Recep Yuksel

Transparent and flexible supercapacitors with single walled carbon nanotube thin film electrodes.

We describe a simple process for the fabrication of transparent and flexible, solid-state supercapacitors. Symmetric electrodes made up of binder-free single walled carbon nanotube (SWCNT) thin films were deposited onto polydimethylsiloxane substrates by vacuum filtration followed by a stamping method, and solid-state supercapacitor devices were assembled using a gel electrolyte. An optical transmittance of 82% was found for 0.02 mg of SWCNTs, and a specific capacitance of 22.2 F/g was obtained. The power density can reach to 41.5 kW · kg(-1) and shows good capacity retention (94%) upon cycling over 500 times. Fabricated supercapacitors will be relevant for the realization of transparent and flexible devices with energy storage capabilities, displays and touch screens in particular.

A novel approach for the fabrication of a flexible glucose biosensor: The combination of vertically aligned CNTs and a conjugated polymer.

A novel flexible glucose biosensor using vertically aligned carbon nanotubes (VACNT) and a conjugated polymer (CP) was fabricated. A scaffold based on VACNT grown on aluminum foil (VACNT-Al foil) with poly (9,9-di-(2-ethylhexyl)-fluorenyl-2,7-diyl)-end capped with 2,5-diphenyl-1,2,4-oxadiazole (PFLO) was used as the immobilization matrix for the glucose biosensor. Glucose oxidase (GOx) was immobilized on a modified indium tin oxide (ITO) coated polyethylene terephthalate (PET) electrode surface. The biosensor response at a potential of -0.7V versus Ag wire was followed by the decrease in oxygen level as a result of enzymatic reaction. The biosensor exhibited a linear range between 0.02mM and 0.5mM glucose and kinetic parameters (KMapp, Imax, limit of detection (LOD) and sensitivity) were estimated as 0.193mM, 8.170μA, 7.035×10-3mM and 65.816μA/mMcm2, respectively. Scanning electron microscopy (SEM) was used for surface characterization. The constructed biosensor was applied to determine the glucose content in several beverages.

Manganese dioxide nanowires on carbon nanofiber frameworks for efficient electrochemical device electrodes

Hierarchically nanostructured composite electrodes were prepared by the electrodeposition of manganese dioxide nanowires (MnO2 NWs) with 5–20 nm diameters on electrospun carbon nanofiber (CNF) webs with diameters of 250 and 650 nm. The effects of CNF diameters and mass loading of MnO2 NWs on the hierarchical nanostructure formation and the performance of the composite electrodes were investigated. The internal structure of the composite electrode depended on CNF diameter and mass loading of MnO2 NW. The electrodes based on thinner CNFs and higher mass loadings of MnO2 NWs showed higher values of gravimetric and volumetric capacitances. This would be due to MnO2 NWs forming a dense network in the thinner three-dimensional CNF framework. In addition, asymmetric supercapacitors with the MnO2 NW/CNF composite electrode as the positive electrode and activated carbon as the negative electrode showed high energy and power densities of 8.9 W h kg−1 and 4.9 kW kg−1, respectively. These results clearly indicate that the hierarchical network nanostructure composed of an active material and a charge collector can be considered a promising electrode for various electrochemical devices.

Su Arıtımı İçin Etkili Bir Yöntem Olarak Kapasitif Deiyonizasyon Teknolojisinin Geliştirilmesi

1 Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Çevre Mühendisliği Bölümü, 06800, Ankara 2 Orta Doğu Teknik Üniversitesi, Fen Bilimleri Enstitüsü, Çevre Mühendisliği Bölümü, 06800, Ankara 3 Orta Doğu Teknik Üniversitesi, Fen Bilimleri Enstitüsü, Mikro ve Nanoteknoloji Bölümü, 06800, Ankara 4 Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Metalurji ve Malzeme Mühendisliği Bölümü, 06800, Ankara