Feyyaz Durap

Dihydrogen Phosphate Stabilized Ruthenium(0) Nanoparticles: Efficient Nanocatalyst for The Hydrolysis of Ammonia-Borane at Room Temperature

Intensive efforts have been devoted to the development of new materials for safe and efficient hydrogen storage. Among them, ammonia-borane appears to be a promising candidate due to its high gravimetric hydrogen storage capacity. Ammonia-borane can release hydrogen on hydrolysis in aqueous solution under mild conditions in the presence of a suitable catalyst. Herein, we report the synthesis of ruthenium(0) nanoparticles stabilized by dihydrogenphosphate anions with an average particle size of 2.9 ± 0.9 nm acting as a water-dispersible nanocatalyst in the hydrolysis of ammonia-borane. They provide an initial turnover frequency (TOF) value of 80 min−1 in hydrogen generation from the hydrolysis of ammonia-borane at room temperature. Moreover, the high stability of these ruthenium(0) nanoparticles makes them long-lived and reusable nanocatalysts for the hydrolysis of ammonia-borane. They provide 56,800 total turnovers and retain ~80% of their initial activity even at the fifth catalytic run in the hydrolysis of ammonia-borane at room temperature.

Chiral phosphinites as efficient ligands for enantioselective Ru(II), Rh(I) and Ir(III)-catalyzed transfer hydrogenation reactions

Metal-catalyzed enantioselective transfer reduction of ketones to enantiomerically enriched chiral alcohols has recently attracted attention. Therefore, a series of methyl alkyl or alkyl/aryl ketones have been reduced by using Ru(II), Rh(I) and Ir(III) catalysts based on C2-symmetric chiral ferrocenyl phosphinite ligands. The corresponding optically active secondary alcohols were obtained in excellent conversions and moderate-to-good enantioselectivities. The best results were obtained with an iridium catalyst, giving up to 98% conversion and 80% ee.

Amine-functionalized graphene nanosheet-supported PdAuNi alloy nanoparticles: efficient nanocatalyst for formic acid dehydrogenation

Formic acid (HCOOH), a major by-product of biomass processing with high energy density, stability and non-toxicity, has a great potential as a safe and a convenient liquid hydrogen (H2) storage material for combustion engines and fuel cell applications. However, high-purity hydrogen release from the catalytic decomposition of aqueous formic acid solution at desirable rates under mild conditions stands as a major challenge that needs to be solved for the practical use of formic acid in on-demand hydrogen generation systems. Described herein is a new nanocatalyst system comprised of 3-aminopropyltriethoxysilane-functionalized graphene nanosheet-supported PdAuNi alloy nanoparticles (PdAuNi/f-GNS), which can reproducibly be prepared by following double solvent method combined with liquid-phase chemical reduction, all at room temperature. PdAuNi/f-GNS selectively catalyzes the decomposition of aqueous formic acid through the dehydrogenation pathway (∼100% H2 selectivity), in the absence of any promoting additives (alkali formates, Bronsted bases, Lewis bases, etc.). PdAuNi/f-GNS nanocatalyst provides CO-free H2 generation with a turnover frequency of 1090 mol H2 mol metal−1 h−1 in the additive-free dehydrogenation of formic acid at almost complete conversion (≥92%) even at room temperature. The catalytic activity provided by PdAuNi/f-GNS nanocatalyst is higher than those obtained with the heterogeneous catalysts reported to date for the additive-free dehydrogenation of formic acid. Moreover, PdAuNi/f-GNS nanoparticles show high durability against sintering, clumping and leaching throughout the catalytic runs, so that the PdAuNi/f-GNS nanocatalyst retains almost its inherent catalytic activity and selectivity at the end of the 10th recycle.

p(HEMA)-Pd(II) and p(HEMA-MAH)-Pd(II) Microspheres: Efficient, Recyclable and Ligand-Free Catalyst for Suzuki-Miyaura Cross-Coupling Reaction in Water

In this study, the authors report the synthesis and characterization of new poly(hydroxyethyl methacrylate) palladium(II) (p(HEMA)-Pd(II)) and poly(hydroxyethyl methacrylate-N-methacryloyl-(L)-histidine methyl ester) palladium(II), p(HEMA-MAH)-Pd(II) microsphere catalysts, and their catalysis in Suzuki-Miyaura coupling reactions of aryl bromides with phenylboronic acid in water. The microsphere catalysts were characterized by SEM, ICP-MS, FTIR, and diffuse-reflactance UV-visible spectroscopy. The p(HEMA)-Pd(II) and p(HEMA-MAH)-Pd(II) microsphere catalysts were active catalysts in Suzuki-Miyaura coupling reactions of arylbromides with phenylboronic acid affording biphenyls in high yield. Recycling experiments showed that the p(HEMA)-Pd(II) and p(HEMA-MAH)-Pd(II) microsphere catalysts could be used seven or ten times with essentially no loss in activity in the Suzuki-Miyaura coupling reactions.

Influence of temperature and light intensity on Ru(II) complex based organic-inorganic device

An organic-inorganic junction was fabricated by forming [Ru(Cy2PNHCH2-C4H3O)(η6-p-cymene)Cl2] complex thin film using spin coating technique on n-Si and evaporating Au metal on the film. It was seen that the structure had perfect rectification property. Current-voltage (I-V) measurements were carried out in dark and under various illumination conditions (between 50-100 mW/cm2) and with the temperature range from 303 to 380 K. The structure showed unusually forward and reverse bias temperature and light sensing behaviors. It was seen that the current both in forward and reverse bias increased with the increase in light intensity and temperature.