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    Ruthenium Nanoparticles Supported on Reduced Graphene Oxide: Efficient Catalyst for the Catalytic Reduction of Cr(VI) in the Presence of Amine-Boranes
    (Wiley-V C H Verlag Gmbh, 2020) Yurderi, Mehmet; Bulut, Ahmet; Kanberoglu, Gulsah Saydan; Kaya, Murat; Kanbur, Yasin; Zahmakiran, Mehmet
    Hexavalent chromium (Cr(VI)) is a toxic, mutagen and carcinogen contaminant exist in surface and groundwater, while its reduced form trivalent chromium (Cr(III)) is known as an essential element to normal carbohydrate, lipid and protein metabolism in nature. Addressed herein, for the first time, ruthenium nanoparticles supported on reduced graphene oxide (Ru@rGO) catalyze the reduction of aqueous Cr(VI) to Cr(III) in the presence of amine-boranes; ammonia-borane (AB; NH3BH3), methylamine-borane (MeAB; CH3NH2BH3), dimethylamine-borane (DMAB; (CH3)(2)NHBH3) as reducing agents under mild conditions (at room temperature and under air). Ru@rGO catalyst was reproducibly fabricated through a double-solvent method followed by wet-chemical reduction and characterized by using various spectroscopic and visualization techniques, which showed that the formation of well-dispersed and highly crystalline ruthenium(0) nanoparticles with a mean particle size of 2.7 +/- 0.9 nm on the surface of rGO. The catalytic performance of Ru@rGO was investigated in terms of activity and stability in the ammonia-borane assisted reduction of Cr(VI) to Cr(III), and the sum of the results gained from these catalytic tests revealed that Ru@rGO acts as both active (TOF=7.6 mol Cr2O72-/mol Ru.min) and stable (80% of its initial activity at 90% conversion at 5(th)reuse) heterogeneous catalyst in this significant catalytic transformation. This study also reports kinetic studies for Ru@rGO catalyzed Cr(VI) reduction in the presence of ammonia-borane depending on ruthenium ([Ru]), ammonia-borane ([AB]) concentrations and temperature to shed some light on the nature of the catalytic reaction and activation parameters.
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    ZIF-8 decorated FeMo nanoparticles: H2 Production from the catalytic hydrolysis of ammonia-borane
    (Wiley, 2024) Yilmaz, Can; Yildirim, Huseyin Ali; Top, Tuba; Yurderi, Mehmet; Zahmakiran, Mehmet
    Ammonia-Borane (AB) is considered a promising solid hydrogen storage material due to its high hydrogen content (19.6 wt%) and its use for safe hydrogen transport. The most effective way to produce H-2 from AB is to perform the hydrolysis reaction in the presence of a suitable catalyst. In this study, Fe0.2Mo0.8/ZIF-8 nanocatalyst was synthesized in two steps: (i) synthesis by following the colloidal synthesis technique by thermal decomposition of Mo(CO)(6) and Fe(acac)(3) in the presence of OM and ODE at high temperatures, and (ii) the resulting colloidal Fe0.2Mo0.8 NPs were decorated into ZIF-8. The as-prepared Fe0.2Mo0.8/ZIF-8 catalyst was identified using advanced characterization techniques such as ICP-OES, P-XRD, SEM, SEM-EDX, TEM, TEM-EDX, XPS, and BET. The catalytic activities of the Fe0.2Mo0.8/ZIF-8 catalyst in the hydrolysis of AB were investigated in different parameters (temperature, catalyst [Fe0.2Mo0.8] and substrate [H3NBH3] concentration, and recyclability). The results show that high crystallinity Fe0.2Mo0.8 NPs with a uniform 1.31 +/- 0.13 nm distribution were formed on the ZIF-8 surface. Fe0.2Mo0.8/ZIF-8 catalyst provides a maximum H-2 generation rate of 184.2 mLH(2) (g catalyst)(-1) (min)(-1) at 343 K. This uniquely cost-effective, active and durable Fe0.2Mo0.8/ZIF-8 catalyst has strong potential for H-2-based fuel cell (PEM: Proton Exchange Membrane) applications where AB is a suitable H-2 carrier.