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Article Citation - WoS: 61Citation - Scopus: 73Evaluation of Sulfonated Polysulfone/Zirconium Hydrogen Phosphate Composite Membranes for Direct Methanol Fuel Cells(Pergamon-elsevier Science Ltd, 2017) Ozden, Adnan; Ercelik, Mustafa; Devrim, Yilser; Colpan, C. Ozgur; Hamdullahpur, FeridunDirect methanol fuel cell (DMFC) technology has advanced perceivably, but technical challenges remain that must be overcome for further performance improvements. Thus, in this study, sulfonated polysulfone/zirconium hydrogen phosphate (SPSf/ZrP) composite membranes with various sulfonation degrees (20%, 35%, and 42%) and a constant concentration of ZrP (2.5%) were prepared to mitigate the technical challenges associated with the use of conventional Nafion (R) membranes in DMFCs. The composite membranes were investigated through Scanning Electron Microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS), Thermogravimetric Analysis (TGA), oxidative stability and water uptake measurements, and single cell testing. Comparison was also made with Nafion (R) 115. Single cell tests were performed under various methanol concentrations and cell temperatures. Stability characteristics of the DMFCs under charging and discharging conditions were investigated via 1200 min short-term stability tests. The response characteristics of the DMFCs under dynamic conditions were determined at the start-up and shut-down stages. Composite membranes with sulfonation degrees of 35% and 42% were found to be highly promising due to their advanced characteristics with respect to proton conductivity, water uptake, thermal resistance, oxidative stability, and methanol suppression. For the whole range of parameters studied, the maximum power density obtained for SPSf/ZrP-42 (119 mW cm (2)) was found to be 13% higher than that obtained for Nafion (R) 115 (105 mW cm (2)). (C) 2017 Elsevier Ltd. All rights reserved.Conference Object Citation - WoS: 82Citation - Scopus: 92Graphene Based Catalyst Supports for High Temperature Pem Fuel Cell Application(Pergamon-elsevier Science Ltd, 2018) Devrim, Yilser; Arica, Elif Damla; Albostan, AyhanIn this study, the effect of graphene nanoplatelet (GNP) and graphene oxide (GO) based carbon supports on polybenzimidazole (PBI) based high temperature proton exchange membrane fuel cells (HT-PEMFCs) performances were investigated. Pt/GNP and Pt/GO catalysts were synthesized by microwave assisted chemical reduction support. X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Brauner, Emmet and Teller (BET) analysis and high resolution transmission electron microscopy (HRTEM) were used to investigate the microstructure and morphology of the as-prepared catalysts. The electrochemical surface area (ESA) was studied by cyclic voltammetry (CV). The results showed deposition of smaller Pt nanoparticles with uniform distribution and higher ECSA for Pt/GNP compared to Pt/GO. The Pt/GNP and Pt/GO catalysts were tested in 25 cm(2) active area single HT-PEMFC with H-2/air at 160 degrees C without humidification. Performance evaluation in HT-PEMFC shows current densities of 0.28, 0.17 and 0.22 A/cm(2) for the Pt/GNP, Pt/C and Pt/GO catalysts based MEAs at 160 degrees C, respectively. The maximum power density was obtained for MEA prepared by Pt/GNP catalyst with H-2/Air dry reactant gases as 0.34, 0.40 and 0.46 W/cm(2) at 160 degrees C, 175 degrees C and 190 degrees C, respectively. Graphene based catalyst supports exhibits an enhanced HT-PEMFC performance in both low and high current density regions. The results indicate the graphene catalyst support could be utilized as the catalyst support for HT-PEMFC application. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Conference Object Citation - WoS: 28Citation - Scopus: 34Enhancement 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. OzgurNafion/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.Article Citation - WoS: 6Citation - Scopus: 7Fabrication and Performance Evaluation of Graphene-Supported Ptru Electrocatalyst for High-Temperature Electrochemical Hydrogen Purification(Pergamon-elsevier Science Ltd, 2023) Bal, Ilay Bilge; Durmus, Gizem Nur Bulanik; Devrim, YilserThe main aim of this study is to investigate the high-temperature electrochemical hydrogen purification (HT-ECHP) performances of graphene nanoplatelet (GNP) support material decorated with platinum (Pt) and platinum-ruthenium (PtRu) nanoparticles prepared by microwave irradiation technique. Prepared catalysts coupled to the phosphoric acid doped polybenzimidazole (PBI) membrane for HT-ECHP application. The structural and electrochemical properties of the catalysts were examined by thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Transition electron microscopy (TEM) and cyclic voltammetry (CV) analyses. The characterization results indicate that the catalysts provided the necessary properties for HT-ECHP application. The HT-ECHP performances are investigated with reformate gas mixture containing hydrogen (H2), carbon dioxide (CO2) and carbon monoxide (CO) in the range of 140-180 & DEG;C. The results show that the electrochemical purification performances of the catalysts increase with increasing operating temperature. The highest H2 purification performance is obtained with PtRu/GNP catalyst. The high electrochemical H2 purification performance of the PtRu/GNP catalyst can be attributed to the strong synergistic interactions between Pt and Ru particles decorated on the GNP. These results advocate that the PtRu/GNP catalyst is a hopeful catalyst for HT-ECHP application. & COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 8Experimental and Modeling Studies of a High-Temperature Electrochemical Hydrogen Compressor(Pergamon-elsevier Science Ltd, 2024) Durmus, Gizem Nur Bulanik; Kuzu, Cemil; Devrim, Yilser; Colpan, C. OzgurSome non-technical factors such as economics and logistics prevent hydrogen (H2) tech-nologies from becoming more widespread in daily life. Today, the prevalence of H2 tech-nologies requires new technological developments. Electrochemical hydrogen compressors (ECHC) are of great interest due to their ability to pressurize and purify in one step. In this study, the electrochemical H2 compression performance of high phosphoric acid (PA) doped poly 2,2-m-phenylene-5,5-benzimidazole (PBI) membrane-based HT-ECHC under high temperature and non-humid conditions was investigated through both an experimental and a numerical approach. The H2 compression capacity of HT-ECHC at different operating voltages was examined by performance tests at 160 degrees C, and it was determined that the electrochemical compression performance increased with increasing operating voltage. It was observed that the current density values also increased with increasing voltage, and it was determined that a current density of 61.2 A was obtained at 1 V. As a result of the tests, H2 was successfully compressed from atmospheric pressure to 60 bar by HT-ECHC without any gas leakage. The results of the developed model were compared with the experimental performance test data, and the variation of molar flow, cell voltage, and cell efficiency over time was examined. It has been determined that the back diffusion from the cathode to the anode in the cell increases with the increasing operating voltage of HT-ECHC and therefore the cell efficiency decreases. It has been evaluated that the developed model and experimental results are in good agreement. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 55Citation - Scopus: 63Development of 500 W Pem Fuel Cell Stack for Portable Power Generators(Pergamon-elsevier Science Ltd, 2015) Devrim, Yilser; Devrim, Huseyin; Eroglu, InciPolymer Electrolyte Membrane Fuel Cell (PEMFC) portable power generators are gaining importance in emergency applications. In this study, an air-cooled PEMFC stack was designed and fabricated for net 500 W power output. Gas Diffusion Electrodes (GDE's) were manufactured by ultrasonic spray coating technique. Stack design was based on electrochemical data obtained at 0.60 V was 0.5 A/cm(2) from performance tests of a single cell having the same membrane electrode assemblies (MEA) that had an active area of 100 cm(2). Graphite bipolar plates were designed and machined by serpentines type flow. The stack comprising of 24 cells was assembled with external fixing plates. The stack temperature was effectively regulated by the cooling fan based on on-off control system. A maximum power of 647 W was obtained from the stack. The PEMFC stack was stable during start-up and shutdown cycling testing for 7 days at 65 degrees C in H-2/air at a constant cell voltage. Copyright (c) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Conference Object Citation - WoS: 85Citation - Scopus: 92Enhancement of Pem Fuel Cell Performance at Higher Temperatures and Lower Humidities by High Performance Membrane Electrode Assembly Based on Nafion/Zeolite Membrane(Pergamon-elsevier Science Ltd, 2015) Devrim, Yilser; Albostan, AyhanThis work reports the preparation of Nafion/zeolite composite membranes with different zeolite loading. The structure of the Nafion/zeolite composite membranes are investigated by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and by thermogravimetric analysis (TGA). The introduction of zeolite particles into the Nafion matrix helps to improve the water uptake, proton conductivity and thermal stability of the nanocomposite membranes compared to the virgin Nafion membrane. The SEM analyses have proved the uniform and homogeneous distribution of zeolite in composite membranes. The composite membranes are tested in a single PEMFC with a 5 cm(2) active area operating at the temperature range of 75-120 degrees C and in humidified under 50% relative humidity (RH) and fully humidified conditions. Single PEMFC tests show that Nafion/zeolite composite membrane is more stable and also performed better than virgin Nafion membrane at low humidity condition. The results indicate the Nafion/zeolite composite membranes could be utilized as the proton exchange membranes for PEMFC. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 68Citation - Scopus: 69Composite Membrane by Incorporating Sulfonated Graphene Oxide in Polybenzimidazole for High Temperature Proton Exchange Membrane Fuel Cells(Pergamon-elsevier Science Ltd, 2022) Devrim, Yilser; Durmus, Gizem Nur BulanikThe objective of this work is to examine the polybenzimidazole (PBI)/sulfonated graphene oxide (sGO) membranes as alternative materials for high-temperature proton exchange membrane fuel cell (HT-PEMFC). PBI/sGO composite membranes were characterized by TGA, FTIR, SEM analysis, acid doping&acid leaching tests, mechanical analysis, and proton conductivity measurements. The proton conductivity of composite membranes was considerably enhanced by the existence of sGO filler. The enhancement of these properties is related to the increased content of -SO3H groups in the PBI/sGO composite membrane, increasing the channel availability required for the proton transport. The PBI/sGO membranes were tested in a single HT-PEMFC to evaluate high-temperature fuel cell performance. Amongst the PBI/sGO composite membranes, the membrane containing 5 wt. % GO (PBI/sGO-2) showed the highest HT-PEMFC performance. The maximum power density of 364 mW/cm(2) was yielded by PBI/sGO-2 membrane when operating the cell at 160 degrees C under non humidified conditions. In comparison, a maximum power density of 235 mW/cm(2) was determined by the PBI membrane under the same operating conditions. To investigate the HT-PEMFC stability, long-term stability tests were performed in comparison with the PBI membrane. After a long-term performance test for 200 h, the HT-PEMFC performance loss was obtained as 9% and 13% for PBI/sGO-2 and PBI membranes, respectively. The improved HT-PEMFC performance of PBI/sGO composite membranes suggests that PBI/sGO composites are feasible candidates for HT-PEMFC applications. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 19Citation - Scopus: 21Development of Effective Bimetallic Catalyst for High-Temperature Pem Fuel Cell To Improve Co Tolerance(Wiley, 2021) Al-Tememy, Mogdam Gassy Hussein; Devrim, YilserIn this study, it is aimed to examine the effect of multi-walled carbon nanotube doped graphene nanoplatelet (MWCNT-GNP) supported PtPd bimetallic catalyst on the performance of the high-temperature proton-exchange membrane fuel cell (HT-PEMFC). In addition, PtPd/GNP and PtPd/MWCNT bimetallic catalysts were also investigated for performance comparison. The characterizations of these catalysts were examined by ICP-MS, XRD, HR-TEM, and TGA analysis. The electrochemical characterizations of the catalysts were performed for both cyclic voltammetry (CV) and CO stripping experiments, as well as HT-PEMFC tests. The specific surface area (SSA) for PtPd/GNP and PtPd/MWCNT catalysts was obtained as 148 and 137 m(2)/g, respectively, while the highest SSA was achieved as 164 m(2)/g for PtPd/MWCNT-GNP. The performance of the catalysts was confirmed with the HT-PEMFC tests, based on the H-2/air and reformate gas/air experiments. The electrocatalytic results display that PdPt bimetallic catalysts exhibited higher catalytic property than that of commercial Pt/C catalyst. The highest performance was achieved with PtPd/MWCNT-GNP catalyst as 0.390 and 0.310 W/cm(2)at 160 degrees C for H-2/air and reformat/air, respectively. The obtained results indicate that the PtPd/MWCNT-GNP catalyst is appropriate for HT-PEMFC operations.Article Citation - WoS: 15Citation - Scopus: 15Optimal Design and Technoeconomic Analysis of On-Site Hydrogen Refueling Station Powered by Wind and Solar Photovoltaic Hybrid Energy Systems(Pergamon-elsevier Science Ltd, 2025) Ozturk, Reyhan Atabay; Devrim, YilserIn this study, a grid-connected on-site hydrogen filling station (HRS) integrated with renewable energy systems is designed and examined for different daily hydrogen refueling capacities. The installation location of the HRS is selected in Izmir (Turkey) and daily solar radiation and wind speed data are used in the calculations. The HRS station was integrated with a hybrid energy system using photovoltaic panels (PV), wind turbine (WT) and PV/ WT and five different daily refueling scenarios were investigated. A techno-economic analysis is conducted for the designed HRS system, considering the initial investment capital, installation and operating costs. The levelized cost of hydrogen (LCOH) is evaluated according to different refueling capacity scenarios, periods of operation and renewable energy installation capacities. The lowest LCOH is obtained as 4.5 /kg H2 in the PVintegrated HRS system for a 20-year investment scenario. The results prove the suitability of the HRS system for integrating renewable energy in the identified region. It is recommended to integrate analytical models for the system components to increase the reliability of the design and optimization process in future planned studies.
