Filters

2017 - 201912020 - 20261
Reset filters

Settings

Author: Ozden, AdnanCOAR Access Rights: open access

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Conference Object
    Citation - WoS: 28
    Citation - Scopus: 35
    Enhancement of Direct Methanol Fuel Cell Performance Through the Inclusion of Zirconium Phosphate
    (Pergamon-elsevier Science Ltd, 2017) Ozden, Adnan; Ercelik, Mustafa; Ozdemir, Yagmur; Devrim, Yilser; Colpan, C. Ozgur
    Nafion/zirconium hydrogen phosphate (ZrP) composite membranes containing 2.5 wt.% ZrP (NZ-2.5) or 5 wt.% ZrP (NZ-5) were prepared to improve the performance of a direct methanol fuel cell (DMFC). The influence of ZrP content on the Nafion matrix is assessed through characterization techniques, such as Thermogravimetric Analysis (TGA), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS), and water uptake measurement. Performance testings of the DMFCs based on these composite membranes as well as commercial Nafion (R) 115 membrane were performed using a computer aided fuel cell test station for different values of cell temperature (40 degrees C, 60 degrees C, 80 degrees C, and 100 degrees C) and methanol concentration (0.75 M, 1.00 M, and 1.50 M). Characterization studies indicated that incorporation of ZrP into polymer matrix enhanced the water uptake and proton conductivity values of Nafion membrane. The results of the performance tests showed that the Membrane Electrode Assembly (MEA) having NZ-2.5 provided the highest performance with the peak power density of 551.52 W/m(2) at 100 degrees C and 1.00 M. Then, the performances of the MEAs having the same NZ-2.5 membrane but different cathode catalysts were investigated by fabricating two different MEAs using cathode catalysts made of Pt/C-ZrP and Pt/C (HiSPEC (R) 9100). According to the results of these experiments, the MEA having NZ-2.5 membrane and Pt/C (HiSPEC (R) 9100) cathode catalyst containing 10 wt.% of ZrP exhibited the highest performance with the peak power density of 620.88 W/m(2) at 100 degrees C and 1.00 M. In addition, short-term stability tests were conducted for all the MEAs. The results of the stability tests revealed that introduction of ZrP to commercial (HiSPEC (R) 9100) cathode catalyst improves its stability characteristics. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
  • Thumbnail Image
    Article
    Citation - WoS: 3
    Citation - Scopus: 3
    A Review on Membranes for Anion Exchange Membrane Water Electrolyzers
    (Pergamon-Elsevier Science Ltd, 2026) Altinisik, Hasan; Celebi, Ceren; Ozden, Adnan; Devrim, Yilser; Colpan, C. Ozgur
    Anion exchange membrane water electrolyzers (AEMWEs) - using water and renewable electricity as the input - provide a sustainable pathway to hydrogen production. AEMWEs perform the cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) with modest overpotentials at practical current densities (>1 A cm(-2)). The recent catalysis, component, and system-level breakthroughs have enabled significant improvements in current densities and energetic efficiencies. The challenge, however, is to maintain these impressive activities and efficiencies through long-term operation at scale. High-performance, efficient, stable, and economically viable AEMWEs require high-performance, low-cost, and scalable anion exchange membranes (AEMs). This Review provides an overview of physical, chemical, and transport properties of commercial and non-commercial AEMs. The article discusses the operating principles, structures, characteristics, strengths, and weaknesses of conventional and emerging AEMs, along with their performance and stability implications in AEMWEs. The article highlights the characteristics that have intricate implications on performance, stability, and cost. It discusses recent advances and best practices to combine high-performance, efficiency, stability, and low-cost in a single AEM structure. The Review highlights the trade-offs between AEM characteristics, with an overview of emerging approaches that would overcome performance, stability, and cost challenges. The Review concludes by highlighting the research gaps and providing research directions with the potential to take the technology a step closer to wide-scale deployment.