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Papers by Aydın Haşimoğlu

Research paper thumbnail of An effective synthesis route for improving the catalytic activity of carbon-supported Co–B catalyst for hydrogen generation through hydrolysis of NaBH4

International Journal of Hydrogen Energy, 2014

Abstract A novel method for synthesis of carbon-supported cobalt boride catalyst was developed fo... more Abstract A novel method for synthesis of carbon-supported cobalt boride catalyst was developed for hydrogen generation from catalytic hydrolysis of NaBH4 solution. The activated carbon and carbon black supported catalysts prepared by “reduction–precipitation” method were found to be much more active than those prepared by conventional “impregnation–reduction” method inspite of the same Co content. A maximum hydrogen generation was achieved using carbon black supported Co–B, which lowers the activation energy to 56.7 kJ mol−1. The effects of NaOH concentration (1–15 wt.%), NaBH4 concentration (5–20 wt.%) and reaction temperature (25–40 °C) on the performance of the most active catalyst (Co–B/CB) were investigated in detail. The results indicated that this catalyst can be used in a hydrogen generator for mobile applications such as PEMFC systems due to its high catalytic activity and simple preparation method.

Research paper thumbnail of The development of catalytic performance by coating Pt–Ni on CMI7000 membrane as a cathode of a microbial fuel cell

Bioresource Technology, 2015

Performance of cathode materials in microbial fuel cell (MFC) from dairy wastewater has been inve... more Performance of cathode materials in microbial fuel cell (MFC) from dairy wastewater has been investigated in laboratory tests. Both cyclic voltammogram experiments and MFC tests showed that Pt-Ni cathode much better than pure Pt cathode. MFC with platinum cathode had the maximum power density of 0.180 W m(-2) while MFC with Pt:Ni (1:1) cathode produced the maximum power density of 0.637 W m(-2), even if the mass mixing ratio of Pt is lower in the alloy were used. The highest chemical oxygen demand (COD) removal efficiency was around 82-86% in both systems. The cyclic voltammogram (CV) analyses show that Pt:Ni (1:1) offers higher specific surface area than Pt alone does. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) results showed that entire Pt:Ni (1:1) alloys can reduce the oxygen easily than pure platinum, even though less precious metal amount. The main outcome of this study is that Pt-Ni, may serve as a alternative catalyst in MFC applications.

Research paper thumbnail of Kinetic properties of co-reduced Co-B/graphene catalyst powder for hydrogen generation of sodium borohydride

Journal of Renewable and Sustainable Energy, 2015

The aim of the present work is to investigate the kinetic properties of Co-B nanoparticles which ... more The aim of the present work is to investigate the kinetic properties of Co-B nanoparticles which are deposited on graphene sheets by simultaneous chemical reduction of Co+2 and graphite oxides using NaBH4 as the reducing agent. The reduced Co−B/graphene nanocomposites were characterized by X-ray diffraction, and the effects of the concentration of NaBH4, NaOH, and hydrolytic temperature were discussed in detail. The results show that the concentration of NaBH4 and NaOH indeed exerted a significant impact on the hydrogen generation rate of Co-B/graphene catalysts. Reaction rate of hydrolysis first rises up and then decreases subsequently with the rising of NaOH and NaBH4 concentration. The results show that the Co-B/graphene catalyst has the high catalytic activity with activation energy of 52.45 kJ·mol−1, and showed high resistance against deterioration and stability as a function of time. The present method is promising for the synthesis of effective supported catalysts for hydroly...

Research paper thumbnail of Synthesis of graphene-based Co-B catalyst via simultaneous chemical reduction for hydrolysis of sodium borohydride

Journal of Renewable and Sustainable Energy, 2013

Co-B nanoparticles are deposited on graphene sheets by simultaneous chemical reduction of Co+2 an... more Co-B nanoparticles are deposited on graphene sheets by simultaneous chemical reduction of Co+2 and graphite oxides using NaBH4 as the reducing agent. The reduced Co−B/graphene nanocomposites were characterized by X-ray diffraction, Fourier transform infrared spectra, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The results show that after reduction, not only considerable amount of functional groups has been removed but also exhibited formation of Co-B alloy on the graphene sheets. The catalytic activity of nanocomposites was investigated by the hydrolysis of NaBH4 in aqueous solution. Graphene support material greatly enhances the hydrolysis of NaBH4 with respect to graphite and active carbon supports, and chemical reduced graphene sheets can readily form stable aqueous colloids through electrostatic stabilization. The present method is promising for the synthesis of effective supported catalysts for hydrolysis of NaBH4.

Research paper thumbnail of Low loaded Pt-Co catalyst surfaces optimized by magnetron sputtering sequential deposition technique for PEM fuel cell applications: Physical and electrochemical analysis on carbon paper support

TURKISH JOURNAL OF CHEMISTRY, 2021

Research paper thumbnail of Fast and effective methylene blue adsorption onto graphene oxide/amberlite nanocomposite: Evaluation and comparison of optimization techniques

Korean Journal of Chemical Engineering

Research paper thumbnail of Naproxen Adsorption onto Graphene Oxide Nanopowders: Equilibrium, Kinetic, and Thermodynamic Studies

Water, Air, & Soil Pollution

Research paper thumbnail of Synthesis, characterization and an application of graphene oxide nanopowder: methylene blue adsorption and comparison between experimental data and literature data

Journal of Dispersion Science and Technology

Research paper thumbnail of Highly efficient recovery of biophenols onto graphene oxide nanosheets: Valorisation of a biomass

Journal of Molecular Liquids

Research paper thumbnail of An effective synthesis route for improving the catalytic activity of carbon-supported Co–B catalyst for hydrogen generation through hydrolysis of NaBH4

International Journal of Hydrogen Energy, 2014

Abstract A novel method for synthesis of carbon-supported cobalt boride catalyst was developed fo... more Abstract A novel method for synthesis of carbon-supported cobalt boride catalyst was developed for hydrogen generation from catalytic hydrolysis of NaBH4 solution. The activated carbon and carbon black supported catalysts prepared by “reduction–precipitation” method were found to be much more active than those prepared by conventional “impregnation–reduction” method inspite of the same Co content. A maximum hydrogen generation was achieved using carbon black supported Co–B, which lowers the activation energy to 56.7 kJ mol−1. The effects of NaOH concentration (1–15 wt.%), NaBH4 concentration (5–20 wt.%) and reaction temperature (25–40 °C) on the performance of the most active catalyst (Co–B/CB) were investigated in detail. The results indicated that this catalyst can be used in a hydrogen generator for mobile applications such as PEMFC systems due to its high catalytic activity and simple preparation method.

Research paper thumbnail of The development of catalytic performance by coating Pt–Ni on CMI7000 membrane as a cathode of a microbial fuel cell

Bioresource Technology, 2015

Performance of cathode materials in microbial fuel cell (MFC) from dairy wastewater has been inve... more Performance of cathode materials in microbial fuel cell (MFC) from dairy wastewater has been investigated in laboratory tests. Both cyclic voltammogram experiments and MFC tests showed that Pt-Ni cathode much better than pure Pt cathode. MFC with platinum cathode had the maximum power density of 0.180 W m(-2) while MFC with Pt:Ni (1:1) cathode produced the maximum power density of 0.637 W m(-2), even if the mass mixing ratio of Pt is lower in the alloy were used. The highest chemical oxygen demand (COD) removal efficiency was around 82-86% in both systems. The cyclic voltammogram (CV) analyses show that Pt:Ni (1:1) offers higher specific surface area than Pt alone does. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) results showed that entire Pt:Ni (1:1) alloys can reduce the oxygen easily than pure platinum, even though less precious metal amount. The main outcome of this study is that Pt-Ni, may serve as a alternative catalyst in MFC applications.

Research paper thumbnail of Kinetic properties of co-reduced Co-B/graphene catalyst powder for hydrogen generation of sodium borohydride

Journal of Renewable and Sustainable Energy, 2015

The aim of the present work is to investigate the kinetic properties of Co-B nanoparticles which ... more The aim of the present work is to investigate the kinetic properties of Co-B nanoparticles which are deposited on graphene sheets by simultaneous chemical reduction of Co+2 and graphite oxides using NaBH4 as the reducing agent. The reduced Co−B/graphene nanocomposites were characterized by X-ray diffraction, and the effects of the concentration of NaBH4, NaOH, and hydrolytic temperature were discussed in detail. The results show that the concentration of NaBH4 and NaOH indeed exerted a significant impact on the hydrogen generation rate of Co-B/graphene catalysts. Reaction rate of hydrolysis first rises up and then decreases subsequently with the rising of NaOH and NaBH4 concentration. The results show that the Co-B/graphene catalyst has the high catalytic activity with activation energy of 52.45 kJ·mol−1, and showed high resistance against deterioration and stability as a function of time. The present method is promising for the synthesis of effective supported catalysts for hydroly...

Research paper thumbnail of Synthesis of graphene-based Co-B catalyst via simultaneous chemical reduction for hydrolysis of sodium borohydride

Journal of Renewable and Sustainable Energy, 2013

Co-B nanoparticles are deposited on graphene sheets by simultaneous chemical reduction of Co+2 an... more Co-B nanoparticles are deposited on graphene sheets by simultaneous chemical reduction of Co+2 and graphite oxides using NaBH4 as the reducing agent. The reduced Co−B/graphene nanocomposites were characterized by X-ray diffraction, Fourier transform infrared spectra, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The results show that after reduction, not only considerable amount of functional groups has been removed but also exhibited formation of Co-B alloy on the graphene sheets. The catalytic activity of nanocomposites was investigated by the hydrolysis of NaBH4 in aqueous solution. Graphene support material greatly enhances the hydrolysis of NaBH4 with respect to graphite and active carbon supports, and chemical reduced graphene sheets can readily form stable aqueous colloids through electrostatic stabilization. The present method is promising for the synthesis of effective supported catalysts for hydrolysis of NaBH4.

Research paper thumbnail of Low loaded Pt-Co catalyst surfaces optimized by magnetron sputtering sequential deposition technique for PEM fuel cell applications: Physical and electrochemical analysis on carbon paper support

TURKISH JOURNAL OF CHEMISTRY, 2021

Research paper thumbnail of Fast and effective methylene blue adsorption onto graphene oxide/amberlite nanocomposite: Evaluation and comparison of optimization techniques

Korean Journal of Chemical Engineering

Research paper thumbnail of Naproxen Adsorption onto Graphene Oxide Nanopowders: Equilibrium, Kinetic, and Thermodynamic Studies

Water, Air, & Soil Pollution

Research paper thumbnail of Synthesis, characterization and an application of graphene oxide nanopowder: methylene blue adsorption and comparison between experimental data and literature data

Journal of Dispersion Science and Technology

Research paper thumbnail of Highly efficient recovery of biophenols onto graphene oxide nanosheets: Valorisation of a biomass

Journal of Molecular Liquids