
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    ItemOpen Access
    On the structural and electronic properties of Ir-silicide nanowires on Si(001) surface
    (American Institute of Physics Inc., 2016) Fatima; Oguz I. C.; Çakır, D.; Hossain, S.; Mohottige, R.; Gulseren, O.; Oncel, N.
    Iridium (Ir) modified Silicon (Si) (001) surface is studied with Scanning Tunneling Microscopy/Spectroscopy (STM/STS) and Density Functional Theory (DFT). A model for Ir-silicide nanowires based on STM images and ab-initio calculations is proposed. According to our model, the Ir adatom is on the top of the substrate dimer row and directly binds to the dimer atoms. I-V curves measured at 77 K shows that the nanowires are metallic. DFT calculations confirm strong metallic nature of the nanowires.