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Öğe Aerogel based nanogenerators: Production methods, characterizations and applications(Wiley, 2020) Korkmaz, Satiye; Kariper, I. AfsinThanks to the nanogenerators known as state-of-the-art energy collecting devices, the mechanical energy in every environment can be converted into electrical energy. Some studies on the improvement of the performance of triboelectric and piezoelectric nanogenerators that convert mechanical energy to electrical energy revealed that aerogels brought significant outcomes in the development of nanogenerators. Aerogels, the lightest solid material known, provides a large surface area as the contact area of the nanogenerators, its adjustable porosity allows to improve electronic properties of the nanogenerators, showing its significance in electronics once again. At the same time, the use of aerogels, which is the best candidate in terms of flexibility and mechanical strength required in wearable electronics, in the production of nanogenerators continues to attract the attention of researchers. This study includes an introduction of aerogels and the discussions on the studies involving aerogel based nanogenerators. In the paper, the studies in the literature, focusing on the advantages of aerogel based nanogenerators and their current applications were collected. Three different types of aerogel nanogenerators production were observed to be produced. They are all based on aerogel electrodes produced from different materials, and the paper outlines them with basic working principles. This classification of aerogel nanogenerators and outlining the results will make a significant contribution to the literature and will be a good source for researchers who want to work in this field.Öğe BaTiO3-based nanogenerators: fundamentals and current status(Springer, 2022) Korkmaz, Satiye; Kariper, I. AfsinPiezoelectric nanogenerators (PENG) collect energy from the environment and biomechanical movements and convert this mechanical energy into electrical energy. They have become an attractive alternative to traditional rechargeable batteries for providing electrical power low energy portable devices. As PENGs became the center of attention in robots, wearable devices, medical equipment, and many other fields, the development of piezoelectric materials has become mandatory. This review reviews the basic information, structure, properties, and preparation methods of Barium Titanate, one of the most important PENGs, its development in recent years, and the progress towards high energy generation.Öğe Direct utilization of radioactive irradiated graphite as a high-energy supercapacitor a promising electrode material(Elsevier Sci Ltd, 2022) Karimi-Maleh, Hassan; Kariper, I. Afsin; Karaman, Ceren; Korkmaz, Satiye; Karaman, OnurConsidering ever-increasing energy needs, resulting in the depletion of fossil fuels and, as a corollary, global warming, the adoption of green technologies and the development of sophisticated energy storage and conversion technologies are imperative. Although the supercapacitors have garnered a lot of attention as a highperformance energy storage solution, it is still crucial to engineer novel electrode materials via low-cost and facile, scalable methods while maintaining their enhanced power density and cycle stability. In this work, it was aimed to design and engineer graphite (GRs)-based electrode low-cost materials to be utilized as a highperformance supercapacitor. This study is of great importance in terms of it is one of the first works which offered a facile pathway to fabricate GRs-based electrode materials via the irradiation approach, as well as direct utilization of them in supercapacitor cells. In this regard, various graphite-based samples were prepared by irradiation with several point beam radiation sources, including Am-241, Sr-90, Co-60, and Na-22. The electrochemical active surface area and microcrystalline sizes of GRs were fine-tuned via the type of the radiation source. X-Ray Diffraction (XRD), Raman spectroscopy, and Scanning Electron Microscopy, Energy Dispersive X Ray (SEM-EDX) techniques were employed to assess the physicochemical features of the as-obtained GRs. The electrochemical behaviors of the samples were further tested in 3.0 M H2SO4 aqueous electrolyte via the coin-cell type supercapacitor cells based on GRs. The maximum specific capacitance was achieved for the GR-Sr90 sample, which was of the largest electrochemically active surface area (0.3087 cm(2)), as 483.20F.g(-1) at a current density of 0.2 A.g(-1), which was roughly 5 fold of the non-irradiated GR sample. At the end of the 5,000th CV cycle, the capacitance retention of GR-Sr90 was determined to be 97.40 %. The energy density and power density values of assembled supercapacitor cells based on GRs were found to be comparable to the commercial energy storage systems. All these striking results reveal that the suggested scalable fabrication method will shed an innovative light on the development and engineering of energy storage systems based on low-cost graphite-based electrode materials.Öğe Effect of pH on the structural and optical properties of polycrystalline ZnSe thin films produced by CBD method(World Scientific Publ Co Pte Ltd, 2019) Tezel, Fatma Meydaneri; Kariper, I. AfsinIn this study, zinc selenide (ZnSe) thin films were produced on glass substrate by using chemical bath deposition (CBD) method at 80 degrees C, from aqueous solutions of zinc sulphate and sodium selenosulphide, which were produced using solid selenium as the E selenium source. The optical and structural properties of ZnSe thin films were investigated at room-temperature. The pH of the chemical bath, in which ZnSe thin films were immersed, were changed between pH:8-11. Optical properties of the films, including extinction coefficient, refractive index, reflectance, absorbance, transmittance, dielectric constants and optical density values were calculated using absorbance and transmittance measurements determined using a Hach Lange 500 spectrophotometer, in 300-1100 nm wavelength range. Optical bandgap values were obtained from transmittance and absorbance spectra ranged between 2.12 and 2.49 eV. According to XRD results, it was found that the films have polycrystalline structure and they exhibited different film thicknesses depending on phase and pH changes.Öğe THE EFFECTS OF pH ON STRUCTURAL AND OPTICAL CHARACTERIZATION OF IRON OXIDE THIN FILMS(World Scientific Publ Co Pte Ltd, 2017) Tezel, Fatma Meydaneri; Ozdemir, Osman; Kariper, I. AfsinIn this study, the iron oxide thin flims have been produced by chemical bath deposition (CBD) method as a function of pH onto amorphous glass substrates. The surface images of the flims were investigated with scanning electron microscope (SEM). The crystal structures, orientation of crystallization, crystallite sizes, and dislocation density i.e. structural properties of the thin flims were analyzed with X-ray diffraction (XRD). The optical band gap (E-g), optical transmission (T%), reflectivity (R%), absorption coeffcient (alpha), refraction index (n), extinction coeffcient (k) and dielectric constant (epsilon) of the thin flims were investigated depending on pH, deposition time, solution temperature, substrate temperature, thickness of the flims by UV-VIS spectrometer.Öğe Engineering of GO/MWCNT/RuO2 ternary aerogel for high-performance supercapacitor(Elsevier Sci Ltd, 2022) Karimi, Fatemeh; Korkmaz, Satiye; Karaman, Ceren; Karaman, Onur; Kariper, I. AfsinIt is of great importance to fabricate high-performance electrode materials via a facile fabrication pathway to be utilized in energy storage systems, specifically in supercapacitors. Herein, ruthenium(IV) oxide (RuO2) was decorated onto the nanocomposite of graphene oxide (GO) and functionalized multi-walled carbon nanotubes (MWCNT) via straight forward production pathway for the first time, and the resultant nanostructure was then characterized physicochemically via x-ray diffraction spectroscopy (XRD), Fourier transform infrared spectros-copy (FTIR), field-emission scanning electron microscope (FESEM), and energy dispersive X-ray analysis (EDX). The fabricated nanostructure was employed as the electrode material to develop a high-energy symmetrical supercapacitor cell. The electrochemical performance of the as-assembled supercapacitor was assessed by cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) techniques. The highest specific capacitance was achieved as 514.9F.g(- 1) at a current density of 0.5 A.g(- 1). Moreover, even at a high current density of 10.0 A.g(- 1), the specific capacitance value was computed still as high as 329.3F.g(- 1). The superior capacitance retention feature (94.38 % at the end of 5,000th consecutive CV cycles) revealed the outstanding electrochemical activity of the electrode material. The attained energy density of 37.96 W.h.kg(- 1) (at a power density of 8.33 kW.kg(- 1)) implied the potential application of the proposed supercapacitor cells as a high-energy system.Öğe Fog harvesting against water shortage(Springer Heidelberg, 2020) Korkmaz, Satiye; Kariper, I. AfsinFog harvesting is a sustainable, simple and cost-effective technique to collect water from the air. Clean, safe and drinkable water resources are created by installing this fog harvesting apparatus in deserts, in arid regions and in countries with high population density. Here we review principles and recent developments in fog harvesting.Öğe Glass formation, production and superior properties of Zr-based thin film metallic glasses (TFMGs): A status review(Elsevier, 2020) Korkmaz, Satiye; Kariper, I. AfsinRegarding the metallic glasses, the analysis of their unique structural, thermal and mechanical properties in the form of thin films metallic glasses (TFMGs) indicates a new class of materials with superior properties. These characteristics made TFMGs indispensable and promising in many areas. Recently, Zr-based TFMGs have particularly attracted the attention with their good mechanical and fatigue properties, corrosion resistance and thermal stability. In this review, we briefly talked about bulk and thin film forms of metallic glasses and reviewed recent significant and interesting results about TFMG with Zr content. In the last part of the study, the production and advantages of Zr-based bulk and thin film metallic glasses were discussed.Öğe Graphene and graphene oxide based aerogels: Synthesis, characteristics and supercapacitor applications(Elsevier, 2020) Korkmaz, Satiye; Kariper, I. AfsinGraphene and graphene-based materials have a high potential, especially in energy storage technology. Thanks to the three-dimensional (3D) structures developed with this material, their importance in the production and application of energy storage devices has increased. Studies on supercapacitor applications of graphene-based aerogels have begun to arouse interest in recent years. In this study, recent studies on aerogel supercapacitors, in which researchers have shown great interest, have been compiled and collected. In this study, production methods and properties of graphene oxide, properties and production of aerogels, production and applications of graphene/graphene oxide aerogels are discussed. In this way, the data is presented and discussed in an organized way for the researchers who study or who want to study in this field.Öğe The impact of pH on the structural, surface, electrical and optical properties of nanostructured PbSe thin films(Iop Publishing Ltd, 2019) Tezel, Necmi Serkan; Tezel, Fatma Meydaneri; Kariper, I. AfsinThis study involves PbSe deposits fabricated on glass substrates at different pH. Some optical properties of these deposits, including reflectance, extinction coefficient, refractive index, and dielectric constant were calculated by using absorbance values at room temperature with UV spectrophotometer according to wavelength. The surface properties and compositions were examined by SEM and EDX, respectively. Surface tensions were measured by Zisman Method, and obtained to be 39.0, 42.1, 43.1 and 39.1 mNm(-1) for pH: 8, 9, 10 and 11 values, respectively. The optical band gaps (Egap) were calculated as 2.17, 1.82, 1.77 and 2.27 eV for pH: 8, 9, 10 and 11, respectively. PbSe deposits' electrical resistivity was measured via four-point probe technique depending on deposits thicknesses, and they were found to be 65.27, 26.21, 39.87 and 36.03 Omega cm for pH: 8, 9, 10 and 11, respectively.Öğe Investigation of photodetector performance based on methylammonium lead halide perovskites/reduced graphene oxide heterostructure(Springer, 2023) Jaf, Hawre Azad Othman; Pakma, Osman; Ozden, Sadan; Kariper, I. Afsin; Korkmaz, Satiye; Guneser, M. TahirThe remarkable advancements achieved in the field of perovskite materials have spurred the development of photodetectors, playing a pivotal role in diverse optoelectronic applications. Among these, heterostructured perovskite-based photodetectors have emerged as a superior choice, surpassing the performance capabilities of their pure perovskite counterparts. This study presents the fabrication of an rGO/MAPbI3 heterostructured photodetector via the spin-coating technique. A comprehensive structural analysis of the device was conducted, encompassing X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Current-voltage (I-V) and capacitance-voltage (C-V) measurements, performed under various illumination conditions as well as in the absence of light, unequivocally demonstrate the photodiode characteristics of the device. The data reveal a direct correlation between illumination intensity and both current and capacitance, substantiating the photodetector's responsiveness. Notably, the calculated photosensitivity values S (%) of the Al/Gra/p-Si device, measured under a reverse bias of - 2 V, exhibit a range, varying from 42,000 to 79,300%. Furthermore, observations suggest a decrease in series resistance with increasing illumination intensity, while the ideality factor and barrier height values show an opposite trend. In addition, frequency-dependent measurements divulge a decrease in capacitance as the frequency escalates. These findings can be elucidated through the interactions involving light-induced charges at the interface between the rGO oxide layer and the semiconductor, coupled with the dynamic fluctuations in quasi-Fermi levels within the state of equilibrium.Öğe Irradiated rGO electrode-based high-performance supercapacitors: Boosting effect of GO/rGO mixed nanosheets on electrochemical performance(Elsevier Sci Ltd, 2022) Karaman, Onur; Kariper, I. Afsin; Korkmaz, Satiye; Karimi-Maleh, Hassan; Usta, Metin; Karaman, CerenSupercapacitors are seemed to be one of the most promising choices as an energy storage system. However, there is still a gap in enhancing its energy density values and cyclic stabilities throughout a facile approach. Herein, it was aimed to propose a facile and effective way to fabricate high-energy supercapacitor electrode material based on reduced graphene oxide (rGO) nanostructure. Bearing this in mind, the bulk rGO powder was irradiated by various beam sources including Co-60, Am-241, Na-22, and Sr-90, and the resultant irradiated rGO samples were utilized as the electrode active material to fabricate symmetrical supercapacitor cells. The irradiated rGO samples were characterized both physicochemically and electrochemically. The physicochemical characterizations revealed that as a consequence of the irradiation, both GO and rGO nanosheets were formed in the resultant powder and the d-spacing of the graphene nanosheets were expanded. The highest electrochemical performance metrics were acquired for Sr-90 irradiated rGO electrode-based supercapacitor cell with the specific capacitance value of 585.44F.g ? 1 at 0.2 A.g ? 1, and outstanding capacitance retention performance of 97.14% for the 5000th CV cycles at 200 mV.s ? 1. Moreover, the energy density and power density values were comparable to other commercial energy storage systems such as lead-acid and nickel-metal hybrid batteries. Hence, it can be speculated that these pioneering breakthroughs could pave the way for cutting-edge high-energy supercapacitors based on rGO-derivatives with superior electrochemical performance metrics, as well as engineering of highperformance rGO-based materials to be employed in various energy applications.Öğe A NEW APPROACH TO PREPARE POLYCRYSTALLINE PbTe-TeO THIN FILM, AND ITS OPTICAL, STRUCTURAL, SURFACE AND ELECTRICAL CHARACTERIZATION(World Scientific Publ Co Pte Ltd, 2021) Tezel, Fatma Meydaneri; Kariper, I. AfsinIn this study, PbTe thin film was produced on glass substrates, via chemical bath deposition (CBD) method, with 3-h deposition time at 50(circle)C. The produced thin film had polycrystalline structure; TeO2, PbTe, PbTe3 and Te2O5 crystals that were characterized by X-ray diffraction (XRD) had tetragonal, cubic, tetragonal and monoclinic crystal structures, respectively. Reflectivity (R; in %), optical transmission (T; in %), optical bandgap (Eg), absorption, dielectric constant (epsilon), extinction coefficient (k) and refractive index (nr) of polycrystalline PbTe thin film obtained using UV-Vis spectrophotometer were 29.87%, 19.41%, 3.30eV, 0.6, 3.72, 0.05 and 4.08, respectively. Grain sizes of polycrystalline PbTe thin film varied between 8.79nm and 52.55nm. Optical and electrical conductivities of the crystals according to photon energy were calculated using optical parameters, whereas their surface morphology was characterized by scanning electron microscopy (SEM). The thickness of polycrystalline PbTe thin film was measured by atomic force microscopy (AFM), and found to be 900nm.Öğe A new process to synthesize CrSe thin films with nanosize by CBD method(Iop Publishing Ltd, 2019) Tezel, Fatma Meydaneri; Kariper, I. AfsinIn this study, CrSe thin films were produced by using a new variation of chemical bath deposition (CBD) on glass substrates at different pH values, namely pH: 8, 9, 10 and 11. Some optical properties of these films including T% (transmittance), R% (reflectance), n (refractive index), k (extinction coefficient) and epsilon(1) and epsilon(2) (real and imaginary parts of dielectric constants) for pH: 8, 9, 10 and 11 were found as (82.89, 80.00, 78.54, 79.05%), (3.76, 5.32, 4.08, 5.44), (1.48, 1.59, 1.48, 1.60), (0.055, 0.079, 0.127, 0.116) and (1.33, 1.47, 1.21,1.52) and (0.87, 0.33, 0.12, 0.14) at 550 nm wavelength. Surface morphologies of thin films were examined by SEM. Film thicknesses were measured to be 34, 44, 50 and 104 nm by AFM, and the optical band gap (E-gap) were calculated as 3.14; 3.72; 3.71 and 3.74 eV for pH: 8, 9, 10 and 11, respectively. Optical conductivity variation of CrSe thin films were calculated as a function of frequency for pH: 8, 9, 10 and 11, respectively. The usage areas of these films in optoelectronic applications were discussed.Öğe Optical properties of selenium sulfide thin film produced via chemical dropping method(Springer, 2018) Kariper, I. Afsin; Ozden, Sadan; Tezel, Fatma MeydaneriThis paper describes the production of selenium sulfide (SeS2) crystalline thin film on commercial glass substrates, via chemical bath deposition. Transmittance, absorption, dielectric constant and refractive index of the produced films were investigated by UV/VIS Spectrum. It was found that changes occurred on the characteristics of the films and they were determined as a function of selenium sulfide concentration, which varied between 2x10(-3) and 5x10(-3)M. The structure of the film was analyzed using FTIR spectrum. The calculated refractive index values fell between 1.5 and 1.6, whereas the transmission ratio of the films was around 80-90%. Moreover, a peak in the reflectance was observed at 320-330nm for all investigated samples. The highest dielectric constant for the films was obtained at the deposition concentration of 0.005M. This study is believed to be useful for thin film production.Öğe Optical, electrical, structural and magnetic properties of BiSe thin films produced by CBD on different substrates for optoelectronics applications(Iop Publishing Ltd, 2019) Aydin, Fatih; Tezel, Fatma Meydaneri; Kariper, I. AfsinBiSe thin films have been grown on substrates as PMMA, ITO, glass and Si wafer by using chemical bath deposition (CBD) method. Deposition temperature and time and pH are kept to be constant during the production of the thin films. The thickness of BiSe thin films, which are produced on ITO, glass, PMMA and Si wafer substrate are 513, 468, 1039 and 260 nm, respectively. According to GAXRD results, the films, which are grown on glass and PMMA substrate, have amorphous structure, but, the films, which are grown on ITO and Si wafer substrate, have peaks of Bi2Se3 crystal. Grain sizes, crystallization number per unit area and dislocation density for ITO and Si wafer substrate are calculated as 112.40 nm and 43.04 nm; 2.25 x 10(-5) and 7.91 x 10(-5) (1/nm(2)); 40.11 x 10(-5) (1/nm(2)) and 53.96 x 10(-5) (1/nm(2)), respectively. The contact angles and critical surface tension of distilled water, ethylene glycol, formamide and diiodamethane liquids for thin films grown on glass, ITO, PMMA and Si wafers were obtained by the Zisman method. The % transmittance and % reflectance values of thin films grown on glass, ITO, PMMA are calculated as % T: 79.90, 92.76 and 67.37; % R: 6.18, 2.07 and 10.59, respectively. Eg values of thin films grown on glass, ITO, PMMA are calculated as Eg = 1.92; 2.18; 1.60 eV. The extinction coefficients, refractive indexes and relative dielectric constants of thin films grown on glass, ITO, PMMA are calculated as k = 0.007; 0.002 and 0.012; n = 1.65; 1.34 and 1.96; epsilon(1) = 0.271; 0.083 and 0.528 respectively. Sheet resistance, hall mobility, sheet carrier densities, bulk carrier densities and conductivity types for glass, ITO, PMMA and Si are 6.52 x 10(7), 6.65 x 10(1), 1.09 x 10(8) and 6.45 x 10(2) (Omega/cm(2)); 2.38, 1.21 x 10(-1), 5.34 and 1.52 (cm(2)/V.s); 4.01 x 10(10), 7.71 x 10(17), 1.06 x 10(10) and 6.34 x 10(15) (cm(-2)); 4.58 x 10(14), 1.50 x 10(22), 1.02 x 10(14) and 2.89 x 10(20) (cm(-3)); p, n, p and p, respectively. In addition, I-V characteristics and changes of magnetoresistance values versus magnetic field of the thin films are obtained by Van der Pauw method and HEMS.Öğe Production and applications of flexible/wearable triboelectric nanogenerator (TENGS)(Elsevier Science Sa, 2021) Korkmaz, Satiye; Kariper, I. AfsinTextile-based devices have attracted great attention in wearable electronics with their light weight, small size, wearability and excellent flexibility. Moreover, designing such devices properly is as important as their functionality. Wearable devices have to supply the power by themselves, which raised interest for the studies in this area. In this context, the devices known as triboelectric nanogenerators (TENG), which have a simple operating mechanism and easy design, and which convert biomechanical energy into electrical energy, are considered as the new generation energy harvesting technology. This study defines the TENG model using Maxwell's displacement current and it includes the discussions on recent studies, as well as the factors affecting TENG's efficiency. In addition to the literature review, new suggestions are also submitted for the researchers.Öğe The production of rGO/RuO2 aerogel supercapacitor and analysis of its electrochemical performances(Elsevier Sci Ltd, 2021) Korkmaz, Satiye; Kariper, I. Afsin; Karaman, Onur; Karaman, CerenIn this study, ruthenium was bonded to the reduced graphene oxide in an ultrasonic bath. The aerogel of the mixture was produced at -78 degrees C. Structural characterization of aerogels was done with XRD and FTIR, surface characterization was performed with STEM, and elemental analysis was conducted by EDX analysis. The produced aerogel composites were transformed into electrodes on conductive Nickel foam. IviumStat, a potentiostat/galvanostat device, was used for the electrochemical characterization of the symmetrical supercapacitors. According to CV voltammograms, rGO/RuO2 aerogels' highest specific capacitance was calculated as 328.6 F g-1 at a potential scan rate of 5 mV s-1. The assembled rGO/RuO2 aerogel-based supercapacitor cell offered a high energy density value of 31.1 W h kg-1 even at the power density of 8.365 kW kg-1; this is comparable to that of lead-acid and nickel-metal hybrid batteries.Öğe Pyroelectric nanogenerators (PyNGs) in converting thermal energy into electrical energy: Fundamentals and current status(Elsevier, 2021) Korkmaz, Satiye; Kariper, I. AfsinNowadays, getting energy from natural resources has become an area of interest for researchers with the increasing demand for renewable energy sources. Like triboelectric (TENG) and piezoelectric nanogenerators (PENG), which generate electrical energy from mechanical energy, pyroelectric nanogenerators (PyNG) can also convert the waste heat in the environment into electrical energy through pyroelectric materials. Especially with the integration of PyNG into wearable electronics, the wasted heat in the environment can easily and effortlessly be made ready for use. Besides, PyNGs can be integrated into masks that have become an indispensable part of our lives with the Covid-19 pandemic, which has become a global health problem today and affected the whole world. Wearable electronics' energy requirement can be met by converting waste heat into electrical energy without any extra effort. In this paper, the theory of the pyroelectric effect, pyroelectric materials, and the structure of PyNGs, and the latest developments in micro/nanoscale devices are presented; efficient materials and future challenges opportunities are discussed.Öğe Radioactive rays shielding film: coating on amorphous glass(Springer, 2020) Kariper, I. Afsin; Meydaneri Tezel, Fatma; Usta, MetinIn this study, boron and lead compounds were coated on amorphous glass. Chemical bath deposition method was used for coating. Films were produced in the baths with pH: 9-12. Some of the produced films were directly analyzed, whereas some of them were analyzed after annealing at 500 degrees C. The characterization of the films was performed by XRD, while surface characterization was performed by SEM and EDX analysis. The study was finalized by performing radioactive analyzes of the films. Am-241 isotopes were used as the radioactive source for Alpha rays, Co-60 for Gamma rays and Sr-90 for Beta rays. According to the results, it was found that the films produced at pH: 9-10 had low optical transmittance but were able to absorb alpha and beta particles considerably. However, despite the high optical permeability of the films produced at pH: 11-12, their absorption of radioactive particles was found to be lower than the others. As a result, it was found that the absorption characteristics of the films produced at baths with different pH depend on the relative rate of boron and lead elements found on the surface.
