Production of symmetric and asymmetric supercapacitorsfrom graphene based nanostructures

Günümüzde, enerji tüketiminin giderek artması, enerjinin üretiminin yanında depolanması sorunlarını da beraberinde getirmektedir. Enerji depolama sistemlerinde kullanılan elektroaktif malzemelerin farklı özellikteki maddelerin sentezi ve çeşitli cihazlarla karekterizasyonu sonucu elde edilen veriler birçok araştırmacıya ışık olmaktadır. Bu doktora tezinde rGO/TiO2 , rGO/Co3 iv O4 gibi ikili ve rGO/TiO2 /PANI ve rGO/Co3 O4 /PPy gibi üçlü nanokompozitlerin sentezleri gerçekleştirilmiş olup, ayrıca kendi içlerinde farklı oranlardaki ([rGO]o /[TiO2 ]o =1:1, 1:2, 1:5, 1:10, [rGO]o /[TiO2 ]o /[ANI]o = 1:5:1, 1:5:2, 1:5:3, 1:5:4 ve 1:5:5, [rGO]o /[Co3 O4 ]o = 1:1, 1:2, 1:5, 1:10 ve rGO]o /[Co3 O4 ]o /[Py]o = 1:5:1, 1:5:2, 1:5:5 ve 1:5:10) nanokompozitlerin sentezleri de tamamlanmıştır. Sentezi tamamlanan nanokompozitlerin BET yüzey alanı, FTIR-ATR, TGA-DTA, XPS, SEM-EDX, TEM, XRD, Raman ve katı iletkenlik gibi çeşitli cihazlarla karakterizasyon işlemleri gerçekleştirilerek gerekli grafik ve çizelgeler oluşturulmuştur. Ayrıca nanokompozitlerin elektrokimyasal performans testleri öncesi elektroaktif malzemeler pelet, çamur gibi iki farklı yöntem kullanılarak elektrotlara birleştirilmiştir. Nanokompozit aktif malzemeler, paslanmaz çelik elektrotlarda ve düğme pil elektrotları (bakır ve alüminyum folyo) gibi farklı elektrot malzemelerinin de süperkapasitörlere olan katkısı incelenmiştir. Ayrıca süperkapasitör cihaz tasarımı olarak simetrik ve bir adet asimetrik düğme pil süperkapasitör cihaz elde edilmiştir. Elde edilen farklı oranlardaki rGO/TiO2 ve rGO/TiO2 /PANI nanokompozitleri 1M H2 SO4 elektrolitinde, rGO/Co3 O4 nanokompozitleri 3M KOH, rGO/Co3 O4 /PPy nanokompozitleri ise hem 2M KOH hem de 6M KOH elektrolitinde ve rGO/Co3 O4 /PPy//rGO/CuO nanokompozitleri iyonik sıvı elektrolitinde elektrokimyasal testleri (EIS, DV, GCD, ve DV’den elde edilen döngü kararlılığı performansları) başarıyla tamamlanmıştır. Nanokompozitlerin elektrokimyasal test sonuçlarından enerji ve güç yoğunluğu ve spesifik kapasitans grafikleri oluşturulmuştur. Ayrıca, ikili ve üçlü nanokompozitlerde metal oksit oranının arttırılmasının etkisi ve iletken polimer oranının arttırılmasının süperkapasitör cihaz performansı parametrelerine etkisi incelenmiştir. Nanokompozitlerin diğer parametreleri (farklı elektrot hazırlama teknikleri, elektrolit, düğme pil, paslanmaz çelik elektrot, simetrik ve asimetrik cihaz tasarımı vb.) incelenerek elde edilen veriler yorumlanmış süperkapasitör üretiminde araştırmacılara da önemli oranda katkı sağlanmıştır.Today, the gradual increase in energy consumption brings along the problems of energy storage as well as production. The data obtained as a result of the synthesis of substances with different properties and the characterization of the electroactive materials used in energy storage systems with various devices are a light for many researchers. In this doctoral thesis, the syntheses of binary nanocomposites such as rGO/TiO2 , rGO/Co3 O4 and ternary nanocomposites such as rGO/TiO2 vi /PANI and rGO/Co3 O4 /PPy were carried out, and also in different ratios ([rGO]o /[TiO2 ]o =1:1). , 1:2, 1:5, 1:10, [rGO]o /[TiO2 ]o /[ANI]o = 1:5:1, 1:5:2, 1:5:3, 1:5: 4 and 1:5:5, [rGO]o /[Co3 O4 ]o = 1:1, 1:2, 1:5, 1:10 and rGO]o /[Co3 O4 ]o /[Py]o = 1: 5:1, 1:5:2, 1:5:5 and 1:5:10) syntheses were performed. The necessary graphs and charts were created by performing the characterization processes of the synthesized nanocomposites with various devices such as BET surface area, FTIR-ATR, TGA-DTA, XPS, SEM-EDX, TEM, XRD, Raman and solid conductivity. In addition, before electrochemical performance tests of nanocomposites, electroactive materials were combined with electrodes using two different methods such as pellets and mud. The contribution of different electrode materials such as nanocomposite active materials, stainless steel electrodes and button cell electrodes (copper and aluminum foil) to supercapacitors has been investigated. In addition, as the supercapacitor device design, a symmetric and one asymmetric button cell supercapacitor device was obtained. Different ratios of rGO/TiO2 and rGO/TiO2 /PANI nanocomposites obtained in 1M H2 SO4 electrolyte, rGO/Co3 O4 nanocomposites in 3M KOH, rGO/Co3 O4 /PPy nanocomposites in both 2M KOH and 6M KOH electrolytes and rGO/Co3 O4 /PPy//CuO nanocomposites in ionic liquid electrolyte electrochemical tests (cycle stability performances from EIS, DV, GCD, and DV) of have been successfully completed. Energy and power density and capacitance graphs were created from the electrochemical test results of nanocomposites. In addition, the effect of increasing the metal oxide ratio in binary and triple nanocomposites and the effect of increasing the conductive polymer ratio on the supercapacitor device performance parameters were investigated. The data obtained by examining other parameters of nanocomposites (different electrode preparation techniques, electrolyte, button cell, stainless steel electrode, symmetric and asymmetric device design, etc.) have been interpreted and a significant contribution has been made to the researchers in the production of supercapacitors

The appointment of some trace elements in the sunflower (Helianthus annuus L.) growth on the Cacthment Area of Ergene with ICP-OES

Bu çalışma, Ergene Havzasında yetiştirilen ayçiçek bitkisinde (Helianthus annuus L.) ve bitkinin yetiştiği topraklarda copper, iron, manganese, zinc, lead ve cadmium içeriklerinin incelenmesi amacıyla planlanmıştır. Ergene Havzasındaki kirlenmeyi, inorganik çevre kirliliği parametreleri arasında ilk sırayı alan eser elementler açısından belirleyebilmek için, temsili örnekler mümkün olduğunca karasteristik bölgelerden seçildi. Bu amaçla 5 ana istasyona bağlı 24 istasyondan 72 adet çevre örneği (bitki, toprak) alındı. Örneklemede, paralel örnekler alınarak hatanın en aza indirgenmesine çalışıldı. Örnekleme, ayçiçeğin baş kısmı, ayçiçeğin kökü, ayçiçeğin çıkarıldığı yerden alınan toprak örnekleri şeklinde gerçekleştirildi. Alınan örnekler 60 CO'de etüvde 48 saat bekletildi. Kurutma işleminden sonra öğütülerek hem homojen bir şekilde karışması hem de çözünürleştirme işlemleri için hazır hale getirilmesi sağlandı. Hazırlanan örneklerden 0,25'er gram alınarak, ayçiçek ve kök örnekleri derişik HCl-derişik HNO3 karışımı ile toprak örnekleri ise derişik HNO3?derişik H2O2 karışımı ile mikrodalga çözünürleştirme sistemi ile çözünürleştirildi. Örneklerin eser element ölçümleri Perkin Elmer 5300DV model İndüktif Eşleşmiş Plazma Optik Emisyon Spektrofotometresiyle (ICP-OES) yapıldı. Çalışmamızdan elde edilen sonuçlara göre toprak örneklerinin metal konsantrasyonları Toprak Kirliliği Kontrol Yönetmeliği'nce belirlenen sınırların altında bulundu. Sadece kadmiyum (Cd) değerleri bu sınırların üzerinde tayin edilerek ?toksik? olarak nitelendirildi. Bitki örneklerinde ise, köklerdeki metal konsantrasyonları (Cu ve Mn hariç), ayçiçek(baş+çekirdek) örneklerindeki metal konsantrasyonlarından daha yüksek bulundu. Bu da köklerde depolanan elementlerin aynı yoğunlukta ürün kısmına geçmediğini göstermektedir. Metal depolayan türler arasında yer alan ayçiçek bitkisinin (Helianthus annuus L.) incelenen elementleri, çalışılan bölgedeki çeşitli parametrelere bağlı olarak biriktirdiği gözlendi.In this study, the concentrations of copper, iron, manganese, zinc, lead and cadmium in soil and sunflower (Helianthus annuus L.) plant from Ergene field have been investigated. This study concerns the problem of trace elements in the environment, especially in soil and plant samples. Sunflower samples were taken from five locations. In total, 72 samples from 24 sampling points, including soil, sunflower roots and sunflower head parts. Samples were dried at 60 oC for 48 hours. The dried samples were ground and homogenized. For digestion of the samples, 0,25 gram samples were digested with concentrated HCl-concentrated HNO3 mixture for plant parts and concentrated HNO3- concentrated H2O2 mixture for soil in microwave digestion system. In the final solutions, the concentrations of trace elements for soil and plant samples were determined by Perkin Elmer 5300DV model, Inductively Coupled Plasma Emission Spectroscopy (ICP-OES). In this study, the concentrations of trace elements in soil samples were observed under the limits of Soil Contamination Control Administration. Only concentration of cadmium were found above this limits and described as a ?toxic?. The concentration of trace elements in sunflower roots, except for copper and manganese concentrations were higher than in sunflower (heat + seed) samples. The results obtained in these experiments shows that the investigated elements are being accumulated by metal accumulating plants, such as sunflower

Symmetric supercapacitor device applications of rGO / Co3O4 / polypyrrole nanocomposites

Symmetric supercapacitor electrode design and synthesis of micro-nano structured metal oxide (Co3O4) and polypyrrole with reduced graphene oxide (rGO) have played an important role in supercapacitor investigations. The characterizations of rGO/Co3O4/PPy nanocomposites were given by FTIR-ATR, SEM-EDX, TGA-DTA, BET surface, and porous analysis and Four-point probe analysis. The symmetric rGO/Co3O4/PPy supercapacitor devices were presented in different initial feed ratios of [rGO](o)/[Co3O4](o)/[Py](o) = 1:5:1; 1:5:2; 1:5:5 and 1:5:10 for 2 M and 6 M KOH solutions. The highest specific capacitances, energy and power densities of C-sp = 896 F x g(-1), E = 31.75 Wh x kg(-1) and P = 11,705 W x kg(-1) for [rGO](o)/[Co3O4](o)/[Py](o) = 1:5:10 in 2 M KOH solution and C-sp = 1370 F x g(-1) for [rGO](o)/[Co3O4](o)/[Py](o) = 1:5:5 and E = 31.43 Wh x kg(-1) and P = 11,600 W x kg(-1) for [rGO](o)/[Co3O4](o)/[Py](o) = 1:5:1 in 6 M KOH solution. The lowest capacitance retention was obtained as 3.69% in 2 M KOH solution for [rGO](o)/[Co3O4](o)/[Py](o) = 1:5:1 after 1000 cycle charge/discharge performances by CV method. Symmetric supercapacitor of rGO/Co3O4/PPy should open up new opportunities for the next-generation high-performance supercapacitors.TUBAP [2018-138]We would like to thank TUBAP (project no:2018-138), TUTAGEM (Trakya Uni., Edirne, Turkey) for purchasing FTIR-ATR and SEM-EDX. We also thank DAYTAM (Ataturk Uni., Erzurum, Turkey) for conducting measurements for TEM analysis

Design and assembly of supercapacitor based on reduced graphene oxide/TiO2/polyaniline ternary nanocomposite and its application in electrical circuit

Supercapacitor devices are used as energy storage technology for electrical circuits. Graphene, metal oxide, and conducting polymers are used as electroactive materials to enhance energy, power density, and cycle life. The present study uses TiO2 and rGO materials, which are added to polyaniline (PANI). The nanocomposite structure can be observed using different initial feed ratios of rGO, TiO2, and aniline monomer as [rGO]o/[TiO2]o/[ANI]o = 1:5:1, 1:5:2, 1:5:3, 1:5:4, and 1:5:5. Fourier transform infrared–attenuation–transmission reflectance, scanning electron microscopy–energy-dispersive X-ray analysis, Brunauer–Emmett–Teller surface area, thermal-gravimetric analysis (TGA-DTA), X-ray diffraction (XRD), Raman spectroscopy, X-ray photon spectroscopy, and transmission electron microscopy analysis are conducted. Electrochemical performances of a ternary nanocomposite material are carried out by cyclic voltammetry, galvanostatic charge–discharge measurements, and electrochemical impedance spectroscopy (EIS). According to results, rGO/TiO2/PANI nanocomposite shows much better performance than its individual components in terms of specific capacitance, energy density, power density, and cycle life. The highest specific capacitance is obtained as Csp = 692.87 F/g at 2 mV/s for [rGO]o/[TiO2]o/[ANI]o = 1:5:4. A new real circuit model of LRs(CR1)(QR2) is adopted to our device, which supplies enough energy to the light LED lamp (1.8 V) for 3 min. As a result, rGO/TiO2/PANI nanocomposite may be used as a promote candidate for energy storage systems. Graphic abstract: [Figure not available: see fulltext.]. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature

Supercapacitor performances of RuO2/MWCNT, RuO2/Fullerene nanocomposites

In this study, RuO2/Fullerene and RuO2/MWCNT nanocomposites were synthesized to use as an electroactive materials in symmetric supercapacitor device performances. The materials were examined via Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), thermo-gravimetric analysis (TGA-DTA), scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The RuO2/MWCNT and RuO2/Fullerene nanocomposite electrodes show good electrochemical performances. For instance, the highest specific capacitance of RuO2/Fullerene and RuO2/MWCNT electrodes reaches C-sp = 3895.11 and 1662.19F/g at 1mV/s within the potential range of 0.8 V in 1 M H2SO4 solution. RuO2/MWCNT and RuO2/Fullerene nanocomposites have good cycle stability similar to 100% specific capacitance at [RuO2](o)/[MWCNT](o) = 1:1; 2:1 and [RuO2](o)/[Fullerene](o) = 2:1, respectively. The different equivalent circuit models of LR(1)Q(C1R2) and LR1(Q(1)R(2))(Q(2)R(3)) were used to interpret EIS data

Synthesis of RGO/TiO2/PEDOT Nanocomposites, Supercapacitor Device Performances and Equivalent Electrical Circuit Models

A new nanocomposite electrode incorporating poly(3,4-ethylenedioxythiophene) (PEDOT) within the nanocomposite film of the reduced graphene oxide / Titanium dioxide (TiO2) was synthesized to be used in supercapacitor devices. We used constant EDOT monomer for in-situ polymerization and different initial monomer concentration ratio of [rGO]o/[TiO2]o = 1/1, ½ and 1/5. The obtained nanocomposites were examined by FTIR-ATR, UV-vis, SEM-EDX, TGA-DTA, BET surface areas and pore distribution, XRD, TEM, AFM, CV, GCD and EIS analyses. The results showed that graphene oxide was successfully reduced to rGO by means of the microwave-assisted method. It was confirmed by the increases in the specific capacitance of (Csp = 652 F/g) at 1 mV/s for the rGO/TiO2/PEDOT nanocomposite at [rGO]o/[TiO2]o = 1/5. This was related to the pore size (~33.50 nm) of the material for rGO/TiO2/PEDOT at [rGO]o/[TiO2]o = 1/5 obtained from BET analysis. The other Csp values were 475.33 F/g for [rGO]o/[TiO2]o = 1/2, 114.09 F/g for rGO/PEDOT and 48.02 F/g for [rGO]o/[TiO2]o = 1/1. Equivalent circuit model of Rct(CdlRct) was analyzed via ZSimpWin and TINA programmes. A facile and inexpensive approach for a ternary nanocomposite synthesis of rGO/TiO2/PEDOT was presented for future supercapacitor applications