Izzet Amour Morkan

Bio: Izzet Amour Morkan is an academic researcher from Abant Izzet Baysal University. The author has contributed to research in topics: Catalysis & Dehydrogenation. The author has an hindex of 6, co-authored 14 publications receiving 182 citations.

Rhodium(0) nanoparticles supported on nanotitania as highly active catalyst in hydrogen generation from the hydrolysis of ammonia borane

Abstract: Rhodium(0) nanoparticles supported on the surface of titanium dioxide (Rh(0)@TiO2) were in situ generated from the reduction of rhodium(III) ions impregnated on nanotitania during the hydrolysis of ammonia borane. They were isolated from the reaction solution by centrifugation and characterized by a combination of advanced analytical techniques. The results show that (i) highly dispersed rhodium(0) nanoparticles with sizes in the range 1.3–3.8 nm were formed on the surface of titanium dioxide, (ii) Rh(0)@TiO2 shows high catalytic activity in hydrogen generation from the hydrolysis of ammonia borane with a turnover frequency value up to 260 min−1 at 25.0 ± 0.1 °C, (iii) the results of kinetic studies on the hydrogen generation from the hydrolysis of ammonia borane were also reported including the activation energy of 65.5 ± 2 kJ mol−1 for this reaction.

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

Abstract: Driven by functionality and purity demand for applications of inorganic nanoparticle colloids in optics, biology, and energy, their surface chemistry has become a topic of intensive research interest. Consequently, ligand-free colloids are ideal reference materials for evaluating the effects of surface adsorbates from the initial state for application-oriented nanointegration purposes. After two decades of development, laser synthesis and processing of colloids (LSPC) has emerged as a convenient and scalable technique for the synthesis of ligand-free nanomaterials in sealed environments. In addition to the high-purity surface of LSPC-generated nanoparticles, other strengths of LSPC include its high throughput, convenience for preparing alloys or series of doped nanomaterials, and its continuous operation mode, suitable for downstream processing. Unscreened surface charge of LSPC-synthesized colloids is the key to achieving colloidal stability and high affinity to biomolecules as well as support materials,...

Dehydrogenation of Ammonia Borane by Metal Nanoparticle Catalysts

Abstract: Ammonia borane (AB), having a high hydrogen density of 19.6 wt %, has attracted much attention as a promising chemical hydrogen storage material. In the past few years, a number of highly active metal nanoparticle (NP) catalysts, which are easy to handle and separate, have been developed for AB dehydrogenation. In this Perspective, we summarize new progress in the development of metal NP catalysts, which are categorized into monometallic and heterometallic catalysts, with excellent activity and high recyclability for different AB dehydrogenation pathways, including solvolysis (hydrolysis and methanolysis) in protic solvents and dehydrocoupling in nonprotic solvents, and we survey the corresponding methods for the regeneration of AB. Moreover, the merits and drawbacks of solvolysis and dehydrocoupling are discussed.

Ru and Ru–Ni Nanoparticles on TiO2 Support as Extremely Active Catalysts for Hydrogen Production from Ammonia–Borane

Abstract: Highly dispersed monometallic Ru nanoparticles can be successfully synthesized on TiO2 supports for effective hydrogen production from ammonia–borane (NH3·BH3; AB). The choice of support material and reduction methods were confirmed to significantly influence the size of the Ru nanoparticles, and smaller sizes of Ru nanoparticles with a mean diameter of 1.7 nm could be formed on a TiO2 support material by H2 reduction at 200 °C. The catalytic activity of the Ru nanoparticles can be significantly enhanced by alloying with Ni atoms, whereby a significantly high total turnover number (TTO) of approximately 153000 over 8 h was achieved with an excellent turnover frequency (TOF) of 914 min–1 and an activation energy of 28.1 kJ mol–1. Detailed characterization by means of TEM, EDX, H2-TPR, and in situ XAFS measurements revealed that a synergistic alloying effect originates from the random distribution of Ru–Ni nanoparticles with a mean diameter of 2.3 nm and plays a crucial role in the exceptional catalytic per...

Ceria supported rhodium nanoparticles: Superb catalytic activity in hydrogen generation from the hydrolysis of ammonia borane

Abstract: We investigated the effect of various oxide supports on the catalytic activity of rhodium nanoparticles in hydrogen generation from the hydrolysis of ammonia borane. Among the oxide supports (CeO2, SiO2, Al2O3, TiO2, ZrO2, HfO2) ceria provides the highest catalytic activity for the rhodium(0) nanoparticles in the hydrolysis of ammonia borane. Rhodium(0) nanoparticles supported on nanoceria (Rh0/CeO2) were prepared by the impregnation of rhodium(III) ions on the surface of ceria followed by their reduction with sodium borohydride in aqueous solution at room temperature. They were isolated from the reaction solution by centrifugation and characterized by a combination of advanced analytical techniques. The catalytic activity of Rh0/CeO2 samples with various rhodium loading in the range of 0.1–4.0% wt. Rh was also tested in hydrogen generation from the hydrolysis of ammonia borane at room temperature. The highest catalytic activity was achieved by using 0.1% wt. rhodium loaded nanoceria. The resulting Rh0/CeO2 with a metal loading of 0.1% wt. Rh show superb catalytic activity in hydrogen generation from the hydrolysis of ammonia borane with a record turnover frequency value (TOF) of 2010 min−1 at 25.0 ± 0.1 °C. The superb catalytic activity of Rh0/CeO2 is ascribed to the reducible nature of ceria. The reduction of cerium(IV) to cerium(III) leads to a build-up of negative charge on the oxide surface which favors the bonding of rhodium(0) nanoparticles on the surface and, thus, their catalytic activity. Rh0/CeO2 are also reusable catalysts preserving 67% of their initial catalytic activity even after the fifth use in hydrogen generation from the hydrolysis of ammonia borane at room temperature (TOF = 1350 min−1. The work reported here also includes the kinetic studies depending on the temperature to determine the activation energy (Ea = 43 ± 2 kJ/mol) and the effect of catalyst concentration on the rate of hydrolysis of ammonia borane.