Browsing by Author "Kazici, Hilal Celik"

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3-Acrylamidopropyl Cationic Hydrogel Modified Graphite Electrode and Its Superior Sensitivity To Hydrogen Peroxide
(Taylor & Francis inc, 2019) Caglar, Aykut; Kazici, Hilal Celik; Alpaslan, Duygu; Yilmaz, Yonca; Kivrak, Hilal; Aktas, Nahit
A highly sensitive hydrogen peroxide (H2O2) sensor is fabricated by the synthesized 3-Acrylamidopropyl-trimethylammoniumchloride (p(APTMACl)) hydrogel to covered of pen- graphite (PG) electrodes. (p(APTMACl))-PG electrode is characterized using scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The electrochemical properties of these sensors are investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The CV behavior of (p(APTMACl))-PG electrode is investigated in 0.1M PBS (pH 7, 5mm diameter of mold). The developed sensor displays significantly enhanced electrocatalytic activity through the H2O2 detection. Linear response of the sensor to H2O2 were observed in the concentration range from 0 to 130 mu M (R-2 = 0.99) with a detection limit of 1.08x10(-6) M, quantification limit of 3.62x10(-6) M (S/N=3) and sensitivity of 2375 mu A/mMcm(2). In addition, interference studies reveal that (p(APTMACl))-PG electrode is not affected by ascorbic acid (AA), uric acid (UA), and dopamine which are common interfering species. The developed sensor is also successfully applied to detect H2O2 in real commercial samples. This study describes a novel strategy to sensing characteristics to hydrogen peroxide by p(APTMACl)-PG electrode.
Ceo2 Supported Multimetallic Nano Materials as an Efficient Catalyst for Hydrogen Generation From the Hydrolysis of Nabh4
(Pergamon-elsevier Science Ltd, 2020) Izgi, Mehmet Sait; Baytar, Orhan; Sahin, Omer; Kazici, Hilal Celik
Nowadays, there is still no suitable method to store large amounts of energy. Hydrogen can be stored physically in carbon nanotubes or chemically in the form of hydride. In this study, sodium borohydride (NaBH4) was used as the source of hydrogen. However, an inexpensive and useful catalyst (Co-Cr-B/CeO2) was synthesized using the NaBH4 reduction method and its property was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), x-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) measurements. The optimized Co-Cr-B/CeO2 catalyst exhibited an excellent hydrogen generation rate (9182 mLg(metal)(-1) min(-1)) and low activation energy (35.52 kJ mol(-1)). The strong catalytic performance of the Co-Cr-B/CeO2 catalyst is thought to be based on the synergistic effect between multimetallic nanoparticles and the effective charge transfer interactions between the metal and the support material. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Co-Mn Nanoparticles Supported on Epoxy-Based Polymer as Catalyst for Evolution of H2 From Ammonia Borane Semi-Methanolysis
(Springer, 2022) Kazici, Hilal Celik; Izgi, Mehmet Sait; Sahin, Omer
A high-density and low-cost hydrogen generation technology is required for hydrogen energy systems. Non-noble multimetallic Co-Mn-B nanoparticles can serve as a good catalyst because of their low cost and ability to produce hydrogen gas during the catalytic semi-methanolysis process. This work reports the synthesis, characterization, and the use of Co-Mn-B catalyst supported on Eupergit CM as a very active and reusable catalyst for the generation of hydrogen from the semi-methanolysis of ammonia borane (AB). Solid materials were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive x-ray spectroscopy (EDX), and scanning electron microscopy (SEM). Rates of hydrogen generation were used to determine the kinetics of semi-methanolysis reaction. The parameters examined, namely the percentage of NaOH, percentage of metal loading, amount of catalyst particles, and AB concentrations and temperatures, were 1-5 (wt)%, 5-10 (wt)%, 5-50 mg, 0.5-3 mmol, and 30-60 degrees C, respectively. Total turnover frequency (TOF) value, hydrogen generation rate, and activation energy (Ea) were obtained at 30 degrees C as 15,751 h(-1), 17,324 mL g(cat)(-1)min(-1) (3 mmol AB and 25 mg Co-Mn-B/Eupergit CM), and 43.936 kJ mol(-1), respectively.
Comparative of Mil101(Cr) and Nano-Mil101(cr) Electrode as an Electrochemical Hydrogen Peroxide Sensor
(Wiley-v C H verlag Gmbh, 2022) Salman, Firat; Kazici, Hilal Celik; Gulcan, Mehmet
Herein, an electrochemical sensor for the detection of H2O2 based on nafion glassy carbon electrode modified with MIL101(Cr) and nano-MIL101(Cr) are developed and its electrochemical characterizations analyzed by CV and CA. In comparison with the NGCE, MIL101/NGCE and nano-MIL101/NGCE, the nano-MIL101/NGCE showed a sharp redox peak specific to H2O2 was obtained in the phosphate-calibrated solution. nano-MIL101/NGCE exhibited good linear response in terms of the relationship between peak currents and concentrations as from 0 to 650 mu M (R-2=0.99), with a low limit of detection 3.8 mu M, high sensitivity 986 mu A mM(-1) cm(-2) and nano-MIL101/NGCE exhibited ideal repeatability, reproducibility, stability and the interference-free perception of H2O2.
A Comprehensive Study on the Synthesis, Characterization and Mathematical Modeling of Nanostructured Co-Based Catalysts Using Different Support Materials for Ab Hydrolysis
(Springer international Publishing Ag, 2021) Kazici, Hilal Celik; Izgi, Mehmet Sait; Sahin, Omer
The present work includes the synthesis of aluminum oxide (Al2O3), multi-walled carbon nanotube (MWCNT), and Eupergit CM-supported Co-based nanoparticles (Co-Fe-B and Co-Mn-B), and the investigation of their hydrolytic efficiency in H-2 generation from the catalytic hydrolysis of ammonia borane (NH3BH3). Among the supported catalysts, Co-Fe-B/Eupergit CM exhibited the highest H-2 generation rate as 4539 mLmin(-1)g(catalyst)(-1) compared to Co-Fe-B/Al2O3 and Co-Fe-B/MWCNT, which exhibited 4373 mLmin(-1)g(catalyst)(-1) and 3294 mLmin(-1)g(catalyst)(-1), respectively. When Co-Mn-B/ Eupergit CM was used instead of Co-Fe-B/ Eupergit CM, a significant increase in the highest HGR (19.422 mLmin(-1)g(catalyst)(-1)) was found. Moreover, turnover frequency (TOF) value was calculated as 318 h(-1) and 646 h(-1) for Co-Fe-B/Eupergit CM and Co-Mn-B/Eupergit CM, respectively.
Development of Nonenzymatic Benzoic Acid Detection on Pdsn/Gce Xc-72r Prepared Via Polyol Method
(Wiley-v C H verlag Gmbh, 2019) Kazici, Hilal Celik; Yayla, Muge; Ulas, Berdan; Aktas, Nahit; Kivrak, Hilal
In this study a PdSn based sensor was developed for the determination of benzoic acid (BA) in foods. A carbon (Vulcan XC-72R) supported PdSn catalyst was prepared via polyol method and its surface electronic and chemical properties were investigated by advanced surface analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), X-ray Photoelectron Spectroscopy (XPS), temperature-programmed reduction with H-2 (TPR-H-2) and transmission electron microscopy (TEM). Electrochemical measurements were performed by employing cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques on PdSn/GCE/Vulcan XC-72R electrode. The developed sensor showed a wide linear range up to 10 mM with a 0.77 mu M low limit of detection (LOD) as well as high stability. Further experiments were performed on food samples containing BA to achieve real sample measurements. For real sample measurements, PdSn/GCE/Vulcan XC-72R electrode was used for the determination of BA in different kinds of samples such as mayonnaise, ketchup and carbonated beverages.
An Electrocatalyst for Detection of Glucose in Human Blood: Synergy in Pd-aunps/Gox Surfaces
(Taylor & Francis inc, 2019) Kazici, Hilal Celik; Yayla, Muge
Glucose oxidase (GOx)-based amperometric enzyme electrodes have been the target of substantial research. In this study, new amperometric biosensor for determination of glucose was developed. GOx enzyme was immobilized at bovine serum albumin via entrapment method. For this reason, the optimum conditions of Pd-Au NPs/GOx/C-modified glassy carbon electrode were determined. The electron is directly transferred from glucose to the electrode via the active site of the enzyme. The absence of mediators is the main advantage of such third-generation biosensors. The resulting materials were characterized employing scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. In addition, the effects of glucose concentration, scan rate, temperature, electroactive interference, stability, reusability of the biosensors were discussed. The applicability to blood analysis was also evaluated. The biosensor has a limit of detection for the determination of glucose 0.0014 mM.
The Electromagnetic Wave Absorption Properties of Woven Glass Fiber Composites Filled With Sb2o3 and Sno2 Nanoparticles Doped Mica Pigments
(Wiley, 2022) Akinay, Yuksel; Colak, Bektas; Turan, Muhammet Emre; Akkus, Ihsan Nuri; Kazici, Hilal Celik; Kizilcay, Abdullah Oguz
In this study, the electromagnetic wave absorption properties of woven glass fiber reinforced epoxy composites with Sb2O3 and SnO2 nanoparticles doped mica pigments were investigated. Herein, we synthesized SnO2/mica, Sb2O3/mica, and Sb2O3:SnO2/mica pigments using the sol-gel method. Subsequently, mica pigments filled glass fiber/epoxy composite panels were fabricated with a vacuum assisted resin mold. The phase, crystal, and morphological examinations of particles confirm the deposition of SnO2 and Sb2O3 nanoparticles on the mica surfaces. The electromagnetic wave absorption properties of samples were measured using the S parameters and obtained dielectric data. Sb2O3:SnO2/mica particles display higher complex permittivity and dielectric loss values due to the strong interfacial polarization between conductive nano metal-oxide shells and mica surfaces. According to the calculated reflection loss values, Sb2O3:SnO2/mica particles exhibit superior electromagnetic wave absorption performance with a minimum reflection loss of -25.62 dB for 2.4 mm thicknesses with effective bandwidth between 9.3 and 12.4 GHz. The S parameters of the prepared structural composites with the size of 30 cm x 30 cm x 3 mm was determined by the free-space technique using the transmission line technique. According to the S-12 parameters, filled glass fiber/epoxy composite containing 25 wt% Sb2O3:SnO2/mica show a minimum reflection loss of -20.426 dB at 8.2 GHz with effective bandwidth between 8.2 and 9.67 GHz. These results indicate that Sb2O3:SnO2/mica-filled fiber/epoxy composite is an excellent candidate for the practical application of electromagnetic wave absorbers.
Facile and Rapid Synthesis of Microwave Assisted Pd Nanoparticles as Non-Enzymatic Hydrogen Peroxide Sensor
(Esg, 2017) Sahin, Ozlem; Kivrak, Hilal; Kivrak, Arif; Kazici, Hilal Celik; Alal, Orhan; Atbas, Dilan
Carbon supported Pd catalyst was prepared with microwave-assisted polyol method (M-Pd@C) and investigated sensing activity for non-enzymatic hydrogen peroxide (H2O2). Moreover, M-Pd@C and Pd@C catalyst which synthesized via polyol method (P-Pd@C) were compared to each other in terms of electrocatalytic activity. X-ray diffraction (XRD), X-ray photo electron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate structural and morphological properties of these catalysts. Furthermore, electrochemical measurements were performed via cyclic voltammetry (CV), chronoamperometry (CA) techniques. CV results exhibited that M-Pd/C catalyst showed perfect electrocatalytic activity in terms of reduction of H2O2. M-Pd/C catalyst showed a fast response of less than 7 s with a linear range of 5.0x10(-3)-11.0 mM and a relatively low detection limit of 1.2 mu M amperometric response. M-Pd/C catalyst exhibited great selectivity for detecting H2O2 in the existence of several hindering species such as uric acid and ascorbic acid.
Facile and Rapid Synthesis of Microwave Assisted Pd Nanoparticles as Non-Enzymatic Hydrogen Peroxide Sensor (Vol 12, Pg 762, 2017)
(Esg, 2018) Sahin, Ozlem; Kivrak, Hilal; Kivrak, Arif; Kazici, Hilal Celik; Alal, Orhan; Atbas, Dilan
Hydrogen Production by Using Ru Nanoparticle Decorated With Fe3o4@sio2-Nh2 Core-Shell Microspheres
(Pergamon-elsevier Science Ltd, 2020) Izgi, Mehmet Sait; Ece, M. Sakir; Kazici, Hilal Celik; Sahin, Omer; Onat, Erhan
Noble metals are commonly used in order to accelerate the NH3BH3 hydrolysis for H2 production as heterogeneous catalysts. The nanoparticles (NPs) of these metals can be applied as active catalysts in fluid reactions. Metal NPs included in the core-shell nano- structures emerged as well-defined heterogeneous catalysts. Additionally, unsupported NPs catalysts can be gathered easily among neighboring NPs and the separation/recovery of these catalysts are not efficient with traditional methods. For this reason, here, silica-shell configuration was designed which was functionalized with a magnetic core and amine groups and Ru NPs were accumulated on Fe3O4@SiO2-NH2 surface for H-2 production from NH3BH3. Fe3O4@SiO2-NH2-Ru catalysts demonstrated high catalytic activity as long as it has a hydrogen production rate of 156381.25 mLg(cat)(-1)min(-1) and a turnover frequency (TOF) of 617 mol(H2) mol(cat)(-1)min(-1) towards the hydrolysis dehydrogenation of AB at 30 degrees C. This result is significantly higher than most of the known catalysts. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Hydrogen Production Through the Cooperation of a Catalyst Synthesized in Ethanol Medium and the Effect of the Plasma
(Taylor & Francis inc, 2023) Izgi, Mehmet Sait; Onat, Erhan; Kazici, Hilal Celik; Sahin, Omer
In the present study, nanostructured Ni-B catalysts were successfully prepared in ethanol medium using the chemical reduction method for hydrogen production from the catalytic hydrolysis of sodium borohydride (NaBH4). Ni-B nanostructures were characterized by several analysis methods including XRD, SEM/EDS, FT-IR and BET. The effects of factors such as solution temperature, NaBH4 loadings, catalyst amount and NaOH concentration on the performance of these catalysts in the production of hydrogen from alkaline NaBH4 solutions were investigated in detail. In addition, the Ni-B catalyst prepared in ethanol medium and subjected to plasma for the hydrogen production from the catalytic hydrolysis of NaBH4 was investigated. The Ni-B catalyst prepared in ethanol medium showed maximum hydrogen production rate (1000 mL min(?1)gcatalyst(?1)) which was approximately 2 times higher than the rate obtained from the Ni-B catalyst prepared in water (400 mL min(?1)gcatalyst(?1)) and acethone (550 mL min(?1)gcatalyst(?1)). The Ni-B nanoparticles showed the best catalytic activity at 333?K with a maximum hydrogen production rate of 7134 mL min(?1)gcatalyst(?1) and activation energy of 46.83?kJmol(?1) for the NaBH4 hydrolysis reaction in the Ni-B catalysts prepared in ethanol and subjected to plasma. As the Ni-B catalyst is inexpensive and easy to prepare, it is feasible to use this catalyst in the construction of practical fuel cells for portable and in situ applications.
Microstructured Prealloyed Titanium-Nickel Powder as a Novel Nonenzymatic Hydrogen Peroxide Sensor
(Academic Press inc Elsevier Science, 2018) Kazici, Hilal Celik; Caglar, Aykut; Aydogmus, Tarik; Aktas, Nahit; Kivrak, Hilal
At present, commercial pure Titanium (Ti) and microstructured pre-alloyed Titanium-Nickel (TiNi) powders are employed as a sensitive electrochemical hydrogen peroxide (H2O2) sensor. Surface characterization of these materials are performed by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical characterization is achieved via cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) on Ti and TiNi modified glassy carbon electrode (GCE). The electrochemical behavior of H2O2 at the pure Ti/GCE and microstructure pre-alloyed TiNi/GCE are studied by CV in 0.1 M phosphate buffer solution (PBS) containing as the supporting electrolyte. In addition, CA is employed for the determination of H2O2 at the applied potential of 0 V vs. Ag/AgCl. The sensor has a linear response range of 0.5-17.5 mM with a sensitivity of 280 mu A mM(-1) cm(-2). Moreover, the limit of detection (LOD) and limit of quantification (LOQ) are 0.5 mu M and 1.7 mu M, respectively. The electrochemical sensor exhibits fast and selective responses to H2O2 concentration. The applicability of the sensor is checked using a hair coloring as a real sample with satisfactory results. (C) 2018 Elsevier Inc. All rights reserved.
Novel Activated Carbon Supported Trimetallic Pdcoag Nanoparticles as Efficient Catalysts for the Hydrolytic Dehydrogenation of Ammonia Borane
(Pergamon-elsevier Science Ltd, 2019) Kazici, Hilal Celik; Yildiz, Fikret; Izgi, Mehmet Sait; Ulas, Berdan; Kivrak, Hilal
Activated carbon (AC) supported palladium, cobalt and silver nanoparticle (PdCoAg/AC) catalysts were prepared by in situ reduction of sodium borohydride (NaBH4) and characterized by various techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX), Transmission electron microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The PdCoAg/AC catalyst is active in the hydrolysis of ammonia-borane (AB) even at low temperatures. Compared with mono- (Pd) and bi-metallic (PdCo) nanoparticles, this trimetallic (PdCoAg) structure showed greatly increased catalytic activity for AB hydrolysis. Their hydrolysis completion time was 50 s. This study also included full experimental details of kinetic data to determine the activation parameters (Ea, Delta H and Delta S) for the rate law and the catalytic hydrolysis of AB. In addition, the PdCoAg/AC catalysts had favorable catalytic activity also after seven runs. Hydrogen generation rate (HG), Ea, Delta H and Delta S were obtained at 25 degrees C as 4666.66 mL min(-1)g(-1) (2 mmol AB and 50 mg PdCoAg/AC), 26.836 kJ mol(-1), 29.416 kJ mol(-1) and -108.42 J mol(-1)K(-1), respectively. In addition, the study showed that Pd0.6Co0.2CAg0.2/AC (Pd:Co:Ag atomic ratio = 6:2:2) showed the total turnover frequency (TOF) value of 6624 h(-1). These results demonstrate that the PdCoAg/AC catalyst is a promising alternative in search of the practical application of AB as a hydrogen storage material for fuel cell applications. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
A Novel Study on the Stepwise Electrodeposition Approach for the Synthesis of Pd Based Nanoparticles, Characterization and Their Enhanced Electrooxidation Activities
(Islamic Azad Univ Tonekabon, 2018) Avci, Caglar; Cicek, Fazile; Kazici, Hilal Celik; Kivrak, Arif; Kivrak, Hilal
Herein, a stepwise electrodeposition technique was used to synthesize the Pd based nanoparticles on indium-tin oxide (ITO) electrodes. First of all, Pd nanoparticles were electrodeposited on ITO via one step electrodeposition technique. Furthermore, Au was electrodeposited on Pd. Finally, Co was electrodeposited on Au and Pd electrodeposited ITO electrode via stepwise electrodeposition technique. Characterization of these electrodes was performed by x-ray diffraction (XRD) and scanning electrode microscopy (SEM) techniques. Considering the XRD pattern, well-defined ITO peaks, Pd, and Au fcc structure peaks are clearly visible for Pd based electrodes. On the other hand, Co has two main crystal structures such as face-centered-cubic (fcc) and hexagonal close-packed (hcp) phases. SEM images illustrates that spherical particles were obtained for these Pd based electrodes. Finally, formic acid electrooxidation activities of these electrodes were evaluated and enhanced electrooxidation activities were obtained.
Optimization of the Asymmetric Synthesis of Chiral Aromatic Alcohol Using Freeze-Dried Carrots as Whole-Cell Biocatalysts
(Walter de Gruyter Gmbh, 2016) Kazici, Hilal Celik; Bayraktar, Emine; Mehmetoglu, Ulku
Asymmetric reduction of ketones is an important transformation in organic synthesis, because chiral carbinols are useful bioactive compounds. In this study, bioreduction of acetophenone (ACP) for production of enantiomerically pure (S)-1-phenyl-ethanol was investigated and freeze-dried carrots were used as a source of alcohol dehydrogenases (ADHs). However, production of product was investigated systematically using response surface methodology (RSM). Before RSM, the effects of the initial substrate concentration, reaction time, temperature and pH on the bioreduction were studied. The best results for enantiomeric excesses (ee) and conversion (c) were obtained with >99% and 58%, respectively, for the reaction time 48 h, initial substrate concentration 1 mm, reaction temperature 33 degrees C and pH 7. In the RSM, initial substrate concentration, concentration of plant cell, reaction time and stirring rate were chosen as independent variables. The predicted optimum conditions for a higher ee (>99%) and conversion (57.8%) were as follows: initial substrate concentration, 1 mm; concentration of plant cell, 25 g/l; reaction time, 52 h and stirring rate, 200 rpm. As a result of repeated experiments, the product was obtained as 0.6 mm at this optimum point and the values obtained demonstrated conformity with 0.578 mm value calculated by the model equation.
Production of Precursors for Anti-Alzheimer Drugs: Asymmetric Bioreduction in a Packed-Bed Bioreactor Using Immobilized D. Carota Cells
(Taylor & Francis inc, 2017) Kazici, Hilal Celik; Bayraktar, Emine; Mehmetoglu, Ulku
(S)-1-Phenylethanol derivatives, which are the precursors of many pharmacological products, have also been used as anti-Alzheimer drugs. Bioreduction experiments were performed in a batch and packed-bed bioreactor. Then, the kinetics constants were determined by examining the reaction kinetics in the batch system with free and immobilized carrot cells. Also, the effective diffusion coefficient (De) of acetophenone in calcium alginate-immobilized carrot cells was investigated. Kinetics constants for free cells, which are intrinsic values, are reaction rate V-max - 0.052 mmol L-1 min(-1), and constants of the Michaelis-Menten K-M = 2.31 mmol L-1. Kinetics constants for immobilized cells, which are considered apparent values, are V-max,V- app = 0.0407 mmol L-1 min(-1), K-M,K- app = 3.0472 mmol L-1 for 2 mm bead diameter, and V-max,V- app = 0.0453 mmol L-1 min(-1), K-M,K- app = 4.9383 mmol L-1 for 3 mm bead diameter. Average value of effective diffusion coefficient of acetophenone in immobilized beads was determined as 1.97 x 10(-6) cm(2) s(-1). Using immobilized carrot cells in an up-flow packed-bed reactor, continuous production of (S)-1-phenylethanol through asymmetric bioreduction of acetophenone was performed. The effects of the residence time and concentrations of substrate were investigated at pH 7.6 and 33 degrees C. Enantiomerically pure (S)-1-phenylethanol (ee > 99%) was produced with 75% conversion at 4-hr residence time.
Pt-Ni Trimetallic Nanoparticles Anchored on Graphene Oxide: an Effective Catalyst for Ammonia-Borane Hydrolysis and Direct Electrooxidation of Ammonia-Borane in Alkaline Solution
(Pergamon-elsevier Science Ltd, 2024) Ahmed, Samal M. Mansur; Salman, Firat; Karatas, Yasar; Kazici, Hilal Celik; Gulcan, Mehmet
In this study, graphene oxide supported platin, nickel and cobalt trimetallic nanoparticles (PtNiCo@GO) were prepared by the impregnation/reduction method. The catalytic performances of PtNiCo@GO catalysts prepared with different atomic ratios were investigated for hydrogen production and electro-oxidation of ammonia-borane (AB). For hydrolysis of ammonia-borane, Pt0.8Ni0.1Co0.1@GO catalyst exhibited higher catalytic activity than Pt0.6Ni0.2Co0.2@GO, Pt0.4Ni0.3Co0.3@GO, and Pt0.2Ni0.4Co0.4@GO. The hydrogen generation rate and turnover frequency values were found to be 540 mL min- 1g- 1 and 42.8 min- 1 , respectively, in the experiment conducted at 35 degrees C, 0.5 mmol AB, and 50 mg Pt0.8Ni0.1Co0.1@GO catalyst. The activation parameters (Ea, Delta H # , and Delta S # ) in the catalytic hydrolysis of AB were obtained at 42.22 kJ/mol, 31.95 kJ/mol and-114.82 J/(mol x K), respectively. The effects of the PtNiCo@GO catalyst on AB electro-oxidation were made at a scanning rate of 100 mV/s in the potential range of- 1V/+1V against Ag/AgCl, and chronoamperometry measurements were made at constant potentials of- 0.2V, 0.1V and 0.4V. For cyclic voltammetry and chronoamperometry measurements, 5 mM [Fe(CN)6]3/4 (1 M KCl) redox probe and 1 M NaOH + 50 mM AB solution were used.
Simple Detection of Gluten in Commercial Gluten-Containing Samples With a Novel Nanoflower Electrosensor Made of Molybdenum Disulfide With Comparison of the Elisa Method
(Wiley, 2024) Salman, Firat; Zengin, Adem; Kazici, Hilal Celik
In this study, a new electrochemical sensor based on molybdenum disulfide (MoS2) nanoflowers/glassy carbon electrode (GCE was created for the sensitive detection of gluten. The prepared nanocatalysts were characterized using scanning electron microscopy with energy dispersive spectroscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. The effects of the prepared nanocatalysts, pH value, and dropping amounts on the results were examined in detail. The electrochemical performance of the developed sensor (MoS2 nanoflowers/GCE) was then evaluated using differential pulse voltammetry, and the sensor was found to have significant electrochemical activity against gluten. A substantial linear connection was observed in the range of 0.5-100 ppm of gluten concentration under optimum experimental circumstances, and the detection limit between peak current and gluten concentration was determined as 1.16 ppm. The findings showed that the MoS2 nanoflowers/GCE gluten sensor has exceptional selectivity and stability. Finally, the generated electrochemical sensor was effectively utilized for gluten detection in commercial gluten-containing materials with a detection limit of 0.1652 ppm. Thus, the developed MoS2 nanoflowers/GCE sensor offers a potential method for the detection of other molecules and is a promising candidate for gluten detection in commercial samples.
Synthesis and Characterization of Novel Ti Doped Hexagonal Mesoporous Silica Catalyst for Nonenzymatic Hydrogen Peroxide Oxidation
(Elsevier Science Bv, 2018) Duzenli, Derya; Sahin, Ozlem; Kazici, Hilal Celik; Aktas, Nahit; Kivrak, Hilal
A new electrocatalyst, Ti-HMS was successfully synthesized by sol-gel method employing Ti source tetrabutyl orthotitanate (TBOT) and silica source tetraethyl orthosilicate (TEOS, 99% purity). Ti-HMS catalysts were prepared at varying Ti:Si ratios by employing sol-gel method. Physicochemical properties of these nanoparticles were characterized and confirmed by BET, TG-DTA, XPS, and XRD. Electrochemical properties of Ti-HMS catalysts prepared at varying Ti:Si ratios were examined by cyclic voltammetry (CV) and chronoamperometry (CA) for determination of the oxidation and reduction activity of H2O2. It was observed that the Ti-HMS (Ti:Si = 0.02) electrode exhibits significant oxidation and reduction of H2O2 at applied potentials of 0.65 V and -0.30 V with the addition of H2O2, respectively. The excellent electrocatalytic response to H2O2 is mainly attributed to varying electronic properties with the incorporation of Ti to HMS. (C) 2017 Elsevier Inc. All rights reserved.