Yazar "Sisman, Orhan" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim Yok
    Öğe
    AAO-Assisted Nanoporous Platinum Films for Hydrogen Sensor Application
    (Mdpi, 2023) Sener, Melike; Sisman, Orhan; Kilinc, Necmettin
    The effects of the porosity and the thickness on the ability of hydrogen sensing is demonstrated through a comparison of compact and nanoporous platinum film sensors. The synthesis of anodic aluminum oxide (AAO) nanotubes with an average pore diameter of less than 100 nm served as the template for the fabrication of nanoporous Pt films using an anodization method. This was achieved by applying a voltage of 40 V in 0.4 M of a phosphoric acid solution at 20 degrees C. To compare the film and nanoporous Pt, layers of approximately 3 nm and 20 nm were coated on both glass substrates and AAO templates using a sputtering technique. FESEM images monitored the formation of nanoporosity by observing the Pt layers covering the upper edges of the AAO nanotubes. Despite their low thickness and the poor long-range order, the EDX and XRD measurements confirmed and uncovered the crystalline properties of the Pt films by comparing the bare and the Pt deposited AAO templates. The nanoporous Pt and Pt thin film sensors were tested in the hydrogen concentration range between 10-50,000 ppm H-2 at room temperature, 50 degrees C, 100 degrees C and 150 degrees C. The results reveal that nanoporous Pt performed higher sensitivity than the Pt thin film and the surface scattering phenomenon can express the hydrogen sensing mechanism of the Pt sensors.
  • Küçük Resim Yok
    Öğe
    Hybrid liquid crystalline zinc phthalocyanine@Cu2O nanowires for NO2 sensor application
    (Elsevier Science Sa, 2021) Sisman, Orhan; Kilinc, Necmettin; Akkus, Unal Ozden; Sama, Jordi; Romano-Rodriguez, Albert; Atilla, Devrim; Gurek, Ayse Gul
    A novel organic-inorganic hybrid conductometric NO2 sensor has been introduced by depositing liquid crystalline zinc oktakisalkylthiophthalocyanine [(C6S)(8)PcZn] on the surface of Cu2O nanowires. Cu2O nano wires were synthesized by electrochemical anodization of Cu films on glass substrates. Surface structures of bare Cu2O and (C6S)(8)PcZn@Cu2O nanowires hybrid structures were monitored by scanning electron microscope (SEM). UV-vis spectrophotometer measurements revealed the heterostructure formation by comparing the absorption profiles of bare Cu2O nanowires, (C6S)(8)PcZn thin film, and (C6S)(8)PcZn@Cu2O hybrid nanowires. The interdigitated transducers (IDT) were used for conductometric gas measurements. The sensing properties of all samples were investigated towards 500 ppb, 1 ppm, 2 ppm, and 5 ppm NO2 under dry airflow in 30 degrees C, 50 degrees C, 100 degrees C, and 150 degrees C. The measurements at 150 degrees C were repeated for (C6S)(8)PcZn film and hybrid sample using the same concentrations of NO2 gas under 38 % relative humidity airflow. In addition, selectivity of hybrid sensor was confirmed with carbon monoxide (CO), hydrogen (H-2) and ethanol (C2H5OH) measurements. Our density functional theory calculations indicate that S atoms play a crucial role in improving the sensor response. The sensing properties and sensing mechanisms of samples were compared and discussed.