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A dual functional material: Spirulina Platensis waste-supported Pd-Co catalyst as a novel promising supercapacitor electrode
(Elsevier Sci Ltd, 2021) Karakas, Duygu Elma; Akdemir, Murat; Atabani, A. E.; Kaya, Mustafa
In the present study, Spirulina Platensis waste-supported Pd-Co (SPW-Pd-Co) catalyst was used as an efficient catalyst for the methanolysis reaction of sodium borohydride (NaBH4); moreover, the produced SPW-Pd-Co catalyst was tested as a supercapacitor electrode material for the first time. In this context, the SPW-Pd-Co catalyst was synthesized by the treatment of the Spirulina Platensis waste (SPW) with 1-7 M HCl, 1 mL PdCl2 solution (2% w/w) and 1, 2, 3, 4, and 5 mL CoCl2 center dot 6H(2)O solution (5% w/w). Under optimum conditions, the most active catalyst was obtained by burning with 3 M HCl-Pd-4 mL Co2+ solution at 600 degrees C for 90 min. The maximum rate of hydrogen generation (HGR) obtained at 30 degrees C from the NaBH4 methanolysis reaction was found to be 5497.7 mLmin(-1) gcat(-1), and the catalyst activation energy was found to be 10.32 kJ mol(-1). The gravimetric capacitance of the prepared electrode was calculated as 50 F/g at 2 A/g current density. The capacitance values of the supercapacitor are at a significant level in terms of capacity and the cost.
A novel hazelnutt bagasse based activated carbon as sodium borohydride methanolysis and electrooxidation catalyst
(Pergamon-Elsevier Science Ltd, 2023) Saka, Ceren; Yildiz, Derya; Kaya, Sefika; Caglar, Aykut; Elitok, Dilarasu; Yayli, Elif; Kaya, Mustafa
In this study, activated carbon is produced from defatted hazelnut bagasse at different activation conditions. The catalytic activities of activated carbons are evaluated for NaBH4 methanolysis and electrooxidation. These materials are characterized by N2 adsorption -desorption, FTIR, SEM-EDS and XPS and results show that these materials are prepared successfully. N2 adsorption-desorption results reveal that activated carbon (FH3-500) has the highest BET surface area as 548 m2/g, total pore volume as 0.367 cm3/g and micropore volume as 0.205 cm3/g. On the orher hand, as a result of hydrogen production studies, FH3-500 activated carbon catalyst has the highest initial hydrogen production rate compared to other materials. At 50 & DEG;C, this metal-free activated carbon catalyst has a high initial hydrogen production rate of 13591.20 mL/min.gcat, which is higher than literature values. Sodium borohydride electrooxidation measurements reveal that FH2-500 also has the highest electrocatalytic activity and stability. Hazelnut pulp-based activated carbons are firstly used as a metal-free catalyst in the methanolysis and electrooxidation of sodium borohydride, and its catalytic activity is good as a metal-free catalyst. The results show that the hazelnut pulp-based activated carbon catalyst is promising as a metal-free catalyst for the methanolysis and electrooxidation of sodium borohydride.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
A novel Microcystis aeruginosa supported manganese catalyst for hydrogen generation through methanolysis of sodium borohydride
(Pergamon-Elsevier Science Ltd, 2020) Duman, Fatih; Atelge, M. R.; Kaya, Mustafa; Atabani, A. E.; Kumar, Gopalakrishnan; Sahin, U.; Unalan, S.
In this study, Microcystis Aeruginosa (MA)- microalgae species was used for the first time as a support material with metal ions loading to fabricate a highly efficient catalyst for the hydrogen generation through methanolysis of sodium borohydride (NaBH4). Microalgae was pre-treated with hydrochloric acid (3 M HCl) for 24 h at 80 degrees C. Subsequently, different metal ions (Mn, Co, and Mo) were loaded to the pre-treated samples. Finally, metal-loaded samples were subjected to burning in oven to fabricate the catalyst. Primarily, manganese metal was selected based on the best metal performance. Afterwards, different metal loading ratios, burning temperatures and burning times were evaluated to synthesize the optimal MA-HCl-Mn catalyst. Results showed the optimal conditions as Mn ratio, burning temperature and time as 50%, 500 degrees C and 45 min, respectively. To characterize the catalyst, FTIR, SEM-EDX, XRD, XPS and TEM analyses were performed. Hydrogen generation via methanolysis was performed at various NaBH4 ratio of 1-7.5% while changing concentrations from 0.05 to 0.25 g catalysts with diverge temperatures of (30, 40, 50 and 60 degrees C). The maximum hydrogen generation rate (HGR) by this novel catalyst was found as 4335.3, 5949.9, 7649.4 and 8758.9 mLmin(-1)gcat(-1), respectively. Furthermore, the activation energy was determined to be 8.46 kJ mol(-1). (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
A Novel Tea factory waste metal-free catalyst as promising supercapacitor electrode for hydrogen production and energy storage: A dual functional material
(Elsevier Sci Ltd, 2021) Ozarslan, Saliha; Atelge, M. Rasit; Kaya, Mustafa; Unalan, Sebahattin
In this study, the catalyst produced from tea factory waste (TFW) was used for the first time for hydrogen production by methanolysis of sodium borohydride (NaBH4). The produced material had a dual function as both catalyst and supercapacitor; therefore, it was named 'cap-cat'(capacitor-catalyst) by us. In this context, TFW was treated with acetic acid for 24 h at 80 degrees C. The sample was then subjected to combustion in the oven to synthesize the catalyst. Afterward, the most efficient TFW-CH3COOH catalyst was synthesized by evaluating different acid ratios, burning temperatures and times. The best conditions for the acetic acid ratio, burning temperature, and time were found out 3 M, 300 degrees C, and 60 min. The characterization of the catalyst was done using SEM-EDX, FTIR, XRD analysis. Hydrogen generation experiments from NaBH4 by methanolysis were performed at various catalyst concentrations in the range of 0.05-0.2 g, diverse NaBH4 ratio of 1 to 7.5%, and at different reaction temperatures (30-60 degrees C). The HGR of the synthesized catalyst was recorded as 3096.4, 8367.5, 11227.9, and 23,507 mLmin(-1)g(cat)(-1) for these temperatures (30, 40, 50, and 60 degrees C), respectively. Also the activation energy was calculated as 38.6 kJ mol(-1). Subsequently, the CV (cyclic voltammetry) and charge-discharge curves of the prototypes produced were substantially similar to the supercapacitor curves in the literature. Gravimetric capacitance was found to be 155F/g at a current density of 2 A/g.
A REVIEW FOR ASSESSMENT METHODS OF BLACK TEA PRODUCTION WASTE
(Begell House Inc., 2022) Ozarslan, Saliha; Rasit Atelge, M.; Kaya, Mustafa; Unalan, Sebahattin
Tea production waste occurs during the production of black tea from fresh tea in tea factories, consisting of tea stalk, fiber, and powder, which are unused parts of the tea plant. Tea waste amounts may vary according to the quality of the production process and the harvesting of tea. However, a certain amount of tea waste is obtained every year in the countries that produce tea. Such a large and inexpensive biomass resource is not generally evaluated. There are several ways to take advantage of this biomass source and work on this subject is increasing. In this study, the methods of evaluating tea wastes were researched and the data obtained were transferred with their results. Studies collected under five main topics can be promising for the development of existing studies and new research. This study can be a guide for removing losses from the storage of tea waste and making this biomass economically valuable. © 2022 Begell House Inc.. All rights reserved.
A study on supercapacitor electrode material from trigonal planar and (N?B) dative bond stabilized tetrahedral boron-containing compounds
(Springer, 2023) Kilic, Ahmet; Soylemez, Rahime; AkdemIr, Murat; Kivrak, Hilal DemIr; Kaya, Mustafa; Horoz, Sabit
The present study has revealed that C40H38B2Cl2N4O6, a boron-containing compound, exhibits exceptional electrochemical performance when utilized as an electrode in supercapacitor applications. The specific capacitance values of C40H38B2Cl2N4O6 were found to be significantly higher than that of the traditional electrode material, C15H14BNO2 center dot HCl, in both KOH and Na2SO4 electrolyte solutions. In particular, when tested in KOH, the specific capacitance value of C40H38B2Cl2N4O6 was a staggering 3.74 times greater than that of C15H14BNO2 center dot HCl, demonstrating its exceptional energy storage capabilities. The superior performance of C40H38B2Cl2N4O6 can be attributed to its unique porous structure and high surface area, which enhances its ability to store charge. This research serves as a significant step towards the development of more advanced energy storage devices, and paves the way for C40H38B2Cl2N4O6 to be employed as a promising material in future supercapacitor applications.
Biomass-based metal-free catalyst as a promising supercapacitor electrode for energy storage
(Springer, 2022) Karakas, Duygu Elma; Akdemir, Murat; Imanova, Gunel T.; Kivrak, Hilal Demir; Horoz, Sabit; Kaya, Mustafa
In present study, biomass doped H3PO4-Cat, named as STW-H3PO4-Cat, was used as a catalyst in the methanolysis of sodium borohydride (NaBH4). Spent tea waste (STW) was used for the first time in this study as biomass. The generated existing catalyst was also employed as an active supercapacitor material, demonstrating its dual function. To identify the most active catalyst in the methanolysis of sodium borohydride, the catalyst was functionalized in different H3PO4 concentrations (1-7 M), and different annealing temperatures (200-500 degrees C) and different annealing times (20-80 min). Optimum parameters were determined as 7 M H3PO4, 400 degrees C, and 40 min. The maximum hydrogen production (HPR) value and the activation energy (E-a) were determined as 76,640 mL min(-1) g cat(-1) and 12.03 kJ mol(-1). When the catalyst was investigated in terms of the supercapacitor, the electrode's capacitance at 1 A/g current intensity was found to be 158 F/g utilizing the charge-discharge curve. The catalyst with optimum conditions was structurally and morphologically characterized by Fourier Transform Infrared (FTIR), x-ray diffraction (XRD), and scanning electron microscope (SEM) measurements, respectively.
Boron-containing compounds as a new candidate for supercapacitor electrode: simplified synthesis and structural identification properties
(Elsevier Science Inc, 2023) Akdemir, Murat; Kivrak, Hilal Demir; Kilic, Ahmet; Beyazsakal, Levent; Kaya, Mustafa; Horoz, Sabit
In this study, the performance of two boron-containing compounds, C14H14BNO2 center dot HCl (BCC1) and C38H38B2Cl2N4O4 (BCC2), as electrodes in supercapacitor applications was investigated in the presence of Na2SO4 and KOH electrolyte solutions. The specific capacitance values of the compounds were compared, and the results showed that trivalent boron (BCC1) exhibited higher specific capacitance values than tetravalent boron (BCC2) in both electrolyte solutions. In the presence of Na2SO4 electrolyte solution, the specific capacitance values of the trivalent (BCC1) and tetravalent (BCC2) boron compounds at a current density of 0.75 A/g were 135.21 and 94.87 F/g, respectively, while in the presence of KOH electrolyte, the specific capacitance values of the trivalent (BCC1) and tetravalent (BCC2) boron compounds at a current density of 0.75 A/g capacitance values were determined as 106.62 and 88.25 F/g, respectively. The cycling stability of the electrodes was also studied, and it was found that the capacitance of BCC1 electrode increased gradually over the cycles, while the capacitance of BCC2 electrode decreased. The study suggests that trivalent boron can be a promising material for supercapacitor applications. However, further research is required to optimize the cycling stability of the electrodes and understand the underlying mechanism.
Catalytic activites of a biomaterial (sumac) catalyst in sodium borohyride methanolysis reactions
(Elsevier, 2023) Karakas, Duygu Elma; Kaya, Mustafa; Horoz, Sabit
Biomass waste (sumac) in particular, is an excellent starting point for preparing carbon materials since it is abundant, inexpensive, environmentally beneficial, and renewable. Therefore, the aim of the present study is defatted sumac (DS)-hydrochloric acid (HCl)-cobalt (Co) (DS-HCl-Co) catalyst (it will be used as a catalyst for the first time) in the presence of low activation energy and high hydrogen production rate (HPR). The effect of different parameters such as amount of catalyst, concentration of NaBH4 and tem-perature on HPR value obtained as a result of NaBH4 methanolysis in the presence of DS-HCl-Co catalyst have been investigated. The synthesized catalysts are named DS-HCl (pure) and DS-HCl-Co (supported). While the HPR value (mL*gcat -1 *min -1) obtained as a result of the hydrolysis experiments carried out is 3516.16 for the DS-HCl catalyst, it is 8298.5 for the DS-HCl-Co catalyst. Thus, it should be noted that the HPR value increases approximately 2.36 times in the presence of support material. Our other motivation in the current study is to have low activation energy, which is an important factor that increases catalytic activity. Using the Arrhenius equation, the activation energy for the DS-HCl-Co catalyst is calculated as 31.67 kJ/mol and this value is lower than some reported values when compared to the literature. As a result, it can be said that the DS-HCl-Co catalyst is a unique, inexpensive, and ideal catalyst with high activity values for hydrogen production from alkali hydrides.(c) 2022 Elsevier B.V. All rights reserved.
Chlorella vulgaris microalgae strain modified with zinc chloride as a new support material for hydrogen production from NaBH4 methanolysis using CuB, NiB, and FeB metal catalysts
(Pergamon-Elsevier Science Ltd, 2020) Saka, Cafer; Kaya, Mustafa; Bekirogullari, Mesut
This study aims to produce hydrogen (HG) from sodium borohydride (NaBH4) methanolysis using CuB, NiB or FeB catalysts prepared with a different support material including C. vulgaris microalgae strain modified using zinc chloride (CMS-ZnCl2). The NaBH4 concentration, metal percentage in the supported-catalyst, the optimal ZnCl2 percentage, and temperature effect on the NaBH4 methanolysis were investigated. X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Scanning electron microscopy (SEM) analysis were performed for the CMS-ZnCl2-CuB characterization. Also, the low activation energy (Ea) of 22.71 kJ mol(-1) was found with the supported catalyst obtained. Under the same conditions, nearly 100% conversion was achieved in the reusability experiments repeated five times, but a gradual decrease in catalytic activity was observed after each use. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Defatted spent coffee grounds-supported cobalt catalyst as a promising supercapacitor electrode for hydrogen production and energy storage
(Springer, 2023) Karakas, Duygu Elma; Akdemir, Murat; Atelge, M. R.; Kaya, Mustafa; Atabani, A. E.
The effect of several parameters, such as different Co2+ ratios, burning temperatures, and burning times, was examined by using defatted spent coffee grounds (DSCG) as organic waste to obtain the most effective catalyst for producing hydrogen. Under optimum conditions, the most active catalyst/metal ratio was obtained by burning 50% Co (2+) at 400 degrees C for 90 min. To measure the time-dependent amounts of hydrogen, 0.1 g of DSCG-Co catalyst was dissolved in 10 mL of a methanol solution containing 0.25 g sodium borohydride (NaBH4) at 30 degrees C. The maximum hydrogen generation rate obtained from the methanolysis of NaBH4 at 30 and 60 degrees C was found to be 8749 and 17,283 mL min(-1) gcat(-1), respectively, and the activation energy of the catalyst was found to be 23.2 kJ mol(-1). FTIR, ICP-OES, XRD, BET, and SEM-EDX analyses were performed for the characterization of the prepared DSCG-Co-Cat catalyst. Furthermore, a supercapacitor cell was constructed by using this catalyst as an active substance for electricity storage. The specific capacitance of the electrode at the current density of 1 A/g was calculated as 67 F/g for two-electrode systems. The results of electrochemical analysis of the prepared supercapacitor were found to be similar to the ideal supercapacitor curves. The obtained capacitance values are at very good levels in terms of the capacity and cost factors. The results indicated that the multifunctional capacitor-catalyst material produced by Co-doped waste coffee could constitute an important element in a hybrid system that includes capacitor and catalyst systems that can be installed in the future. [GRAPHICS] .
The Effect of Microwave Irradiation on a Co-B-based Catalyst for Hydrogen Generation by Hydrolysis of NaBH4 Solution
(Taylor Francis- Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2015) Şahin, Ömer; Kaya, Mustafa; İzgi, M.Sait; Saka, Cafer
A Co-B-based catalyst was prepared under microwave irradiation for hydrogen generation by hydrolysis of NaBH4 solution. The activity of Co-B catalyst for hydrogen generation was studied in comparison with another Co-B catalyst prepared by the known methods. The results show that Co-B catalyst reduced prepared under microwave irradiation was quick and was completed in only 17 min, while the Co-B catalyst produced in a known method was slow and was completed in 27 min. The hydrogen generation from the hydrolys of NaBH4 with Co-B catalyst was investigated depending on NaBH4 and NaOH concentrations in solution, temperature, microwave applying time, and microwave applying power. Hydrolysis kinetics of NaBH4 were investigated at a temperature range of 30–50°C and zero-order kinetics were applied to the obtained data.
Effects of different temperatures and additives on the metastable zone width precipitation kinetics of NaBO2
(Maik Nauka/Interperiodica/Springer, 2014) Kaya, Mustafa; Ceyhan, Ayhan Abdullah; Sahin, Omer
In this study, the sodium metaborate, which is applicable in various industrial areas, and its metastable zone width that is very important for its production by crystallization, and its nucleation are investigated to obtain the necessary thermodynamic parameters. The polythermal and isothermal method has been used for the measurement of metastable zone width. Metastable zone width of NaBO2 has found at 9A degrees C at average and cooling rate do not have any effect on it. In addition, the effect of sodium metaborate on the hydrogen storage capacity of sodium borohyride solutions that is known as one of the best hydrogen sources today is investigated at the various concentrations of sodium borohyride in the medium. Results have shown that three different areas emerged as the percentage of NaBH4 in the solution increased.
Efficient hydrogen generation from the NaBH4 methanolysis by waste material: banana peel
(Springer Japan Kk, 2022) Karakas, Duygu Elma; Kaya, Mustafa; Horoz, Sabit
The aim and originality of our current study are to use the original biomass (activated carbon) obtained by functionalizing waste banana peels (commonly found in Turkey) with acid in NaBH4 methanolysis and to examine its contribution to the hydrogen generation rate (HGR). Our study consisted of three stages. In the first stage, the optimum conditions were determined by examining the catalyst under parameters such as different acid types, different carbonization temperatures, and different carbonization times. Thus, based on the maximum HGR value, the optimum conditions were determined as H3PO4, 600 degrees C, and 40 min. In the second step, the effects of parameters such as acid concentration, NaBH4 concentration, catalyst amount, and temperature on HGR were investigated. As a result of methanolysis experiments (condition: catalyst amount: 100 mg, acid amount: 30%, NaBH4 concentration: 2.5%, temperature: 30 degrees C, carbonization temperature: 400 degrees C, and carbonization time: 40 min.), the maximum HGR value, the reaction completion time and activation energy were found as 65,625 mLmin(-1)gcat(-1), 0.233 min, and 4.56 kJ/mol, respectively. It was observed that the obtained activation energy was lower than that of some catalysts available in the literature. In addition, the structural and morphological examination of the banana peel (catalyst) with high HGR and low activation energy revealed that the acid functionalization process was successfully carried out.
Enhanced Photocatalytic Hydrogen Production on Cd-, Te-, Se-, and S-Doped Titanium Dioxide Catalysts
(Springer, 2023) Kaya, Sefika; Saka, Ceren; Caglar, Aykut; Kaya, Mustafa; Kivrak, Hilal
Herein, cadmium (Cd)-, tellurium (Te)-, selenium (Se)-, and sulfur (S)-doped titanium dioxide (TiO2) support material catalysts are prepared via incipient wetness impregnation. Hydrogen generation performances of the prepared catalysts from sodium borohydride (NaBH4) by methanolysis are investigated. Experimental studies are carried out under ultraviolet (UV) illumination and in the dark. The highest initial hydrogen generation rate is reached on 0.1% Cd/TiO2 catalyst under UV illumination. The optimum catalyst, sodium borohydride, and methanol amounts and temperature parameters affecting the initial hydrogen generation rate are investigated and obtained as 0.025 g, 0.150 g, 2 mL, and 60 degrees C, respectively. The initial hydrogen generation rate of 0.1% Cd/TiO2 catalyst is 16130.64 mL/min.gcat in optimum conditions. The activation energy of the reaction with the 0.1% Cd/TiO2 catalyst is calculated by carrying out kinetic studies. The activation energy is 22.48 kJ/mol. X-ray diffraction (XRD), electron microscopy with energy-dispersive x-ray spectroscopy (SEM-EDX), inductively coupled plasma mass spectrometry (ICP-MS), x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) analytical techniques are performed to characterize the catalysts. The results show that TiO2 catalysts doped with Cd, Te, Se, and S, which are cheaper than noble metals, are promising for the production of hydrogen from NaBH4 by methanolysis under UV illumination.
Evaluating organic waste sources (spent coffee ground) as metal-free catalyst for hydrogen generation by the methanolysis of sodium borohydride
(Pergamon-Elsevier Science Ltd, 2020) Kaya, Mustafa
In this study, organic waste sources (spent coffee ground (SCG)) is used as metal-free catalyst in comparison with conventional noble-metal catalyst materials for hydrogen generation based on the methanolysis of sodium borohydride solution. Spent coffee ground (SCG) is used as a metal-free catalyst for the first time as treated with different chemicals. The aim is to synthesize the metal-free catalyst that can be used for the production of hydrogen, a renewable energy source. SCG, which was collected from coffee shops, was used for preparing the catalyst. To produce hydrogen by sodium borohydride (NaBH4) methanolysis, SCG is pretreated with different chemical agents (H3PO4, KOH, ZnCl2). According to the acid performances, the choice of phosphoric acid was evaluated at different mixing ratios (10%, 20%, 30%, 40%, 50%, 100%) (w/w), different temperatures (200, 300 and 400 degrees C) and burning times (30, 45, 60 and 90 min) for the optimization of SCG-catalyst. A detailed characterization of the samples were carried out with the aid of FTIR, SEM, XRD and BET analysis. In this study, the experiments were generally carried out effectively under ambient temperature conditions in10 ml methanol solution containing 0.025 g NaBH4 and 0.1 g of the catalyst. The hydrogen obtained in the experimental studies was determined volumetrically by the gas measurement system. When evaluating the hydrogen volume, different NaBH4 concentrations, catalyst amount and different temperature effects were investigated. The effect of the amount of NaBH4 was investigated with 1%, 2.5%, 5%, and 7.5% ratio of NaBH4 while the influence of the concentration of catalyst was carried-out at 0.05, 0.1, 0.15, and 0.25 g catalysts. Four different temperatures were tested (20, 30, 40, 50 and 60 degrees C) to explore the performance of the catalyst under different temperatures. The experiments by using SCG-catalyst treated with H3PO4 reveal that the best acid ratio was 100% H3PO4. The maximum hydrogen production rate with the use of SCG-catalyst for the methanolysis of NaBH(4 )was found to be 8335.5 mL min(-1) gcat(-1). Also, the activation energy was determined to be 9.81 kJ mol(-1). Moreover, it was discovered that there was no decline in the percentage of converted catalyst material. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Exploring the Triple Applications of Ag/PMAc-g-CNT Nanocomposites in Enhancing HER, OER and Supercapacitor Performance
(Springer, 2024) Kaya, Sefika; Caglar, Aykut; Akdemir, Murat; Kivrak, Hilal Demir; Horoz, Sabit; Kaya, Mustafa
The research aims to investigate the potential of using Ag/PMAc-g-CNT as a high-efficient catalyst for overall water splitting and supercapacitor applications. The results of Tafel slope measurements for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) showed that the Ag/PMAc-g-CNT catalyst had a lower Tafel slope of 22.62 mV dec-1 and 62.74 mV dec-1, respectively, compared to the other electrocatalysts. Additionally, the capacitance value of the Ag/PMAc-g-CNT catalyst was found to be 41.87 F at 0.5 A/g current density which is much higher than that of the Ag/PMAc catalyst. These results demonstrate that the Ag/PMAc-g-CNT catalyst has superior properties in terms of electrochemical activity, stability and energy storage capacity, making it a promising material for both water splitting and supercapacitor applications.
High-efficiency catalyst for water splitting and supercapacitor applications: the promising role of Ni/PMAc-g-CNT
(Springer Heidelberg, 2023) Caglar, Aykut; Kaya, Sefika; Avci Hansu, Tuelin; Akdemir, Murat; Demir Kivrak, Hilal; Horoz, Sabit; Kaya, Mustafa
In this study, we investigated the use of electrocatalysts, PMAc, PMAc-g-CNT, Ni/PMAc, and Ni/PMAc-g-CNT for water splitting and supercapacitor applications. Our results showed that the Ni/PMAc-g-CNT catalyst exhibited superior properties in terms of electrochemical activity, stability, and energy storage capacity. The Tafel slope for OER was found to be 471.25 mV dec(-1), which was lower than other catalysts studied. The capacitance value of the Ni/PMAc-g-CNT catalyst was 35.23 F/g at 0.5 A/g current density, which was higher than the Ni/PMAc catalyst. These findings provide a novel and detailed insight into the performance of these catalysts and suggest that the Ni/PMAc-g-CNT catalyst is a promising material for both water splitting and supercapacitor applications.
Highly efficient Co-B catalysts with Chlorella Vulgaris microalgal strain modified using hydrochloric acid as a new support material for hydrogen production from methanolysis of sodium borohydride
(Pergamon-Elsevier Science Ltd, 2019) Bekirogullari, Mesut; Kaya, Mustafa; Saka, Cafer
In this study, we report for the first time the use of C. Vulgaris microalgal strain containing cellulose in the modified form to be used as a catalyst support material for the production of hydrogen from the methanolysis reaction of sodium borohydride (NaBH4). Acetic acid, phosphoric acid, and hydrochloric acid (HCI) at different concentrations and impregnation times were used for the protonation of cellulose in the microalgal strain. The cobalt ions were added to this modified support material and, C.Vulgaris microalgal strain-supported Co-B catalyst was obtained. XRD, BET, FTIR, XPS, ICP-MS, TEM, and SEM-EDX analysis were carried out for characterization of the sample. The maximum hydrogen production rate from the methanolysis reaction of NaBH(4 )with this catalyst was 13215 ml min( )(-1)g(cat)(-1) In addition, the activation energy was determined as 25.22 kJ/mol. At the same time, reusability studies of the microalgal strain-supported Co-B catalyst were performed and it was found that there was no decrease in the % conversion for this catalyst, while the activity decreased. XRD, BET, FTIR, XPS, ICP-MS, TEM, and SEM-EDX. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Highly efficient CoB catalyst using a support material based on Spirulina microalgal strain treated with ZnCl2 for hydrogen generation via sodium borohydride methanolysis
(Wiley-Hindawi, 2019) Kaya, Mustafa; Bekirogullari, Mesut; Saka, Cafer
In the study, a different support material based on ZnCl2-treated Spirulina microalgal strain (SSMS-ZnCl2) was prepared. Then, the SSMS-ZnCl2-CoB catalysts were used as a very efficient catalyst to produce hydrogen via the SB methanolysis. The SB concentration, Co metal percentage in the supported-catalyst, ZnCl2 concentration, ZnCl2 impregnation time, temperature, and reusability experiments were performed. The maximum hydrogen generation rates (HGR) for the SSMS-ZnCl2-CoB at 30 degrees C and 60 degrees C were found to be 9266 and 36 366 mL min(-1) g(cat)(-1), respectively. In addition, TOF values for 30 degrees C and 60 degrees C were calculated 33 and 110 L center dot mol(H2)center dot mol(Co)(-1)center dot min(-1) for the methanolysis of SB with SSMS-ZnCl2-CoB catalyst. The activation energy was 31.13 kJ mol(-1). The reusability experiments were repeated five times under the same conditions. The almost 100% conversion was obtained at each use. XRD, FTIR, TEM, SEM-EDX, and ICP-MS analysis were performed for SSMS-ZnCl2-CoB characterization.

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