Browsing by Author "Caglar, Aykut"

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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.
Alcohol Electrooxidation Study on Carbon Nanotube Supported Monometallic, Pt, Bi, and Ru Catalysts
(Taylor & Francis inc, 2018) Caglar, Aykut; Aldemir, Adnan; Kivrak, Hilal
In the present study, carbon nanotube supported Pt (Pt/CNT), Bi (Bi/CNT), and Ru (Ru/CNT) catalysts are prepared via NaBH4 reduction method for ethanol (C2H5OH), ethylene glycol (C2H6O2), and methanol (CH3OH) electrooxidation. The physical characterization of these as-prepared catalysts is performed by X-ray diffraction (XRD). Furthermore, electrochemical measurements are conducted via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), and linear sweep voltammetry (LSV). Pt/CNT catalyst exhibits the highest catalytic activity and stability compared to Bi (Bi/CNT) and Ru (Ru/CNT) catalysts. It is observed that the electrocatalytic activity of Pt/CNT catalyst for ethylene glycol (C2H6O2) oxidation is higher than its electrocatalytic activities for ethanol (C2H5OH) and methanol (CH3OH) oxidation. Maximum current density of C2H6O2 of Pt/CNT catalyst is about 4 and 5.7 times lower than C2H5OH and CH3OH. Furthermore, electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), and linear sweep voltammetry (LSV) results are in good agreement with CV results in terms of stability and electrocatalytic activity of Pt/CNT. The Pt/CNT catalyst is believed to be a promising anode catalyst for the alcohol fuel cells.
Atomic Molar Ratio Optimization of Carbon Nanotube Supported Pdauco Catalysts for Ethylene Glycol and Methanol Electrooxidation in Alkaline Media
(Springer international Publishing Ag, 2019) Ulas, Berdan; Caglar, Aykut; Kivrak, Arif; Kivrak, Hilal
In this study, carbon nanotube supported Pd, PdAu, and PdAuCo electrocatalysts (Pd/CNT, PdAu/CNT, and PdAuCo/CNT) were synthesized via NaBH4 reduction method at varying molar atomic ratios to investigate their performance for methanol and ethylene glycol electrooxidation in alkaline media. The characterization of the as-prepared catalysts was performed using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, N-2 adsorption-desorption, and small-angle X-ray-scattering analysis. From the physical characterization results, it was seen that PdAuCo/CNT catalysts were successfully prepared. X-ray photoelectron spectroscopy results showed that Pd and Au atoms employed in the preparation of the catalysts exist mainly in their elemental state. X-ray diffraction results indicated the formation of a new phase. Furthermore, the mean particle size of Pd50Au30Co20/CNT was determined as 7.9 and 8.7nm using small-angle X-ray scattering and transmission electron microscopy analyses. Pd50Au30Co20/CNT demonstrated the type V adsorption isotherms with H1-type hysteresis, which indicates the mesoporous structure of the catalyst. Electrocatalytic activity of the catalysts for ethylene glycol and methanol electrooxidation was investigated with cyclic voltammetry and electrochemical impedance spectroscopy. The electrocatalytic activity of Pd50Au30Co20/CNT was determined as 262 and 694mA/mg Pd for methanol and ethylene glycol electrooxidation. In accordance with cyclic voltammetry and electrochemical impedance spectroscopy results, Pd50Au30Co20/CNT possesses the highest electrocatalytic activity for both electrooxidation.
Benzotiyofen@pd as an Efficient and Stable Catalyst for the Electrocatalytic Oxidation of Hydrazine
(Elsevier Sci Ltd, 2022) Kaya, Sefika; Ozok-Arici, Omruye; Kivrak, Arif; Caglar, Aykut; Kivrak, Hilal
An efficient methods for the synthesis of 2-(2,5-dimethylphenyl)-3-iodobenzo[b]thiophene (4) is described, and investigated its anode catalyst performance by using electrochemical methods (CV, CA and EIS). When 2-(2,5dimethylphenyl)-3-iodobenzo[b]thiophene (4) is applied, the specific activity is found as 25.811 mA/cm(2). Interestingly, when Palladium (Pd) is electrochemically deposited on the benzothiophene derivative, the catalytic activity increased the 80.930 mA/cm(2). This result is highest than the current metal based anode catalyst. Moreover, EIS and CA measurements display that Pd doped benzothiophene organic catalyst have high stability, and give the low charge transfer resistance. Energy dispersive X-ray (SEM-EDX), electron microscopy, TEM are used for the determination of its surface morphology. As a result, 2-(2,5-dimethylphenyl)-3-iodobenzo[b]thiophene (4) may be alternative electro-catalysts in fuel cell applications.
Bimetallic Ruthenium-Cobalt Catalyst Supported on Carbon Nanotubes: Synthesis, Characterization, and Application in Electrochemical Sensing of Isoleucine
(Wiley, 2025) Arici, Omruye Ozok; Caglar, Aykut; Najri, Bassam A.; Aktas, Nahit; Kivrak, Arif; Kivrak, Hilal
In this work, a bimetallic Ru-Co catalyst based on carbon nanotubes (Ru-Co/CNT) with a Ru to Co ratio of 95:5 is developed. The catalyst, featuring a total metal loading of 3% on the CNTs, is synthesized using the NaBH4 reduction method. Several analytical analyses are used to detect the properties of the Ru-Co/CNT catalyst. X-ray diffraction (XRD) provides information on crystal structures of the catalysts, high-resolution transmission electron microscopy (HR-TEM) reveals particle size and distribution, inductively coupled plasma mass spectrometry (ICP-MS) measures the elemental composition, and X-ray photoelectron spectroscopy (XPS) use to investigate the chemical oxidation states. In addition, thermal techniques including temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), and temperature-programmed desorption (TPD) are used to recognize the active sites on the catalyst's surface and the acidity. Then, the Ru-Co/CNT catalyst is applied as a sensor for isoleucine amino acid for the first time. It shows high performance with these parameters, sensitivity (0.002 mA cm-2 mm), LOD - limit of detection (0.04 mu m), and LOQ - limit of quantification (0.12 mu m). Moreover, the interferences of common serum blood including (D-glucose, uric acid, ascorbic acid, and L-tryptophan) are studied. The findings indicated that the sensor is applicable to work in complex biological systems.
Carbon Nanotube Supported Cdm(S, Se)/Cdte Anode Catalysts for Electrooxidation of Glucose in Alkaline Media
(Wiley-v C H verlag Gmbh, 2023) Caglar, Aykut; Kivrak, Hilal; Aktas, Nahit
The sequential sodium borohydride (SBH, NaBH4) reduction method was utilized to prepare the 0.1 % CdSe/CNT, 0.1 % CdS/CNT, 0.1 % (CdS-CNT)/CdTe, and 0.1 % (CdSe-CNT)/CdTe catalysts. The XRD, SEM-EDS, TEM, and XPS analyses were used to characterize the catalysts. The electrochemical measurements were examined by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) analyses for glucose electrooxidation. The characterization analyses revealed that the desired structure was formed on the support material. The electrochemical analysis results indicated that the 0.1 % (CdSe-CNT)/CdTe catalyst has higher catalytic activity, stability, and resistance compared to other catalysts with a specific activity of 2.4 mA cm(-2).
Carbon Nanotube Supported Ga@pdagco Anode Catalysts for Hydrazine Electrooxidation in Alkaline Media
(Elsevier Sci Ltd, 2022) Kaya, Sefika; Caglar, Aykut; Kivrak, Hilal
In this study, carbon nanotube supported (CNT) monometallic (Pd), trimetallic (PdAgCo), and multimetallic (Ga@PdAgCo) catalysts in different weight percentages (0.5-10%) are synthesized by the NaBH4 reduction method and characterized transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-mass spectrometry (ICP-MS), and X-ray diffraction (XRD) analytical methods. Ac-cording to the TEM analysis results, while agglomeration doesn't observe for 3% Ga@PdAgCo(80:10:10)/CNT catalyst, agglomeration is observed in certain parts for 7% Ga@PdAgCo(80:10:10)/CNT catalyst. The occurrence of agglomeration has a negative effect on catalytic activity. XRD analysis shows that as metal was added, the diffraction peaks are negatively shifted, thereby forming an alloy. Electrochemical measurements such as cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) are used for the hydrazine electrooxidation activities of the catalysts. The highest specific activity is achieved as 250.39 mA/cm(2) (22592.66 mA/mg Pd) with catalyst. The electrochemical surface area (ECSA) of 3% Ga@PdAgCo/CNT catalysts is also calculated as 1392.43 m(2)/g. The homogeneous distribution of the metals on the support material and the alloy formation has an effect on the catalytic activity for the 3% Ga@PdAgCo(80:10:10)/CNT catalyst. Although Pd is an active metal on its own, the synergistic effect between them as a result of the formation of alloys with different metals and the electronic state change on the catalyst by adding different metals to Pd has a great influence on the catalytic activity. As a result, Ga@PdAgCo/CNT catalyst with its high current value stands out as a new anode catalyst for hydrazine electrooxidation.
Catalytic Electro-Oxidation of Hydrazine by Thymol Based-Modified Glassy Carbon Electrode
(Elsevier Sci Ltd, 2022) Sharif, Kawa Hama; Kivrak, Hilal; Ozok-Arici, Omruye; Caglar, Aykut; Kivrak, Arif
In the present, thymol based new organic compounds (4A , 4B and 4C) are designed and synthesized via Steglich Esterification Reactions and Pd-catalyst Sonogashira Coupling Reactions. After isolation and characterization, thymol based hybrid molecules are used for hydrazine (N2H4) electrooxidation reactions as anode catalysts. A variety of metal based anode catalyst have been reported in literature, but this study may be the first study for thymole based hybrid molecules as an anode catalyst in fuel cells. The performance of hybrid molecules was investigated via cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in hydrazine solution. Hybrid 2-isopropyl-5-methylphenyl-4-oxo-4-(5-(p-tolylethynyl)thiophen-2-yl)butanoate (4C) gives the highest performance as 3.66 mAcm(-2) (17.24 mAmg(-1)). Our results displayed that natural products like thymol derivatives may be new generation anode catalyst for fuel cells, and they may be alternative for expensive Pd and Pt based metal anode catalyst.
Characterization and Electrooxidation Activity of Ternary Metal Catalysts Containing Au, Ga, and Ir for Enhanced Direct Borohydride Fuel Cells
(Springer, 2023) Caglar, Aykut; Kaya, Sefika; Kivrak, Hilal
Carbon nanotube (CNT)-supported catalysts were synthesized by the sodium borohydride (NaBH4) reduction method and characterized by X-ray diffraction, transmission electron microscopy, inductively coupled plasma-mass spectrometry, and X-ray photoelectron spectroscopy analyses. The catalytic activities of the catalysts were examined by cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, and linear sweep voltammetry electrochemical analyses for direct borohydride fuel cells (DBFCs) in NaBH4 solution. The characterization analyses revealed the structure, particle size, and metal ratios of CNT-supported metals. The NaBH4 electrooxidation results indicate that the 3% AuGaIr/CNT catalyst had a specific activity of 5.65 (1529.98 mA mg(-1) Au) mA cm(-2) and higher catalytic activity than the other catalysts. Furthermore, the electrochemical surface area (ECSA) values were obtained by calculating the reduction peak of the metal oxide in the NaOH solution by CV analysis. The ECSA value (128.57 m(2) g(-1)) of 3% AuGaIr/CNT catalyst was much higher than the other catalysts. The 3% AuGaIr/CNT catalyst had faster electron transfer rate with low (961.8 omega) charge transfer resistance (R-ct) and also high stability compared to the other catalysts. The study presents an up-and-coming new type of anode catalyst for DBFC applications. [GRAPHICS] .
The Characterization and Sodium Borohydride Electrooxidation of Novel Carbon Nanotube Supported Copromoted Pd as Anode Catalyst for Fuel Cell
(Wiley, 2022) Caglar, Aykut; Hansu, Tulin A.; Sahin, Omer; Kivrak, Hilal
In the present study, the effect of Co addition on Pd is investigated. Pd/CNT and PdCo/CNT catalysts are prepared via the sodium borohydride (SBH, NaBH4) reduction method. The X-ray diffraction, transmission electron microscope, and inductively coupled plasma-mass spectrometry analyses are performed to characterize the PdCo(70-30)/CNT catalyst. These characterization results reveal that Pd/CNT and PdCo/CNT catalysts are prepared successfully. NaBH4 electrooxidation activities of PdCo/CNT catalysts are examined with electrochemical methods such as cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. PdCo(70-30)/CNT catalyst has 11.52 mA/cm(2) specific activity, 477.18 m(2)/g electrochemical active surface area, and the best electrochemical stability. Pd is a promising catalyst for NaBH4 electrooxidation reaction.
Cnt-Supported Multi-Metallic (Ga@pdagco) Anode Catalysts: Synthesis, Characterization, and Glucose Electrooxidation Application
(Springer, 2023) Kaya, Sefika; Caglar, Aykut; Kivrak, Hilal
Here, Ga@PdAgCo catalysts were prepared by sequential reduction using carbon nanotubes (CNT) as support material. The catalysts at different weight percentages were characterized by inductively coupled plasma-mass spectrometry (ICP-MS), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction (XRD) analytical techniques. Chronoamperometry (CA), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) measurements were applied to examine the glucose electrooxidation performance of the catalysts. Among the catalysts, the 7% Ga@PdAgCo(CNT) multi-metallic catalyst provided the best mass activity and specific activity of 231.08 mA/mg Pd and 2.475 mA/cm(2), respectively. EIS results revealed that the 7% Ga@PdAgCo(CNT) catalyst has a faster electron transfer rate with low (632 omega) charge transfer resistance (Rct). Consequently, the 7% Ga@PdAgCo(CNT) catalyst stands out as a potential anode catalyst for direct glucose fuel cells.
A Comparative Experimental and Density Functional Study of Glucose Adsorption and Electrooxidation on the Au-Graphene and Pt-Graphene Electrodes
(Pergamon-elsevier Science Ltd, 2020) Caglar, Aykut; Duzenli, Derya; Onal, Isik; Tersevin, Ilker; Sahin, Ozlem; Kivrak, Hilal
At present, the graphene is covered on Cu foil with the 5 sccm hexane (C6H14) flow rate, 50 sccm hydrogen (H-2) flow rate, and 20 min deposition time parameters by the CVD method. The graphene on the Cu foil is then covered onto few-layer ITO electrode. Furthermore, the Pt and Au metals are electrodeposited on graphene/ITO electrode with electrochemical method. These electrodes are characterized by Raman spectroscopy and Scanning Electron Microscopy-Energy Dispersive X-Ray analysis (SEM-EDX). The graphene structure is approved via Raman analysis. Au, Pt, and graphene network are openly visible from SEM results. In addition, glucose (C6H12O6) electrooxidation is investigated with cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements. As a result, Pt-graphene/ITO indicates the best C6H12O6 electrooxidation activity with 9.21 mA cm(-2) specific activity (highly above the values reported in the literature). In all electrochemical measurements, Pt-graphene/ITO exhibits best electrocatalytic activity, stability, and resistance compared to the other electrodes. The adsorption of the C6H12O6 molecule is examined theoretically over metal atom (gold and platinum)-doped graphene surfaces using the density functional theory (DFT) method. The interaction between C6H12O6 molecule and OH adsorbed Pt-doped surface is stronger than that of OH adsorbed Au-doped graphene surface thermodynamically according to the reaction energy values. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
A Comparative Study for Sodium Borohydride Dehydrogenation and Electrooxidation on Cerium and Cobalt Catalysts
(Health & Environment Assoc, 2020) Hansu, Tulin Avci; Caglar, Aykut; Sahin, Omer; Kivrak, Hilal
In the present study, Co/CNT and Ce/CNT catalysts are prepared via sodium borohydride (NaBH4) reduction method. Co/CNT and Ce/CNT catalysts are examined to the dehydrogenation and electrooxidation of NaBH4. NaBH4 dehydrogenation activities of these Co/CNT and Ce/CNT catalysts are performed in alkaline environment. 5% Co/CNT catalyst exhibits superior hydrogen evolution compared with other catalysts. Activation energy is calculated using Arrhenius equation. Initial rate for this catalyst is found as 1700 ml H-2 g(cat)(-1) min(-1). As a result of the kinetic calculations, the activation energy of the catalyst is calculated as 44,68775 kj/mol. The degree of reaction (n) is found to be 0.5 by trial and error. In conclusion, 5% Co/CNT catalyst is a promising catalyst for hydrogen production from NaBH4. Cyclic voltammetry (CV) analysis is utilized to examine the electrochemical activity of the catalysts for NaBH4 electrooxidation. 0.1% Co/CNT catalyst has 0.38 mA cm(-2) (3181 mA mg(-1) Co) specific activity.
Composition Dependent Activity of Pdagni Alloy Catalysts for Formic Acid Electrooxidation
(Academic Press inc Elsevier Science, 2018) Ulas, Berdan; Caglar, Aykut; Sahin, Ozlem; Kivrak, Hilal
In the present study, the carbon supported Pd, PdAg and PdAgNi (Pd/C, PdAg/C and PdAgNi/C) electrocatalysts are prepared via NaBH4 reduction method at varying molar atomic ratio for formic acid electrooxidation. These as-prepared electrocatalysts are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), inductively coupled plasma mass spectrometry (ICP-MS), N-2 adsorption desorption, and X-ray electron spectroscopy (XPS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), and lineer sweep voltammetry (LSV). While Pd-50,Ag-50/C exhibits the highest catalytic activity among the bimetallic electrocatalyst, it is observed that Pd70Ag20Ni10/C electrocatalysts have the best performance among the all electrocatalysts. Its maximum current density is about 1.92 times higher than that of Pd/C (0.675 mA cm(-2)). Also, electrochemical impedance spectroscopy (EIS), chronoamperometry (CA) and lineer sweep voltammetry (LSV) results are in a good agreement with CV results in terms of stability and electrocatalytic activity of Pd50Ag50/C and Pd70Ag20Ni10/C. The Pd70Ag20Ni10/C catalyst is believed to be a promising anode catalyst for the direct formic acid fuel cell. (C) 2018 Elsevier Inc. All rights reserved.
Dendrimer Templated Synthesis of Carbon Nanotube Supported Pdau Catalyst and Its Application as Hydrogen Peroxide Sensor
(Wiley-v C H verlag Gmbh, 2019) Alal, Orhan; Caglar, Aykut; Kivrak, Hilal; Sahin, Ozlem
At present, CNT supported catalysts were prepared by two different methods as NaBH4 reduction and dendrimer templated NaBH4 reduction method to observe the effect of preparation method on the sensitivity and activity of H2O2 reduction. Then, CNT supported PdxAuy bimetallic nanocatalysts having various atomic ratio were synthesized via novel dendrimer templated NaBH4 reduction method. The resulting materials were characterized employing XRD and TEM. Crystallite size of 10 %Pd0.7Au0.3/CNTdendrimer was obtained from XRD 17.1 nm and mean particle size obtained from TEM is about 15 nm. Moreover, the electrochemical behavior of these catalysts was characterized by cyclic voltammetry (CV) and chronoamperometry (CA) techniques. PdxAuy bimetallic nanocatalysts have excellent electrocatalytic properties and great potential for applications in electrochemical detection. The sensitivity and the limit of detection values for the prepared sensor with monometallic 10 % Pd/CNTdendrimer catalysts are 219.78 mu A mM(-1)cm(-2) and 2.6 mu M, respectively. However, the sensor constructed with 10 %Pd0.7Au0.3/CNTdendrimer modified electrode has a very high sensitivity of 316.89 mu A mM(-1) cm(-2) with a quick response time of 2 s and a wide linear range of 0.001-19.0 mM. In addition, the interference experiment indicated that the 10 % Pd0.7Au0.3/CNTdendrimer nanoparticles have good selectivity toward H2O2.
Determination of Optimum Pd:ni Ratio for Pdxni100-x/Cnts Formic Acid Electrooxidation Catalysts Synthesized Via Sodium Borohydride Reduction Method
(Wiley, 2019) Ulas, Berdan; Caglar, Aykut; Kivrak, Hilal
The main purpose of this study is to investigate the optimum Pd:Ni molar ratio for carbon nanotube-supported PdNi (PdxNi100-x/CNT) alloy catalysts toward formic acid electrooxidation (FAE). NaBH4 reduction method was employed for the synthesis of Pd90Ni10/CNT, Pd70Ni30/CNT, Pd50Ni50/CNT, and Pd40Ni60/CNT. Synthesized catalysts were characterized by employing advanced surface analytical techniques, namely, X-ray diffraction (XRD), transmission electron microscopy (TEM), N-2 adsorption-desorption, and inductively coupled plasma-mass spectrometry (ICP-MS). The characterization results showed that all catalysts were successfully synthesized at desired molar composition. Pd90Ni10/CNT displayed the highest specific and mass activities with 2.32 mA/cm(2) and 613.9 mA/mg Pd, respectively. Specific activity of the Pd90Ni10/CNT was found approximately 3.6, 2.3, 11.1, and 3.4 times higher than those of Pd70Ni30/CNT, Pd50Ni50/CNT, Pd40Ni60/CNT, and Pd/CNT, respectively. The synergistic effect between Pd and Ni at optimized metal ratio was utilized to obtain an improvement in specific activity. Furthermore, Pd90Ni10/CNT showed the lowest charge transfer resistance (R-ct) and a long-term stability. To our knowledge, this is the first study reporting the optimization of atomic molar composition for PdxNi100-x/CNT catalysts toward FAE.
The Development of Titanium Dioxide Nanotube-Supported Cdte Catalysts for Photocatalytic Enzymatic Glucose Fuel Cell and Response Surface Methodology Optimization
(Elsevier Science Sa, 2024) Caglar, Aykut; Pelen, Yucel Tuncbora; Ulas, Berdan; Zahmakiran, Mehmet; Kivrak, Hilal
Energy is one of the critical needs for human life and well-being. Alternative energy sources are essential due to the increase in energy demand with the rise in population the development of industrialization, and the damage caused by fossil fuels to the environment. Fuel cells, an alternative energy source, are a clean and environmentally friendly technology that converts chemical energy into electrical energy. In this study, titanium dioxide (TiO 2 ) nanotube (TNT)-support CdTe catalysts were synthesized by the wet impregnation (WI) method. Glucose oxidase (GOD) and laccase (LAC) enzymes were modified by incubation on CdTe/TNT catalysts. These enzymatic and non-enzymatic catalysts were characterized by scanning electron microscope-energy dispersive X-ray (SEMEDX) and mapping, X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscope (TEM) analyses. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) analyses were used to examine the activity, resistance, and stability of catalysts for enzymatic photocatalytic glucose electrooxidation. The 3 % CdTe(50-50)-TNT-GOD/GCE electrode exhibited the highest activity, resistance, and stability under UV illumination compared to other electrodes. The modification parameters of the electrodes, incubation time, amount of catalyst ink, and drying time were found to be 136.96 min, 8.94 mu L, and 21.30 min with response surface method (RSM) analysis, respectively. The estimated specific activity value was obtained as 0.754 mA/cm 2 under optimized conditions.
The Effect of Different Carbon-Based Cdte Alloys for Efficient Photocatalytic Glucose Electrooxidation
(Elsevier Science Sa, 2022) Caglar, Aykut; Er, Omer Faruk; Aktas, Nahit; Kivrak, Hilal
The activated carbon (AC), graphene (G), reduced graphene oxide (rGO), carbon nanotube (CNT) supported CdTe photocatalysts at (50-50) atomic molar are synthesized by the sodium borohydride (SBH) method and characterized by the XRD, Micro-Raman, TEM-EDS, XPS, and TPx (TPR, TPO, and TPD) analyses. The CV, CA, and EIS electrochemical analyses are performed to investigate the catalytic activities of catalysts for photocatalytic glucose electrooxidation. Characterization analyses reveal that their electronic structures and surface properties change when carbon materials are doped with metal. The photocatalytic glucose electrooxidation results indicate that the 0.1 % CdTe(50-50)/CNT catalyst exhibited better photocatalytic activity, stability, and resistance than other catalysts both at dark (1.9 mA/cm2) and under UV illumination (2.57 mA/cm2). Therefore, the CNT-supported CdTe catalyst can be said a promising catalyst for direct glucose fuel cells.
The Effect of Titanium Dioxide-Supported Cdse Photocatalysts Enhanced for Photocatalytic Glucose Electrooxidation Under Uv Illumination
(Pergamon-elsevier Science Ltd, 2022) Caglar, Aykut; Kivrak, Hilal; Aktas, Nahit
The wetness impregnation method was used to synthesize 0.1% CdSe/TiO2 photocatalysts with different atomic molar ratios (90-10, 70-30, 50-50, and 30-70). These catalysts were characterized by XRD, SEM-EDX and mapping, TEM-EDS, UV-VIS spectroscopy, fluorescence spectroscopy, XPS, TPR, TPO, and TPD analyses. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) analyses were performed to examine the photocatalytic activity for photocatalytic fuel cells (PFCs) in glucose solution in the dark and under UV illumination. The characterization analyses revealed that anatase TiO2 formed the catalyst and electronic structure and surface properties changed when doped with metal. The photocatalytic glucose electrooxidation (PGE) results demonstrate that the 0.1% CdSe(50-50)/TiO2 catalyst has higher photocatalytic activity, stability, and resistance than other catalysts both in the dark (2.71 mA cm(-2)) and under UV illumination (7.20 mA cm(-2)). These results offer a promising new type of photocatalyst for PFC applications. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Effective Carbon Nanotube Supported Metal (M=au, Ag, Co, Mn, Ni, V, Zn) Core Pd Shell Bimetallic Anode Catalysts for Formic Acid Fuel Cells
(Pergamon-elsevier Science Ltd, 2020) Caglar, Aykut; Cogenli, Mehmet Selim; Yurtcan, Aye Bayrakceken; Kivrak, Hilal
At present, CNT supported Pd and core-shell Pd-based catalysts are synthesized by employing the NaBH4 reduction method to investigate on formic acid electrooxidation (FAEO) activity. These catalysts are characterized by XRD, TEM, HRTEM, and XPS. The XRD results display that the electronic state of catalysts changed by second metal addition to Pd. TEM results reveal that Au and Pd are homogeneously distributed. XPS results of AucorePdshell/CNT catalyst show that Au and Pd atoms used in the preparation of the catalyst are obtained mainly in elemental state. The FAEO activity, stability, and resistance of these catalysts are investigated by employing cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The CV results show that AucorePdshell/CNT catalyst having 16.42 mAcm(-2) specific activity and 4978.23 mA mg(-1) Pd mass activity is better than other catalysts. In addition, the AucorePdshell/CNT (21 m(2)/g) catalyst has better electrochemical active surface area (ECSA) value as 5.25 times compared with Pd/CNT catalyst. Direct formic acid fuel cell (DFAFC) performances are performed at different temperatures for AucorePdshell/CNT and NicorePdshell/CNT catalysts. The specific activity of AucorePdshen/CNT catalyst is 2.5 times higher than the value for NicorePdshell/CNT catalyst. AucorePdshell catalyst is a promising catalyst for DFAFCs. (C) 2019 Elsevier Ltd. All rights reserved.