1,721,005 research outputs found
Synthesis of new carbon material produced from human hair and its evaluation as electrochemical supercapacitor
No full textAslan, Sema/0000-0001-9796-7311In this study, carbon material similar to graphene structure (GLS) was prepared from graphite and the carbonization of Turkish human hair fibers (HHC) and utilized for the modification of electrode to evaluate the supercapacitance performance. Electrochemical characterization of the HHC-based GLS (HHC-GLS) modified electrodes have been carried out with cyclic voltammetry and electrochemical impedance spectroscopy. the morphology and chemical composition of the resultant GLSs were characterized by scanning electron microscopy, X-Ray diffraction spectroscopy, Raman and Fourier Transform infrared spectroscopy analysis. HHC-GLS displayed a good electrochemical activity than the graphite sourced graphene and possess very similar morphological properties with commercial graphene. Carbonization of the waste hair was carried out at 280 degrees C to improve the pore structure as the first step of GLS synthesis. HHC-GLS modified electrode exhibited the best electrochemical activity and utilized as a charge storage device. the best specific capacitance value was found to be 139.00 F g(-1)in 6.00 M KOH((aq))at a scan rate of 100.00 mV s(-1)and good stability over 500 cycles. Whereas an energy density of 19.3 Wh kg(-1)and power density of 6.95 kW kg(-1)were obtained from the electrode when operated in the voltage range from -1.00 to 0.00 V. This work offers a new approach to human hair waste management in terms of promising green energy applications. This study was patented by the Turkish Patent and Trademark Office (Turkish Patent Institute Application Number: (2019/22841))
Evaluation of the fuel cell performances of TiO2/PAN electrospun carbon-based electrodes
No full textElectrocatalytic effect of the untreated and TiO2+polyacrylonitrile (PAN) modified discarded battery coal (DBC) and pencil graphite electrodes (PGE) were evaluated in fuel cell (FC) applications. TiO2 + PAN solution is coated on PGE and DBC electrodes by electrospinning. According to the FESEM and EDS characterizations, TiO2 and PAN nanofibers are found to be approximately 40 and 240 nm in size. TiO2+PAN/PGE showed the best FC performances with 2.00 A cm(-2) current density and 5.05 W cm(-2) power density values, whereas TiO2+PAN/DBC showed 0.68 A cm(-2) current density and 0.62 W cm(-2) power density values. Electrochemical characterizations of PGE and TiO2+PAN/PGE electrodes were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Finally, long-term IV measurement results of developed electrodes exhibited very reasonable recovery values. Along with the comparison of the electrode performances, the recovery of DBCs as electrodes for renewable energy production has been achieved
An electrochemical immunosensor modified with titanium IV oxide/polyacrylonitrile nanofibers for the determination of a carcinoembryonic antigen
No full textCarcinoembryonic antigen (CEA) is considerably addressed for the clinical diagnosis of miscellaneous tumor types. In this study, an electrochemical immunosensor for the determination of the CEA biomarker was presented. Titanium(iv) oxide nanoparticle (TiO2np)-loaded polyacrylonitrile nanofibers (PANnf) were prepared by electrospinning at the surface of the discharged battery coal electrode (DBC), and loaded with CEA antibodies (Anti-CEA) as the CEA biomarker receptor. Finally, DBC/PANnf + TiO2np/Anti-CEA was utilized for the CEA detection. Fabrication steps were characterized by cyclic voltammetry and electrochemical impedance spectroscopy in the presence of a [Fe(CN)6]3−/4−probe. Results demonstrated that PANnf and TiO2nps exhibited a very fine network for immunosensing. The usage of this composite system is a novel immunosensor development approach for the label-free detection of CEA. Under optimal conditions, the DBC/PANnf + TiO2np/Anti-CEA immunosensor exhibited high sensitivity toward the CEA biomarker in the low concentration range of 0.01-10 ng mL−1, with the detection limit of 0.01 ng mL−1and relative standard deviation of 1.17 (n= 5). Results indicated that even very small changes in the CEA concentration can be sensed with the presented system. Also, the recovery of the immunosensor was found to be 99.42% ± 1.41 in real sera samples containing dopamine and ascorbic acid. It has great potential in the clinical screening of divergent cancer biomarkers. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021The author acknowledges to Assoc. Prof. Derya Bal Altuntas-, Dr Ça˘gdas-Koçak, and Prof. Hülya Kara Subas-at for their contribution, and financial support and scholarships from TUBITAK (The Scientific and Technological Research Council of Turkey) with the project number of 218M223
Microbial glucose biosensors based on glassy carbon paste electrodes modified with Gluconobacter Oxydans and graphene oxide or graphene-platinum hybrid nanoparticles
No full textWOS: 000367692900007We have performed a study on the performance of two microbial glucose sensors based on immobilized Gluconobacter oxydans (G. oxydans). The first one was prepared by modifying a glassy carbon paste electrode (GCPE) containing the microbial cells with graphene oxide (GO), the other one by modifying it with graphene-platinum hybrid nanoparticles (graphene-Pt NPs). The electrode was characterized by following the voltammetric signals of the oxidation of hexacyanoferrate(II) to hexacyanoferrate(III) via the oxidative enzymes contained in G. oxydans which convert glucose to gluconic acid. Optimizations were conducted with a conventional GCPE containing G. oxydans. After material optimization, the biosensors were applied to the determination of glucose. The linear and analytical ranges for GO based biosensor range from 1 to 75 mu M (linear) and 1 to 100 mu M (analytical), respectively, with a limit of detection (LOD) of (3 s/m) 1.06 mu M (at an S/m of 3). On the other hand, the graphene-Pt hybrid nanoparticle based biosensor showed two linear ranges (from 0.3 to 1 A mu M and from 1 to 10 mu M), a full analytical range from 1 to 50 mu M, and an LOD of 0.015 mu M. The graphene-Pt hybrid NP based sensors performs better and was applied to the determination of glucose in synthetically prepared plasma samples where it gave recoveries as 101.8 and 104.37 % for two different concentrations. Selectivity studies concerning fructose, galactose, L-ascorbic acid and dopamine were also conducted.Mugla Sitki Kocman University BAP ProjectMugla Sitki Kocman University [13 / 17]The grant from Mugla Sitki Kocman University BAP Project number 13 / 17 is greatly acknowledged
Electrochemical Carbon Dioxide Detection
No full textIn this chapter, initially, the concerns about global warming and greenhouse effects, and the research on sensing, capturing, and monitoring carbon dioxide (CO2) have been discussed in a general manner. After that, the fundamental methods and electrodes used in the electrochemical measurements are given. Finally, the electrochemical detection and reduction of CO2 are detailed by potentiometric, amperometric, conductometric, voltametric, or coulometric sensors that can be utilized easily as directly as solid-state or electrolyte using types. The electrodes used as well as the measurement methods increase the variety of these sensors. From the Clark electrode to the present, Field Effect Transistors, Kelvin probes, oxygen probes, electronic noses, solid electrodes which are reinforced by using divergent nanomaterials, transition metal oxides, polymers, and porous solid electrodes were utilized in different gas sensing electrochemical method
NaOH impregnated sepiolite based heterogeneous catalyst and its utilization for the production of biodiesel from canola oil
No full textWOS: 000452483700004NaOH/sepiolite nanocomposite heterogenous base catalyst (NaOH/sep.) was prepared via impregnation process and tested in a three-neck flask equipped with thermometer and reflux condenser for the production of biodiesel from transesterification of canola oil in an excess amount of methanol. The ratio of NaOH and sepiolite was selected as 1:4. The influence of various operational parameters was examined such as methanol to oil molar ratio, catalyst dosage, and reaction temperature. Untreated sepiolite and NaOH loaded sepiolite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy and Energy dispersive spectroscopy analysis. Overall NaOH/sep. based biodiesel production yield was examined by the help of Gas chromatography-mass spectrometry analysis. The yield was calculated from the peak areas as 80.93% which is better than that of expensive catalysis system using studies.Mugla Sitki Kocman UniversityMugla Sitki Kocman University [15/125]Mugla Sitki Kocman University is greatly acknowledged for the grant from BAP Project number 15/125
PREPARATION AND APPLICATION OF KOH IMPREGNATED SEPIOLITE AS A SOLID BASE CATALYST FOR BIODIESEL PRODUCTION USING MICROWAVE IRRADIATION
No full textAn active basic solid catalyst for biodiesel production was obtained via KOH impregnation onto sepiolite support followed by high temperature calcination. The transesterification of rapeseed oil over the resulting nanocomposite structure was investigated using a microwave reactor. Morphological and structural characterization of sepiolite and KOH impregnated sepiolite was carried out by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis. Optimization of the operational parameters such as methanol to oil molar ratio, catalyst loading, reaction temperature and reaction time were examined. Reusability of the catalyst and the reactions utilizing waste cooking oil were also studied. Obtained results indicated that the basic heterogenous catalysis diminishes the saponification during the transesterification reaction and that microwave heating was very effective at shortening the biodiesel production time. However, the reusability of the KOH impregnated sepiolite catalysts and their structural stability require further investigation
Fabrication of Biofuel Cell Based on Nanomaterial Modified Composite Glassy Carbon Paste Electrode
No full textWOS: 000362586800006In this work, an enzymatic biofuel cell (BFC) was developed by combining nanomaterial modified and plain glassy carbon paste electrodes (GCPE). Because of the composite nature of GCPE, very practical and economic bio-anode and bio-cathode electrodes were formed. Bio-anode electrode was obtained by modification of composite GCPE with glucose oxidase (GOx) and gold nanoparticle (Au np). The effects of various nanomaterials like, aluminum titanate, manganese (IV) oxide nanoparticle and Fe3O4-Au bimetallic nanostructure on GCPE performance were also searched. p-benzoquinone mediator was used for the electron transfer between enzyme redox center and bio-anode electrode where glucose analyte was used as substrate. Optimization of experimental parameters (e.g. substrate concentration, mediator concentration, enzyme amount, temperature and pH) of bio-anode were carried out by linear sweep volt-ammetry. Laccase (Lac) modified plain GCPE was used as bio-cathode electrode. Then Au np modified GCPE and Lac modified GCPE were combined in a single cell and membraneless biofuel cell was obtained. The power density of single cell BFC was found as 6.7 mu W cm(-2) at a cell potential of 92 mV and current density of this system was obtained as 154.8 mu A cm(-2) in phosphate buffer solution
Electrochemical Properties of Coumarin 500 Encapsulated in a Liquid Crystal Guided Electrospun Fiber Core and Their Supercapacitor Application
No full textHere, we first report a study on coumarin 500 and liquid crystal including polyacrylonitrile nanofibers in terms of synthesis, characterizations, and supercapacitor performances. SEM, POM, FTIR, and DSC measurements showed that liquid crystal was inserted into the fine polyacrylonitrile nanofibers successfully. Because a strong molecular interaction took place between coumarin 500 and liquid crystal and coumarin 500 was sensitive to the polarity of the medium, the liquid crystal behaved as a guide material for coumarin 500, and it was expected that coumarin 500 was oriented by the director of the liquid crystal along the core of the fiber. The average polyacrylonitrile nanofiber size was between 0.19 to 0.25 mu m, and liquid-crystal-doped and liquid-crystal +coumarin-500-doped fibers exhibited a similar distribution, which is approximately in the 0.30 to 0.60 mu m interval. This proved that the fibers maintained their structure after modifications. Electrochemical evaluation of the different composite nanofibers showed that there was not a significant current increase upon liquid crystal addition into polyacrylonitrile nanofibers at voltammograms. C-s values were enhanced after the coumarin 500 addition into liquid-crystal-doped nanofiber and obtained as 410.60 F/g with a specific energy value of 57.03 Wh/kg. Additionally, the long-term charge-discharge test of the liquid-crystal+coumarin-500-doped polyacrylonitrile graphite electrode showed a very steady distribution between 100th and the 2500th cycles with a 14.12% Cs deviation. This is attributed to the stable and robust network of the PAN nanofiber and the synergetic effect between liquid crystal and coumarin 500 in the nanofiber net
Combination of a poly(3,4-ethylene-dioxythiophene) electrode in the presence of sodium dodecyl sulfate with centri-voltammetry
No full textWOS: 000359360400037A poly(3,4-ethylene-dioxythiophene) (PEDOT) electrode was prepared by electropolymerization of 3,4-ethylene-dioxythiophene (EDOT) in the presence of sodium dodecyl sulfate (SDS). The electrode was combined with centri-voltammetry for the first time and applied for dopamine (DA) detection. Under the experimental conditions, SDS provides a high density of negative charges to the PEDOT electrode and by this way the electrode attracts the positively charged DA. Also by applying centrifugation, effective accumulation of DA onto the electrode surface was achieved. Two linear ranges 1 x 10(-9) M to 1 x 10(-5) M and 2 x 10(-5) M to 1 x 10(-1) M with two LOD values of 5.9 nM and 3.1 nM were found for the developed system. Sample application and interference study were also conducted
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