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Characterization of La-alloyed CdS QDs synthesized by the successive ionic layer adsorption and reaction (SILAR) technique
(Springer, 2018) Ekinci, Arzu; Sahin, Omer; Horoz, Sabit
In this present study, the photovoltaic, structural, elemental and optical properties of La-alloyed CdS quantum dots (QDs) synthesized at room temperature using the successive ionic layer adsorption and reaction (SILAR) technique were investigated for the first time. For La-alloyed CdS QDs with different La concentrations, incident photons to current efficiency (IPCE) was measured and the optimum La concentration giving the best solar cell efficiency was determined as 1%. Characterization procedures were then performed to determine the structural and optical properties of La-alloyed CdS QDs with 1% La. As a result, La-alloyed CdS QDs with 1% La have been proposed as promising materials for photovoltaic applications.
Chemical bath deposition of Co-doped PbS thin films for solar cell application
(Springer, 2020) Ekinci, Arzu; Sahin, Omer; Horoz, Sabit
Co-doped PbS thin films with different Co concentrations were synthesized by cost-effective chemical bath deposition technique. The main purpose of this study is to determine thin film which has the best photovoltaic efficiency by examining the photovoltaic properties of Co-doped PbS with different Co concentrations. To investigate photovoltaic properties, incident photon-to-current efficiency (IPCE) and current density (J)-voltage (V) measurements were performed. The second stage of our study is to characterize the properties of Co-doped PbS which has the best photovoltaic efficiency value. As a result of the characterization processes, the information about the crystal structure, crystallite size and energy band gap of Co-doped PbS was obtained. When the photovoltaic efficiency values obtained in the first stage of our study were taken into consideration, it was clearly observed that the Co-doped metal significantly improved the photovoltaic properties of the PbS.
Co-La-B Katalizörünün Sentezlenmesi ve Yakıt Pilinde Kullanılması
(2020) Horoz, Sabit; Ekinci, Arzu; Şahin, Ömer
Bu çalışmada, bir hidrojen jeneratörü tasarlamak için Co-La-B katalizörü kullanılarak katalizör miktarı, NaOHkonsantrasyonu, NaBH4 konsantrasyonu ve çözelti sıcaklığı gibi parametrelerin hidrojen üretim hızı üzerindekietkisi incelenmiştir. Hidrojen üretim reaksiyonu için aktivasyon enerjisi 40,3 kJ mol-1 olarak hesaplanmıştır. CoLa-B katalizörünün varlığında elde edilen hidrojen üretim sistemi kullanarak, polimer elektrolit membran yakıthücresi (PEMFC) yığını çalıştırılmıştır. Yerinde üretilen hidrojen, bir PEM yakıt pilinde kullanılarak o yakıt pilineait verim hesaplanmıştır. Üretilen hidrojenin zamanla akım ve gerilim üzerindeki değişimleri incelenmiştir.Yerinde üretilen hidrojenin tek hücreli PEM yakıt pilinde kullanılması ile akım ve gerilim değerlerinden, 0,65W’lık bir güç değeri hesaplanmıştır. PEM yakıt pili uygulamasında güce ve ideal voltaja göre ortalama verimdeğerleri sırasıyla %62 ve %79 olarak bulunmuştur. Elde edilen sonuçlardan, Co-La-B katalizörünün PEM yakıtpili uygulamaları için ideal bir katalizör olduğu söylenebilir.
Designing copper-doped zinc oxide nanoparticle by tobacco stem extract-mediated green synthesis for solar cell efficiency and photocatalytic degradation of methylene blue
(Taylor & Francis Inc, 2024) Ekinci, Arzu; Sahin, Omer; Kutluay, Sinan; Horoz, Sabit; Canpolat, Gurbet; Cokyasa, Mine; Baytar, Orhan
This study presents the green synthesis of copper-doped zinc oxide (Cu-doped ZnO) nanoparticles using tobacco stem (TS) extract. The environmentally friendly synthesis method ensures distinct features, high efficiency, and applicability in various fields, particularly in solar cell technology and photocatalytic applications. ZnO nanostructures are investigated due to their unique properties, cost-effectiveness, and broad range of applications. The nanoparticles are synthesized with varying Cu concentrations, and their structural, morphological, and compositional characteristics are thoroughly analyzed. The Cu-doped ZnO nanoparticles exhibit improved properties, such as increased surface area and reduced particle size, attributed to the incorporation of Cu dopants. The green synthesis approach using TS extract serves as a stabilizing agent and avoids the toxicity associated with chemical methods. Characterization techniques including SEM, TEM, EDX, FTIR, and XRD confirm the successful synthesis of the nanoparticles. Photocatalytic degradation studies reveal that the 5% Cu-doped ZnO exhibits the highest photocatalytic activity against methylene blue, attributed to synergistic effects between Cu and ZnO, including oxygen vacancy and electron-hole pair recombination rate suppression. The photocatalytic mechanism involves the generation of superoxide and hydroxyl radicals, leading to methylene blue degradation. Furthermore, the Cu-doped ZnO nanoparticles demonstrate promising photovoltaic performance, with the optimal efficiency observed at a 5% Cu concentration. The study suggests that Cu-doped ZnO has the potential to enhance solar cell efficiency and could serve as an alternative material in solar cell applications. Future research should focus on refining Cu-doped ZnO for further improvements in solar energy conversion efficiency The successful synthesis of Cu-doped ZnO nanoparticles from tobacco stem extract suggests an environmentally friendly approach. The photocatalytic degradation studies demonstrate the superior activity of 5% Cu-doped ZnO against methylene blue, attributed to synergistic effects between Cu and ZnO. Cu-doped ZnO has the potential to significantly enhance solar cell efficiency. The demonstrated photocatalytic and photovoltaic activities of Cu-doped ZnO open avenues for further research in optimizing their performance for practical applications in solar energy technologies and sustainable energy production.
Effect of a novel metal-free green synthesis catalyst on the positive role of microwave irradiation in hydrogen production from the hydrolysis of sodium borohydride
(Elsevier, 2024) Ekinci, Arzu; Sahin, Omer; Baytar, Orhan
This study demonstrates the synthesis of hydrochar, a high-value material, from watermelon seed husk, a lowvalue waste material, using the hydrothermal synthesis method. The microwave power effect plays an important role in the use of metal-free and environmentally friendly catalysts for the hydrolysis of sodium borohydride. The XRD, BET, SEM, and FTIR analyses characterized the catalyst. X-ray diffraction revealed the catalyst structure to be cellulosic. The surface area and total pore volume were 1.063 m2/g and 0.0195 cm3/g, respectively, in BET analysis. According to the IUPAC classification, the catalyst conformed to the type III isotherm. This study investigated how good the catalyst for the hydrolysis of sodium borohydride was when it was exposed to microwave irradiation at different microwave powers, solution temperatures, and catalyst amounts. The Langmuir-Hinshelwood and nth-order kinetic models calculated the activation energies to be 82.192 and 83.35 kJ/mol, respectively. The use of bio-waste hydrochar as a catalyst in the hydrolysis of sodium borohydride in the microwave environment shows promising results in the search for metal-free catalysts.
Effect of environmentally friendly and efficient metal-free hydrochars as catalysts on sodium borohydride hydrolysis
(Elsevier Sci Ltd, 2023) Baytar, Orhan; Sahin, Omer; Ekinci, Arzu
Environmentally friendly, metal-free catalysts are important to synthesize and use, as are catalysts made from biomass-based. This study aims to obtain hydrochars from pine cones and rheum ribes shells by the hydrothermal method and use this hydrochar as a catalyst in sodium borohydride hydrolysis.The characterization of the synthesized catalyst hydrochars was carried out by XRD, BET, SEM, EDX, ICP-OES and FTIR analyses. X-ray diffraction analysis of pinecone hydrochar and rheum ribes shells hydrochar has revealed that they are both amorphous and crystalline in structure. The BET surface areas of the two hydrochars are 1.6 m2/g and 19.01 m2/g, respectively. The activity of hydrochars on the hydrolysis of sodium borohydride was evaluated under microwave irradiation at different temperatures, catalyst amounts, and different microwave powers. The hydrolysis kinetics of NaBH4 in the presence of pine cone and rheum ribes shells hydrochars cat-alysts were determined according to the nth-order and the Langmuir-Hinshelwood kinetic models. The activation energies for the rheum ribes shells and pine cone hydrochars catalysts were calculated to be 88.29 kJ/mol and 78 kJ/mol, respectively. It was concluded that hydrochar prepared from waste material extract through the eco-friendly green synthesis method is promising for the hydrolysis of NaBH4.
Effect of microwave irradiation on PEMFCs anode and cathode catalysts
(Springer, 2023) Sahin, Oemer; Yilmaz, Adem; Ekinci, Arzu
This study explored the effects of PtCo/C catalysts modified by microwave radiation as anode and cathode catalysts in proton exchange membrane (PEM) fuel cells. The PtCo/C catalyst was synthesized using sodium borohydride and formic acid-reducing agents by a chemical reduction method. The structural properties of PtCo/C and modified PtCo/C catalysts were analyzed by XRD analysis. The composition and distribution of these alloys in Vulcan XC-72R carbon were determined by SEM techniques. The electrochemical properties of the catalysts were evaluated by CV studies. The tafel slope b values for PtCo/C and modified PtCo/C catalysts were calculated as 84 mV/dec and 43 mV/dec when used as cathode catalysts, and 54 mV/dec and 41 mV/dec when used as anode catalysts, respectively. The power density values were calculated as 52 mW/cm(2) and 58 mW/cm(2) when PtCo/C and modified PtCo/C were used as cathode catalysts, and 33.48 mW/cm(2) and 52.08 mW/cm(2) when used as anode catalysts, respectively. The power density rises by 12% when the modified PtCo/C catalyst is employed as the anode catalyst and by 56% when it is used as the cathode catalyst, as compared to PtCo/C catalysts.
Effects of H2/O2 and H2/O3 gases on PtMo/C cathode PEMFCs performance operating at different temperatures
(Pergamon-Elsevier Science Ltd, 2023) Sahin, Omer; Akdag, Abdurrahman; Horoz, Sabit; Ekinci, Arzu
This study reported the activity of catalysts synthesized from platinum and molybdenum alloys in different atomic ratios and used as cathode electrocatalysts in the PEMFC. The structural properties of PtMo/C and Pt/C catalysts were analyzed by XRD analysis. The composition and distribution of these alloys in Vulcan XC-72R Carbon were determined by SEM and EDX techniques. CV studies assessed electrochemical properties such as ORR and ECSA activity. The performance of PEMFC cathodes that supplied pure hydrogen and ox-ygen was examined using polarization curves at different temperatures. Another way to improve the cathodic reaction is to use ozone as a potent oxidizing agent. It was measured that the OCV of the H-2/O-3 PEM fuel cell was 1.60 V, much greater than the open circuit voltage of the traditional H-2/O-2 PEM fuel cell. The PtMo/C catalyst achieved its highest power density of 137 mWcm(-2) at 70 degrees C, 128 mWcm(-2) at 60 degrees C, 101 mWcm-2 at 50 degrees C, and 85 mWcm(-2) at 40 degrees C when exposed to H-2/O-2. As the temperature of the cell was raised, it was seen that the catalyst's catalytic activity increased.
The effects of plasma treatment on electrochemical activity of Co–W–B catalyst for hydrogen production by hydrolysis of NaBH4
(Elsevier, 2013) Ekinci, Arzu; Şahin, Ömer; Saka, Cafer; Avcı, Tülin
A plasma treatment of Co–W–B catalyst increases the rate of hydrogen generation from the hydrolysis of NaBH4. The catalytic properties of Co–W–B prepared in the presence of plasma have been investigated as a function of NaBH4 concentration, NaOH concentration, temperature, plasma applying time, catalyst amount and plasma gases. The Co–W–B catalyst prepared with cold plasma effect hydrolysis in only 12 min, where as the Co–W–B catalyst prepared in known method with no plasma treatment in 23 min. The activation energy for first-order reaction is found to be 29.12 kJ mol-1.
Effects of plasma treatment, La content and temperature on the La-Ni-Mo-B catalysts for hydrogen production from NaBH4 hydrolysis
(Taylor & Francis Ltd, 2017) Sahin, Omer; Ekinci, Arzu; Balbay, Asim; Saka, Cafer
La-Ni-Mo-B catalysts with 0.15, 0.21 and 0.30-mol La molar ratio are prepared by a mixing method followed by a plasma treatment, characterised and investigated for hydrogen production via sodium borohydride hydrolysis. XRD, SEM, Brunauer-Emmett-Teller and FTIR techniques are used for characterising the catalysts. The hydrogen generation rate at 60 degrees C compared to 30 degrees C using La-Ni-Mo-B under the same conditions is significantly different. The effect of temperature, plasma application time and different plasma gases on hydrogen generation from NaBH4 hydrolysis reaction using La-0.21-Ni-Mo-B catalyst is investigated. It was found that the plasma-treated catalysts exhibited low activation energy for zero order (58 kJ mol(-1)).
Facile synthesis and comprehensive characterization of Ni-decorated amine groups-immobilized Fe3O4@SiO2 magnetic nanoparticles having enhanced solar cell efficiency
(Springer, 2021) Ece, Mehmet Sakir; Ekinci, Arzu; Kutluay, Sinan; Sahin, Omer; Horoz, Sabit
In this study, the synthesis and comprehensive characterization of Fe3O4@SiO2 magnetic nanoparticles (MNPs) immobilized with L-Arginine decorated with nickel (Ni) was achieved, and their ability in solar cell efficiency was evaluated. Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@L-Arginine and Fe3O4@SiO2@L-Arginine-Ni MNPs were prepared by co-precipitation and sol-gel methods. The structural, morphological, optical and textural properties of the prepared MNPs were clarified by Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-Ray (EDX), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET), Thermal Gravimetric Analysis (TGA) and Ultraviolet-Visible (UV-Vis) analyzes. From the BET data, it is understood that the specific surface area of the prepared Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Arginine MNPs is 60.85, 28.99 and 29.84 m(2)/g, respectively. From the pore size distribution determined by Barrett-Joyner-Halenda (BJH) method, it was understood that the pore radius of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Arginine MNPs were in the range of mesopore and the average pore radius was equal to approximately 11.03, 9.11 and 28.45 nm, respectively. It is assumed that the half pore widths calculated by the density functional theory (DFT) method of the prepared of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Arginine MNPs are 5.58, similar to 0.88, and similar to 17.98 nm, respectively. The energy band gap of the prepared MNPs with spinel structure was determined as approximately 3.10 eV. In addition to the structural, morphological, optical and textural properties, the photovoltaic properties of the prepared MNPs were examined. Au/CuO/Fe3O4@SiO2@L-Arginine-Ni/ZnO/SnO2:F solar cell device was created by using existing Fe3O4@SiO2@L-Arginine-Ni MNPs as buffer layer. The power conversion efficiency (%) of the prepared Fe3O4@SiO2@L-Arginine-Ni MNPs based solar cell device was calculated as 1.84 %. This numerical result shows that the prepared Fe3O4@SiO2@L-Arginine-Ni MNPs can be used as a promising buffer layer in a solar structure.
Facile “Green” synthesis of a novel Co–W–B catalyst from Rheum ribes shell extract and its effect on sodium borohydride hydrolysis: Kinetic mechanism
(Elsevier Ltd, 2024) Ekinci, Arzu; Genli, Nasrettin; Şahin, Ömer; Baytar, Orhan
The present investigation aimed to assess the influence of the Co–W–B NPs catalyst on the process of sodium borohydride hydrolysis. The study involved the synthesis of Co–W–B NPs through the utilization of an eco-friendly green synthesis extract derived from the Rheum ribes shell in conjunction with the chemical reduction technique for catalyst production. The investigation of catalysts' structure and surface morphology was conducted through the utilization of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) techniques. The average particle size was determined to be 35 nm in TEM analysis. The presence of Co–W–B nanoparticles and their elemental composition % were determined through EDX analysis, revealing values of 63.9% (Co), 31.89% (C), 1.75% (B), and 2.46% (W) within the nanoparticle. The manufactured Co–W–B catalyst's use for hydrolysis of sodium borohydride was studied under various conditions, including different concentrations of NaOH and NaBH4, different amounts of catalyst, and different temperature parameters. The hydrogen production rate for the Co–W–B NPs catalyst in NaBH4 hydrolysis was determined to be 5367 mLg?1min?1 at 30 °C. The study involved the determination of TOF values for a catalyst composed of Co–W–B NPs, which were subjected to varying temperatures. The activation energies were determined through the utilization of the n-th order and Langmuir-Hinshelwood kinetic models and subsequently calculated using the Arrhenius equation, resulting in values of 35.36 and 31.70 kJ/mol, respectively. The values of enthalpy and entropy, ?H and ?S, were determined through the utilization of Eyring's equation, 18.49 kJ/mol and ?80.7 J/mol.K, respectively. © 2023 Hydrogen Energy Publications LLC
Green synthesis of Co-based nanoparticles from Rheum ribes shell extract and determination of the effect of their activity on sodium borohydride hydrolysis
(Springer Heidelberg, 2024) Baytar, Orhan; Sahin, Omer; Genli, Nasrettin; Ekinci, Arzu
This study investigated the effect of Co(0) and Co-B NP catalysts synthesized by the green synthesis method using Rheum ribes shell extract on the NaBH4 hydrolysis process for the first time, and determined the role of the green synthesis method in the catalyst activity. The investigation of the structure and surface morphology of the catalysts was evaluated using XRD, SEM-EDX, TEM, FTIR, and XPS analyses. The effect of catalysts on NaBH4 was examined at different catalyst amounts, different NaBH4/NaOH concentrations, and different temperature values. The Co(0) and CoB NPs catalysts achieved the greatest HGR values at a solution temperature of 30 degrees C, with values of 7326 mLmin-1g-1cat and 12,524 mLmin-1g-1cat, respectively. The calculated activation energies for Co(0) and Co-B NPs catalysts are 37.68 kJmol-1 and 21.28 kJmol-1, respectively. The green synthesis method synthesized Co(0) and Co-B catalysts significantly increased hydrogen production activity compared to the cobalt-based catalysts synthesized by other methods.
Green synthesis of copper oxide and manganese oxide nanoparticles from watermelon seed shell extract for enhanced photocatalytic reduction of methylene blue
(Taylor & Francis Inc, 2023) Ekinci, Arzu; Kutluay, Sinan; Sahin, Omer; Baytar, Orhan
NOVELTY STATEMENT The copper oxide (CuO) and manganese oxide (MnO) nanoparticles (NPs) were synthesized from watermelon seed extract by the green synthesis method. The watermelon seed shell, which is left as waste to the environment, has been transformed into a product with high added value. The particle sizes of CuO and MnO NPs were determined to be in the range of 15-97 and 6-51 nm, respectively. The photocatalytic performance of the CuO and MnO NPs used as catalysts were investigated for the photocatalytic reduction of methylene blue in an aqueous solution. In the photocatalytic reduction of methylene blue, sodium borohydride (NaBH4) was used as the reducing agent. The CuO and MnO NPs were capable to remove 96.58% (in 70 min) and 96.60% (in 140 min) of methylene blue, respectively. It was determined that UV light was effective in the photocatalytic reduction of methylene blue with NaBH4. The reaction rate coefficient for the photocatalytic reduction of methylene blue with CuO and MnO NPs was calculated as 0.0426 and 0.0235 min(-1), respectively.
Green synthesis of NiO from watermelon seed shell extract for the evaluation of H2 production from NaBH4 hydrolysis and photocatalytic reduction of methylene blue
(Elsevier, 2023) Baytar, Orhan; Ekinci, Arzu; Sahin, Omer; Kutluay, Sinan
In the study, NiO nanoparticles were successfully prepared from watermelon seed shell extract as a reducing agent by the green synthesis method. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet-visible (UV-vis) were used for the characterization of NiO nanoparticles to evaluate the structural and morphological identifications. The NiO nanoparticles were applied for the first time as a photocatalyst in the photocatalytic reduction of methylene blue and as a catalyst in H2 production from NaBH4 hydrolysis. In the photocatalytic reduction of methylene blue with NaBH4 as a reducing agent, it was observed that there was no colour change for 24 h without catalyst, and 98 % of methylene blue was reduced in 13 min in the presence of NiO nanoparticles. The photocatalytic reduction kinetics of methylene blue was investigated using the pseudo-first-order model, and the rate constant was found to be 0.382 min-1. H2 production from NaBH4 hydrolysis using the NiO nanoparticles was investigated in terms of the effect of microwave radiation ambient and temperature. The kinetics of H2 production from NaBH4 hydrolysis was studied by applying the nth-order kinetic model. The H2 production rate (rH2), activation energy (Ea) and reaction order (n-value) were found to be 660 mLH2 min- 1 gcat kJ mol-1 and 0.59, respectively. This study revealed that NiO nanoparticles prepared by an eco-friendly green synthesis method can be used as an alternative potential catalyst for the photocatalytic reduction of methylene blue and H2 production from NaBH4 hydrolysis.
High catalytic activity of cobalt nanoparticles synthesized by ultrasonic spray method in sodium borohydride hydrolysis
(Pergamon-Elsevier Science Ltd, 2024) Buyukkanber, Kaan; Ekinci, Arzu; Sahin, Omer
Enhancing the hydrolysis reaction of NaBH4 for efficient hydrogen production requires the development of effective catalysts. In this study, the solution particles used for nanoparticles synthesized using the ultrasonic spray (US) method were produced for the first time in N2 at room temperature in the gas and liquid intermediate phases. It also brings a new approach to synthesizing low-cost and efficient catalysts using ultrasonic spray technology. The proposed method involves US the CoCl2 solution into the NaBH4 solution to reduce cobalt, producing catalysts for hydrogenation. This innovative approach pioneers a gas-liquid interface reaction for metal reduction. The resulting catalysts were characterized using SEM, XRD, XPS, TEM, BET and FT-IR analysis. The influence of NaOH/NaBH4 concentration, solution temperature, and catalyst amount on hydrogen production rate was investigated, and kinetic parameters were analyzed to understand the reaction kinetics better. The hydrogen production rates of US-Co and reduction method (RM) Co catalysts under the same conditions were calculated as 3995 mlH2/min.gcat and 1245 mlH2/min.gcat, respectively. The activation energy values calculated for the NaBH4 hydrolysis of the US-Co catalyst using the nth-order and Langmuir-Hinshelwood kinetic models are 46.75 kJ/mol and 46.87 kJ/mol, respectively. Therefore, it can be concluded that the LangmuirHinshelwood kinetic model is consistent with the nth-order kinetic model. Experimental results showed that the ultrasonic spray method is very effective in producing active metal catalysts, offering promising opportunities for catalytic advances.
Highly improved solar cell efficiency of Mn-doped amine groups-functionalized magnetic Fe3O4@SiO2 nanomaterial
(Wiley, 2021) Kutluay, Sinan; Horoz, Sabit; Sahin, Omer; Ekinci, Arzu; Ece, Mehmet Sakir
Herein, magnetic Fe3O4@SiO2 nanomaterial functionalized with amine groups (Fe3O4@SiO2@IPA) doped with manganese (Mn) was prepared, characterized and used for solar cell application. Fe3O4@SiO2@IPA-Mn was prepared via the co-precipitation and sol-gel techniques. Energy-dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) measurements were performed to examine the structure of Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@IPA and Fe3O4@SiO2@IPA-Mn. General morphology and textural properties of the prepared magnetic nanomaterials were clarified by Brunauer-Emmett-Teller (BET) and scanning electron microscopy (SEM). In addition, Ultraviolet-visible (UV-Vis) spectroscopy and thermal gravimetric analysis (TGA) were used to have a knowledge about the energy band gap and thermal behavior of the prepared magnetic nanomaterials. The energy band gap of Fe3O4@SiO2@IPA with spinel structure was determined as approximately 2.48 eV. It was understood that Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@IPA showed type IV-H3 hysteresis cycle according to IUPAC. From the BET data, it was determined that the specific surface areas of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@IPA were 60.85, 28.99 and 40.41 m(2)/g, respectively. The pore size distributions of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@IPA were calculated as 8.55, 1.53 and 1.70 nm, respectively, by the BJH method. Also, it was observed that the dominant pore widths of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@IPA were calculated similar to 5.58, similar to 0.88 and similar to 17.92 nm, respectively, by the DFT method. Au/CuO/Fe3O4@SiO2@IPA-Mn/ZnO/SnO2: F solar cell device was created using existing Fe3O4@SiO2@IPA-Mn as a buffer layer. The power conversion efficiency (%) of Fe3O4@SiO2@IPA-Mn based solar cell device was calculated as 2.054. This finding suggest that Fe3O4@SiO2@IPA-Mn can be used as a promising sensitizer in solar cell technology. Moreover, in this study, the effectiveness of the modification of manganese (one of the transition metals, which is cheap and easily available) with magnetic nanomaterials in the use of solar cell technology was demonstrated for the first time.
Hydrogen Production by Hydrolysis of NaBH4 with Cr-Ni-W-B Catalyst: Effects of Cold Plasma and Chromium Content
(Walter De Gruyter Gmbh, 2016) Sahin, Omer; Saka, Cafer; Ekinci, Arzu; Balbay, Asim
In this study, the hydrogen generation from the hydrolysis of NaBH4 with Cr-0.0125-Ni-W-B catalyst prepared in the presence of cold plasma was investigated based on Cr content, NaBH4 concentration, NaOH concentration, temperature, plasma applying time and plasma gases effects. The results of the activity tests indicate that the choice of Cr and the catalyst composition greatly influenced the activity as well as the selectivity for hydrogen generation from the hydrolysis of NaBH4. The Cr-0.0125-Ni-W-B catalyst was treated with argon, nitrogen and carbon dioxide plasma at different treatment times. The catalysts were characterized using SEM, BET surface area measurement and XRD.
Hydrolysis of sodium borohydride solutions both in the presence of Ni-B catalyst and in the case of microwave application
(Pergamon-Elsevier Science Ltd, 2020) Ekinci, Arzu; Cengiz, Ebuzer; Kuncan, Melih; Sahin, Omer
In this study, the nickel boron (Ni-B) catalyst was studied in the microwave environment for hydrogen production from the hydrolysis of a sodium borohydride solution to release H-2. The catalytic activity of the Ni-B catalyst was measured by hydrogen production from the hydrolysis of sodium borohydride. The catalytic properties of the Ni-B catalyst in the microwave medium were examined by considering parameters such as NaOH concentration, NaBH4 concentration, catalyst amount, temperature, and microwave power. Thus, the results obtained from the experiments carried out with Ni-B catalyst both in non-microwave and microwave media were compared. In the experiments, under microwave irradiation, the best result was the release of hydrogen gas from the Ni-B catalyst by applying 100 W of microwave energy at 40 degrees C. Activation energy values were calculated using the reaction rate constants obtained at different temperatures in the nth order kinetic model and the Langmuir - Hinshelwood model. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Improved catalytic activity in PdCo nanocatalysts synthesized via ultrasonic spray method for PEMFC applications
(Pergamon-Elsevier Science Ltd, 2024) Ekinci, Arzu; Buyukkanber, Kaan; Akdag, Abdurrahman; Sahin, Ohmer
The current emphasis of research on PEM fuel cells is the exploration of novel, resilient, and very efficient electrocatalysts that do not rely on platinum, while also ensuring long-term stability. This study aimed to enhance the catalytic activity as cathode electrocatalysts by synthesizing Palladium-cobalt alloy nanoparticles using the ultrasonic spraying (US) technique and then dispersing them over a carbon black substrate. The ultrasonic spray method produces crystalline catalysts in the liquid-vapor interface reaction without requiring additional energy. Analyses were performed using XRD, SEM, EDS, XPS and TEM to determine the structural and morphological properties of the nanocatalysts. XRD analysis determined the average particle size of USCo-Pd/C and US-CoPd/C nanocatalysts to 1.37 nm and 1.09 nm, respectively. CV measurements identified ECSA values for USCo-Pd/C and US-CoPd/C as 7.1 m(2)/gPd and 8.9 m(2)/gPd. The relative performance ranking of cathode electrocatalysts for PEM fuel cells was evaluated at a cell temperature of 70 C-degrees. The order of reactivity for the catalysts is as follows: US-CoPd/C > USCo-Pd/C > PdCo/C > Pd/C. The better electrochemical performance of USCo-Pd/C and US-CoPd/C nanocatalysts as cathode catalysts in PEM fuel cell applications, in comparison to Pd/C and PdCo/C catalysts, can be attributed to the modification of the electronic structure of palladium. This modification depends on the synthesis of cobalt and palladium metals together using the US method and the synergistic effect of the catalysts.

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