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Öğe Different Plant Sporopollenin Exine Capsules and Their Multifunctional Usage(American Chemical Society, 2022) Atalay, Funda Ersoy; Culum, Ayşe Asiye; Kaya, Harun; Göktürk, Günay; Yiğit, Emelporopollenin exine capsules (SECs) are highly resistant to heat and various acids and bases. They are also cheap, highly porous, eco-friendly polymer biomaterials with stable microencapsulation capacity. Due to their strong and uniquely shaped exine layers, they can allow growth on metal oxide materials, as a biotemplate for use in different applications. In this study, first, a single SEC extraction method was applied to three different pollens from Pinus, Fraxinus excelsior, and Tilia. Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, and thermogravimetric/differential thermal analysis (TGA/DTA) measurements both before and after the extraction process were performed to observe changes in surface area, morphology, porous structure, and degradation properties. The protein content and removal were analyzed by elemental and spectrophotometric analyses. Then, SECs were loaded by passive and centrifuge loading for drug delivery, and the loading capacities were analyzed by Fourier transform infrared spectroscopy and spectrophotometry. The method was successful in opening the pores and maintaining the structural integrity of SECs. It was determined that the morphology and porosity affected the encapsulation efficiency. According to the loading capacities, Tilia SECs were the most efficient SECs for both loading methods. In addition, three different SECs were hydrothermally coated with cobalt and then heat-treated to obtain a metal oxide structure. A CO3O4supercapacitor electrode constructed using CO3O4-F. excelsior SEC powder had the best surface area parameters. The electrode showed a maximum specific capacity of 473 F/g for over 3000 continuous cycles of galvanostatic charge-discharge (GCD). © 2022 American Chemical Society. All rights reserved.Öğe Different Plant Sporopollenin Exine Capsules and Their Multifunctional Usage(American Chemical Society, 2022) Atalay Ersoy, Funda; Kaya, Harun; Göktürk, Günay; Yiğit, Emel; Çulum, Ayşe AsiyeSporopollenin exine capsules (SECs) are highly resistant to heat and various acids and bases. They are also cheap, highly porous, eco-friendly polymer biomaterials with stable microencapsulation capacity. Due to their strong and uniquely shaped exine layers, they can allow growth on metal oxide materials, as a biotemplate for use in different applications. In this study, first, a single SEC extraction method was applied to three different pollens from Pinus, Fraxinus excelsior, and Tilia. Scanning electron microscopy (SEM), Brunauer?Emmett?Teller (BET) analysis, and thermogravimetric/differential thermal analysis (TGA/DTA) measurements both before and after the extraction process were performed to observe changes in surface area, morphology, porous structure, and degradation properties. The protein content and removal were analyzed by elemental and spectrophotometric analyses. Then, SECs were loaded by passive and centrifuge loading for drug delivery, and the loading capacities were analyzed by Fourier transform infrared spectroscopy and spectrophotometry. The method was successful in opening the pores and maintaining the structural integrity of SECs. It was determined that the morphology and porosity affected the encapsulation efficiency. According to the loading capacities, Tilia SECs were the most efficient SECs for both loading methods. In addition, three different SECs were hydrothermally coated with cobalt and then heat-treated to obtain a metal oxide structure. A CO3O4 supercapacitor electrode constructed using CO3O4-F. excelsior SEC powder had the best surface area parameters. The electrode showed a maximum specific capacity of 473 F/g for over 3000 continuous cycles of galvanostatic charge?discharge (GCD).Öğe The formation of RuO2 structures on cladosporium cladosporioides hyphal and an investigation of their properties(Adıyaman Üniversitesi, 2018) Kaya, HarunIn this study, ruthenium oxide (RuO2) was grown on Cladosporium Cladosporioides hyphal using a chemical precipitation method. The morphological characteristics of the material obtained by chemical precipitation method were determined by Scanning Electron Microscope (SEM); its surface area by Brunauer-Emmett-Teller (BET) equipment and its electrochemical properties, such as charging–discharging, cyclic voltammetry (CV) and electrochemical impedance characteristics, using a Gamry 3000 potentiostat system.Öğe High- Performance Supercapacitor Electrode Based on NiFe Nanowire Networks/PEDOT:PSS(Elsevier Ltd, 2020) Ersoy Atalay, Funda; Şener, Melike; Kaya, HarunIn this work, the usage of electrochemically produced NiFe nanowires (NW) as an electrode active material for supercapacitors has been investigated. Different concentrations of NiFe NWs were dispersed on thin conductive poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) films by spin coating system. NiFe NW networks/PEDOT:PSS electrode was used as a positive electrode in the three-electrode cell. Electrochemical capacitive performance tests such as; electrochemical impedance spectroscopy, galvanostatic charge-discharge tests (GCD) and cyclic voltammetry (CV) were performed in 1 M Na2SO4 electrolyte. The CV curves of the designed electrodes have been found to be similar to the CV curves of the ideal supercapacitor and they have almost rectangular in shape. The specific capacitance of 2 mg NW mass loading was evaluated 332 F/g at a current density of 2 A/g from GCD measurements with excellent cyclability up to 5000 times. These good electrochemical performances arise from network structure of NiFe NW based electrodeÖğe Juglans Sporopollenin for high-performance supercapacitor electrode design(American Chemical Society, 2020) Atalay, Funda Ersoy; Bingöl, Alper; Kaya, Harun; Emre, Yıldız; Baş, Hatice Hande; Culum, Ayşe AsiyeRecently, plant pollen has been used as a source of activated carbon to produce carbon-containing supercapacitor electrodes. However, in this study, pollen was used as a biotemplate with a completely different approach. As a biotemplate, pollen offers a wide range of varieties in terms of exterior, porosity, shape, and size. An electrode formed by the use of metal oxide grown on the pollen exine layer (sporopollenin microcapsules) as the active substance will inevitably exhibit good electrochemical capacitive properties. Juglans male flowers have been distinguished by dissection from anthers. Isolation of pollen grains from anthers was carried out using sieving from suitable sieves (45-200 mu m). Juglans sporopollenin exine microcapsules (SECs) were separated from the intine and protoplasm by acetolysis in combination with reflux. The solution containing SECs, metal ions, and Ni foam was put into a Teflon-lined hydrothermal container, and then, it was reacted at 120 degrees C for 15 h. The resulting precipitate, as well as the Ni foam, was heat-treated at 300 and 360 degrees C for 3 h in air. The raw pollen, chemically treated pollen, and cobalt-coated SEC (CoSEC) and CoSEC/Ni foam were characterized using scanning electron microscopy, Brunauer-Emmett-Teller surface area analysis, thermogravimetric analysis, and X-ray diffraction techniques. Two different types of supercapacitor electrode designs, with the use of exine microcapsules of Juglans sporopollenin, were performed for the first time. The maximum specific capacitance was up to 1691 F g(-1) at 5 A g(-1).Öğe A Rapid Response Humidity Sensor for Monitoring Human Respiration with TiO2-Based Nanotubes as a Sensing Layer(The Minerals, Metals & Materials Society, 2020) Atalay, Selçuk; Erdemoğlu, Sema; Kolat, Veli Serkan; İzgi, Tekin; Akgeyik, Emrah; Çağlar Yılmaz, Hatice; Kaya, Harun; Ersoy Atalay, FundaThe use of TiO2-based samples with nanotube (NT) shape for humidity sensing has been investigated. Sample characterization was carried out using x-ray diffraction analysis, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy. x-Ray diffraction analysis showed that the nanotubes had TiO2, NaO3, and H2Ti2O5 phases. SEM revealed that the NTs had diameters ranging from 20 nm to 200 nm and very different lengths. TiO2-based nanotubes were coated using the drop-casting method onto a quartz crystal microbalance (QCM). The synthesis of TiO2-based NTs was performed using a hydrothermal process. Humidity sensing measurements showed that the resonant frequency of TiO2-based NTs deposited onto the QCM was very sensitive to humidity changes. It was also shown that the sensor could be used for respiratory monitoring purposes.Öğe Sol–gel synthesis of TiO2 on Co3O4-coated sporopollenin exine microcapsules (SECs) and photocatalytic performance of new semiconductor heterojunction material(Springer, 2022) Çağlar Yılmaz, Hatice; Ersoy Atalay, Funda; Kaya, Harun; Erdemoğlu, SemaIn this study, a new approach was developed to prepare mesoporous hybrid TiO2/Co3O4 coated on Juglans sporopollenin exine microcapsules (SECs). TiO2 was synthesized on Co3O4-coated SECs used as substrate, by sol–gel method. The obtained semiconductor/semiconductor hetero-junction hybrid materials were characterized with X-ray diffractometry (XRD), UV–Vis absorption spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), particle size distribution, specific surface area, and zeta potential measurements. Photocatalytic performances of hybrid materials were tested for Reactive Black 5 dye under both UV and visible light. Equilibrium pH of the solution containing 10 mg/L Reactive Black 5 dye and 0.1% wt/v TiO2/Co3O4 was around 4.7. After irradiation in the solar box, more than 98% of the Reactive Black 5 was photocatalytically degraded within 60 min.Öğe Synthesis of NiO/SnO2 nanowires for energy applications(Polska Akademia Nauk, 2020) Kaya, HarunIn this study, SnO2 nanowire arrays with lengths in the micrometres range were successfully synthesised by using polyethylene glycol (PEG) at room temperature. Then Ni was coated onto the SnO2 nanowires by chemical precipitation. These nanowires were heat-treated at 360, 450, 500, and 650 degrees C to form various phases. X-ray powder diffraction studies showed that the heat-treated sample at 500 degrees C has a tetragonal rutile SnO(2 )phase. The Brunauer-Emmett-Teller surface area of the untreated Sn(COO)(2) nanowires was determined as 5.74 m(2)/g. After Ni coating and heat treatment at 360, 450, 500, and 650 degrees C, the surface areas of the NiO/SnO2 nanowires were measured to be 79.75, 33.38, 29.15, and 21.13 m(2)/g, respectively.
