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Article Citation - WoS: 102Citation - Scopus: 107Copper(0) Nanoparticles Supported on Silica-Coated Cobalt Ferrite Magnetic Particles: Cost Effective Catalyst in the Hydrolysis of Ammonia-Borane With an Exceptional Reusability Performance(Amer Chemical Soc, 2012) Kaya, Murat; Zahmakiran, Mehmet; Ozkar, Saim; Volkan, MurvetHerein we report the development of a new and cost-effective nanocomposite catalyst for the hydrolysis of ammonia-borane (NH3BH3), which is considered to be one of the most promising solid hydrogen carriers because of its high gravimetric hydrogen storage capacity (19.6% wt) and low molecular weight. The new catalyst system consisting of copper nanoparticles supported on magnetic SiO2/CoFe2O4 particles was reproducibly prepared by wet-impregnation of Cu(II) ions on SiO2/CoFe2O4 followed by in situ reduction of the Cu(II) ions on the surface of magnetic support during the hydrolysis of NH3BH3 and characterized by ICP-MS, XRD, XPS, TEM, HR-TEM and N-2 adsorption-desorption technique. Copper nanoparticles supported on silica coated cobalt(II) ferrite SiO2/CoFe2O4 (CuNPs@SCF) act as highly active catalyst in the hydrolysis of ammonia-borane, providing an initial turnover frequency of TOF = 2400 h(-1) at room temperature, which is not only higher than all the non-noble metal catalysts but also higher than the majority of the noble metal based homogeneous and heterogeneous catalysts employed in the same reaction.. More importantly, they were easily recovered by using a permanent magnet in the reactor wall and reused for up, to 10 recycles without losing their inherent catalytic activity significantly, which demonstrates the exceptional reusability of the CuNPs@SCF catalyst.Article Citation - WoS: 86Nanoceria-Supported Ruthenium(0) Nanoparticles: Highly Active and Stable Catalysts for Hydrogen Evolution From Water(Amer Chemical Soc, 2018) Demir, Elif; Akbayrak, Serdar; Onal, Ahmet M.; Ozkar, SaimRuthenium(0) nanoparticles supported on nanoceria (Ru-0/CeO2) were prepared by reduction of Ru3+ ions on the surface of ceria using aqueous solution of NaBH4. The Ru-0/CeO2 samples were characterized by advanced analytical tools and employed as electrocatalysts on the glassy carbon electrode (GCE) in hydrogen evolution from water. The GCE, modified by Ru-0/CeO2 (1.86 wt % Ru), provides an incredible electrocatalytic activity with a high exchange current density of 0.67 mA.cm(-2), low overpotential of 47 mV at j = 10 mA.cm(-2), and small Tafel slope of 41 mV.dec(-1). Moreover, this modified GCE provides an unprecedented long-term stability without changing the onset potential (33 mV) even after 10 000 scans in acidic water splitting at room temperature. The hydrogen gas, evolved during the water splitting using the Ru-0/CeO2 (1.86 wt % Ru) electrocatalyst, was also collected. The amount of the evolved H-2 gas matches well with the calculated value, which indicates the achievement of nearly 100% Faradaic efficiency.
