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Article Citation - WoS: 13Citation - Scopus: 13Ruthenium 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, MehmetHexavalent 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.Article Citation - WoS: 41Citation - Scopus: 45Palladium Nanoparticles Decorated Graphene Oxide: Active and Reusable Nanocatalyst for the Catalytic Reduction of Hexavalent Chromium(vi)(Wiley-v C H verlag Gmbh, 2017) Celebi, Metin; Karakas, Kadir; Ertas, Ilknur Efecan; Kaya, Murat; Zahmakiran, MehmetToday, the catalytic reduction of Cr(VI) to Cr(III) stands one of the most important challenges in the environmental chemistry and catalysis due to highly stable, contaminant and toxic nature of Cr(VI). In this study, we show that a new nanocatalyst system comprised of 3-aminopropyltriethoxysilane (APTS) stabilized palladium(0) nanoparticles grafted onto the surface of graphene oxide (Pd/GO) efficiently works in the catalytic reduction of Cr(VI) to Cr(III) under mild reaction conditions. Pd/GO nanocatalyst was reproducibly prepared through two-steps procedure: (i) H-2 reduction of Pd(dba)2(dba= dibenzylideneacetone) in the presence of APTS in THF to synthesize colloidal APTS stabilized palladium(0) nanoparticles and then (ii) the deposition of 3-aminopropyltriethoxysilane stabilized palladium 0) nanoparticles onto the surface of graphene oxide (GO) by impregnation. The characterization of Pd/GO was carried out by advanced analytical techniques. The summation of the results acquired from these analyses reveals that the formation of well-dispersed and highly crystalline palladium(0) nanoparticles on the surface of GO. The catalytic performance of the resulting Pd/GO in terms of activity and stability was assessed in the catalytic reduction of Cr(VI) to Cr(III) in aqueous solution in the presence of formic acid (HCOOH) as a reducing agent. We found that Pd/GO nanocatalyst exhibits high activity (TOF= 3.6 mol Cr2O72-/mol Pdxmin) and reusability (> 90% at 5th reuse) in this catalytic transformation at room temperature.
