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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.Conference Object Citation - WoS: 98Citation - Scopus: 101Experimental Investigation of Co Tolerance in High Temperature Pem Fuel Cells(Pergamon-elsevier Science Ltd, 2018) Devrim, Yilser; Albostan, Ayhan; Devrim, HuseyinIn the present work, the effect of operating a high temperature proton exchange membrane fuel cell (HT-PEMFC) with different reactant gases has been investigated throughout performance tests. Also, the effects of temperature on the performance of a HT-PEMFC were analyzed at varying temperatures, ranging from 140 degrees C to 200 degrees C. Increasing the operating temperature of the cell increases the performance of the HT-PEMFC. The optimum operating temperature was determined to be 160 degrees C due to the deformations occurring in the cell components at high working temperatures. To investigate the effects of CO on the performance of HT-PEMFC, the CO concentration ranged from 1 to 5 vol %. The current density at 0.6 V decreases from 0.33 A/cm(2) for H-2 to 0.31 A/cm(2) for H-2 containing 1 vol % CO, to 0.29 A/cm(2) for 3 vol % CO, and 0.25 A/cm(2) for 5 vol % CO, respectively. The experimental results show that the presence of 25 vol % CO2 or N-2 has only a dilution effect and therefore, there is a minor impact on the HT-PEMFC performance. However, the addition of CO to H-2/N-2 or H-2/CO2 mixtures increased the performance loss. After longterm performance test for 500 h, the observed voltage drop at constant current density was obtained as similar to 14.8% for H-2/CO2/CO (75/22/3) mixture. The overall results suggest that the anode side gas mixture with up to 5 vol % CO can be supplied to the HT-PEMFC stack directly from the reformer. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 145Citation - Scopus: 163Polybenzimidazole Based Nanocomposite Membranes With Enhanced Proton Conductivity for High Temperature Pem Fuel Cells(Pergamon-elsevier Science Ltd, 2017) Ozdemir, Yagmur; Uregen, Nurhan; Devrim, YilserIn this study, phosphoric acid doped PBI nanocomposite membranes were prepared by dispersion of various amounts of inorganic nanoparticles in PBI polymer followed by phosphoric acid (H3PO4) doping for high temperature proton exchange membrane fuel cells (HT-PEMFC). All of the PBI composite membranes were cast from the same FBI polymer with the same molecular weight. Titanium dioxide (TiO2), silicon dioxide (SiO2) and inorganic proton conductor zirconium phosphate (ZrP) were used as inorganic fillers. The PBI based composite membranes were characterized in terms of their acid uptake and acid leaching properties, mechanical properties, chemical stabilities in N-N Dimethylacetamide (DMAc) and impedance analyses. Thermal gravimetric analysis confirmed the improved thermal stability of the PBI composite membranes. The existence of inorganic fillers was improved the acid retention capability. Electrochemical Impedance Spectroscopy (EIS) showed that the introduction of 5 wt. % SiO2 or 5 wt. % ZrP helps to increase proton conductivity. The composite membrane with TiO2 retained low conductivity values than pristine PBI and this is a result of its non-uniform membrane structure. The highest proton conductivity of 0.200 S/cm was obtained for PBI/ZrP composite membrane with the highest value of H3PO4 doping level. Nyquist plots are drawn for all the membranes at different temperatures and the plots showed good fit with Randel's circuit. As a result the experimental results suggested that the PBI based composite membranes may be a promising electrolyte used in HT-PEMFC. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 92Citation - Scopus: 103Fabrication and Characterization of Cross-Linked Polybenzimidazole Based Membranes for High Temperature Pem Fuel Cells(Pergamon-elsevier Science Ltd, 2017) Ozdemir, Yagmur; Ozkan, Necati; Devrim, YilserIn this study different types of crosslinked polybenzimidazole (PBI) membranes were compared as high temperature proton exchange membrane fuel cells (HT-PEMFC). Cross-linking of PBI was performed with different cross-linkers including bisphenol A diglycidyl ether (BADGE), ethylene glycol diglycidyl ether (EGDE), alpha-alpha'-dibromo-p-xylene (DBpX), and terephthalaldehyde (TPA). The crosslinked membranes have been characterized by thermogravimetric analysis, scanning electron microscopy, acid uptake and impedance analyses. The crosslinking of the PBI polymer matrix helps to improve the acid retention properties. PBI/BADGE presented the highest acid retention properties. Proton conductivities of the membranes were comparable to that of commercial membranes. Conductivity values up to 0.151 S.cm(-1) were obtained at 180 degrees C with PBI/DBpX membranes. Gas diffusion electrodes (GDE) were fabricated by an ultrasonic coating technique with 0.6 mg Pt.cm(-2) catalyst loading for both anode and cathode. The crosslinked membranes were tested in a single HT-PEMFC with a 5 cm(2) active area at 165 degrees C without humidification. PBI/BADGE crosslinked membranes demonstrated stability and high performance on single cell HT-PEMFC tests. The maximum power density for PBI/BADGE was determined as 0.123 W. cm(-2). As a result, the experimental results suggested that the PBI/ BADGE and PBI/DBpX cross-linked membranes are promising electrolyte options for HT-PEMFC. (C) 2017 Elsevier Ltd. All rights reserved.Article Citation - WoS: 157Citation - Scopus: 171Development of Polybenzimidazole/Graphene Oxide Composite Membranes for High Temperature Pem Fuel Cells(Pergamon-elsevier Science Ltd, 2017) Uregen, Nurhan; Pehlivanoglu, Kubra; Ozdemir, Yagmur; Devrim, YilserIn this study, phosphoric acid doped Polybenzimidazole/Graphene Oxide (PBI/GO) nano composite membranes were prepared by dispersion of various amounts of GO in PBI polymer matrix followed by phosphoric acid doping for high temperature proton exchange membrane fuel cell (HT-PEMFC) application. The structure of the PBI/GO composite membranes was investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and by thermogravimetric analysis (TGA). The introduction of GO into the FBI polymer matrix helps to improve the acid doping, proton conductivity and acid leaching properties. The SEM analyses have proved the uniform and homogeneous distribution of GO in composite membranes. The composite membranes were tested in a single HT-PEMFC with a 5 cm(2) active area at 165 degrees C without humidification. HT-PEMFC tests show that PBI/ GO composite membrane with 2 wt. % GO content performed better than bare PBI membrane at non humidified condition. At ambient pressure and 165 degrees C, the maximum power density of the PBI/GO-1 membrane can reach 0.38 W/cm(2), and the current density at 0.6 V is up to 0.252 A/cm(2), with H-2/air. The results indicate the PBI/GO composite membranes could be utilized as the proton exchange membranes for HT-PEMFC. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Conference Object Citation - WoS: 134Citation - Scopus: 148Polybenzimidazole/Sio2< Hybrid Membranes for High Temperature Proton Exchange Membrane Fuel Cells(Pergamon-elsevier Science Ltd, 2016) Devrim, Yilser; Devrim, Huseyin; Eroglu, InciPolybenzimidazole/Silicon dioxide (PBI/SiO2) hybrid membranes were prepared and characterized as alternative materials for high temperature proton exchange membrane fuel cell (HT-PEMFC). The PBI/SiO2 membranes were cast from a PBI polymer synthesized in the laboratory and contained 5 wt. % SiO2 as inorganic filler. Scanning electron microscopy (SEM) analysis showed that the uniform and homogeneous distribution of SiO2 particles in the hybrid membrane. The existence SiO2 has improved the acid retention and proton conductivity properties. A maximum conductivity of 0.1027 S/cm at 180 degrees C was obtained for the PBI/SiO2 hybrid membrane. Gas diffusion electrodes (GDE) were fabricated by ultrasonic coating technique with 1 mg Pt/cm(2) catalyst loading for both anode and cathode. The membranes were tested in a single HT-PEMFC with a 5 cm(2) active area operating at the temperature range of 140 degrees C-180 degrees C. Single HT-PEMFC tests indicated that PBI/SiO2 hybrid membrane was more stable and also performed better than pristine PBI membrane. Maximum current density was observed for PBI/SiO2 membrane at 165 degrees C and cell voltage of 0.6 V as 0.24 A/cm(2). The results suggested that PBI/SiO2 hybrid membrane is promising electrolytes for HT-PEMFC with improved fuel cell performance. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 14Citation - Scopus: 14High-Temperature Electrochemical Hydrogen Separation From Reformate Gases Using Pbi/Mof Composite Membrane(Pergamon-elsevier Science Ltd, 2023) Durmus, Gizem Nur Bulanik; Eren, Enis Oguzhan; Devrim, Yilser; Colpan, C. Ozgur; Ozkan, NecatiIn this paper, the high-temperature electrochemical Hydrogen (H2) purification perfor-mance of a polybenzimidazole/UIO-66 metal-organic framework (PBI/UIO-66) membrane is investigated and analyzed at different values of current, temperature, and reformate feed composition. Purification measurements show that a significant reduction in gas impu-rities can be obtained. In the performance tests, three different ratios of reformate gas (RG) (H2:carbon dioxide (CO2):carbon monoxide (CO)) as RG-1= (75:25:0), RG-2= (75:22:3), and RG-3= (95:0:5) were used. The highest purification values were observed at 160 & DEG;C as 99.999%, 99.931%, and 99.708% for RG-1, RG-2, and RG-3, respectively. The obtained results show that an electrochemical H2 purification (ECHP) based on PBI/UIO-66 composite membrane is promising for H2 purification.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 38Citation - Scopus: 41Preparation of Polybenzimidazole/Zif-8 and Polybenzimidazole/Uio-66 Composite Membranes With Enhanced Proton Conductivity(Pergamon-elsevier Science Ltd, 2022) Eren, Enis Oguzhan; Ozkan, Necati; Devrim, YilserMetal-organic frameworks (MOFs) are considered emerging materials as they further improve the various properties of polymer membranes used in energy applications, ranging from electrochemical storage and purification of hydrogen to proton exchange membrane fuel cells. Herein, we fabricate composite membranes consisting of polybenzimidazole (PBI) polymer as a matrix and MOFs as filler. Synthesis of ZIF-8 and UiO-66 MOFs are conducted through a typical solvothermal method, and composite membranes are fabricated with different MOF compositions (e.g., 2.5, 5.0, 7.5, and 10.0 wt %). We report a significant improvement in proton conductivity compared with the pristine PBI; for example, more than a three-fold increase in conductivity is observed when the PBI-UiO66 (10.0 wt %) and PBI-ZIF8 (10.0 wt %) membranes are tested at 160 degrees C. Proton conductivities of the composite membranes vary between 0.225 and 0.316 S cm(-1) at 140 and 160 degrees C. For the comparison, pure PBI exhibits 0.060 S cm(-1) at 140 degrees C and 0.083 S cm(-1) at 160 degrees C. However, we also report a decrease in permeability and mechanical stability with the composite membranes. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
