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Article Citation - WoS: 125Citation - Scopus: 133Supported Copper-Copper Oxide Nanoparticles as Active, Stable and Low-Cost Catalyst in the Methanolysis of Ammonia-Borane for Chemical Hydrogen Storage(Elsevier Science Bv, 2015) Yurderi, Mehmet; Bulut, Ahmet; Ertas, Ilknur Efecan; Zahmakiran, Mehmet; Kaya, MuratThe physical mixture of copper (Cu) copper(I) oxide (Cu2O) and copper(II) oxide (CuO) nanoparticles supported on activated carbon (Cu-Cu2O-CuO/C) were reproducibly prepared by a simple deposition-reduction technique without using any stabilizer in water at room temperature. The characterization of the resulting material by ICP-OES, P-XRD, XPS, DR-UV/vis, BFTEM and HRTEM techniques reveals that the formation of well-dispersed highly crystalline 3.8 +/- 1.7 nm nanoparticles on the surface of activated carbon. These carbon supported Cu-Cu2O-CuO nanoparticles were employed as heterogeneous catalyst in the methanolysis of ammonia-borane (NH3BH3), which has been considered as one of the attractive materials for the efficient storage of hydrogen, under mild conditions. We found that only 3.0 mol % Cu-Cu2O-CuO/C catalyst is enough to catalyze the methanolysis of ammonia-borane with high activity (TOF = 24 min(-1)) and conversion (>99%) at room temperature. More importantly, the exceptional stability of supported Cu-Cu2O-CuO nanoparticles against to sintering and leaching make Cu-Cu2O-CuO/C recyclable catalyst for the methanolysis of ammonia-borane. Cu-Cu2O-CuO/C catalyst retains >76% of its initial activity with 94% of conversion even at 8th recycle in the methanolysis of ammonia-borane at complete conversion. The study reported here also includes the collection of kinetic data for Cu-Cu2O-CuO/C catalyzed methanolysis of ammonia-borane depending on catalyst [Cu], substrate [NH3BH3] concentrations and temperature to determine the rate expression and the activation parameters (E-a, Delta H-#, and Delta S-#) of the catalytic reaction. (C) 2014 Published by Elsevier B.V.Article Citation - WoS: 141Citation - Scopus: 147Carbon Dispersed Copper-Cobalt Alloy Nanoparticles: a Cost-Effective Heterogeneous Catalyst With Exceptional Performance in the Hydrolytic Dehydrogenation of Ammonia-Borane(Elsevier, 2016) Bulut, Ahmet; Yurderi, Mehmet; Ertas, Ilknur Efecan; Celebi, Metin; Kaya, Murat; Zahmakiran, MehmetHerein, we report the development of a new and cost-effective nanocatalyst for the hydrolytic dehydrogenation of ammonia-borane (NH3BH3), which is considered to be one of the most promising solid hydrogen carriers due to its high gravimetric hydrogen storage capacity (19.6 wt%) and low molecular weight. The new catalyst system consisting of bimetallic copper-cobalt alloy nanoparticles supported on activated carbon was simply and reproducibly prepared by surfactant-free deposition-reduction technique at room temperature. The characterization of this new catalytic material was done by the combination of multi-pronged techniques including ICP-MS, XRD, XPS, BFTEM, HR-TEM, STEM and HAADF-STEM-line analysis. The sum of their results revealed that the formation of copper-cobalt alloy nanoparticles (d(mean) =1.8 nm) on the surface of activated carbon (CuCo/C). These new carbon supported copper-cobalt alloy nanoparticles act as highly active catalyst in the hydrolytic dehydrogenation of ammonia-borane, providing an initial turnover frequency of TOF = 2700 h(-1) at 298 K, 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, easy recovery and high durability of these supported CuCo nanoparticles make CuCo/C recyclable heterogeneous catalyst for the hydrolytic dehydrogenation of ammonia-borane. They retain almost their inherent activity even at 10th catalytic reuse in the hydrolytic dehydrogenation of ammonia-borane at 298K. (C) 2015 Elsevier B.V. All rights reserved.
