The Experts below are selected from a list of 16437 Experts worldwide ranked by ideXlab platform
Tianshou Zhao - One of the best experts on this subject based on the ideXlab platform.
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integrated inorganic membrane Electrode Assembly with layered double hydroxides as ionic conductors for anion exchange membrane water electrolysis
Nano Energy, 2015Co-Authors: Lin Zeng, Tianshou ZhaoAbstract:Abstract In this work, we report a novel integrated inorganic membrane Electrode Assembly (I2MEA) for anion exchange membrane (AEM) water electrolysis by using inorganic Mg-Al layered double hydroxides (Mg-Al LDHs) as an ionic conductor. Mg-Al LDHs synthesized by a two-step approach exhibit high hydroxide ion conductivity and superior stability. The resultant ionic conducting nanoparticles are cold-pressed to form a membrane and mixed with a non-precious electrocatalyst to form the catalyst layer onto each side of the membrane. As such, an I2MEA is formed and used in a water electrolysis setup. It is shown that the present water electrolysis results in a maximum current density of 208 mA cm−2 with 0.1 M NaOH as the electrolyte and a cutoff voltage of 2.2 V at 70 °C. More impressively, using 0.1 M Na2CO3 as the electrolyte, the I2MEAs can continuously electrolyze at 80 mA cm−2 for 600 hours with a decay rate of as low as 100 μV h−1. This superior stability is attributed to the integrated structure that allows hydroxide ions to transport smoothly.
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numerical investigations of effect of membrane Electrode Assembly structure on water crossover in a liquid feed direct methanol fuel cell
Journal of Power Sources, 2009Co-Authors: Weiwei Yang, Tianshou ZhaoAbstract:Abstract A two-phase mass-transport model is employed to investigate the water transport behaviour through the membrane Electrode Assembly (MEA) of a liquid-feed direct methanol fuel cell (DMFC). Emphasis is placed on examining the effects of each constituent component design of the MEA, including catalyst layers, microporous layers and membranes, on each of the three water crossover mechanisms: electro-osmotic drag, diffusion, and convection. The results show that lowering the diffusion flux of water or enhancing the convection flux of water (termed as the back-flow flux) through the membrane are both feasible to suppress water crossover in DMFCs. It is found that the reduction in the diffusion flux of water can be mainly achieved through optimum design of the anode porous layers, as the effect of the cathode porous region on water crossover by diffusion is relatively smaller. On the other hand, the design of the cathode porous layers plays a more important role in increasing the back-flow flux of water from the cathode to anode.
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numerical investigations of effect of membrane Electrode Assembly structure on water crossover in a liquid feed direct methanol fuel cell
Journal of Power Sources, 2009Co-Authors: Weiwei Yang, Tianshou ZhaoAbstract:Abstract A two-phase mass-transport model is employed to investigate the water transport behaviour through the membrane Electrode Assembly (MEA) of a liquid-feed direct methanol fuel cell (DMFC). Emphasis is placed on examining the effects of each constituent component design of the MEA, including catalyst layers, microporous layers and membranes, on each of the three water crossover mechanisms: electro-osmotic drag, diffusion, and convection. The results show that lowering the diffusion flux of water or enhancing the convection flux of water (termed as the back-flow flux) through the membrane are both feasible to suppress water crossover in DMFCs. It is found that the reduction in the diffusion flux of water can be mainly achieved through optimum design of the anode porous layers, as the effect of the cathode porous region on water crossover by diffusion is relatively smaller. On the other hand, the design of the cathode porous layers plays a more important role in increasing the back-flow flux of water from the cathode to anode.
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modeling of water transport through the membrane Electrode Assembly for direct methanol fuel cells
Journal of Power Sources, 2008Co-Authors: Tianshou Zhao, Weiwei YangAbstract:Abstract In this work, a one-dimensional, isothermal two-phase mass transport model is developed to investigate the water transport through the membrane Electrode Assembly (MEA) for liquid-feed direct methanol fuel cells (DMFCs). The liquid (methanol–water solution) and gas (carbon dioxide gas, methanol vapor and water vapor) two-phase mass transport in the porous anode and cathode is formulated based on classical multiphase flow theory in porous media. In the anode and cathode catalyst layers, the simultaneous three-phase (liquid and vapor in pores as well as dissolved phase in the electrolyte) water transport is considered and the phase exchange of water is modeled with finite-rate interfacial exchanges between different phases. This model enables quantification of the water flux corresponding to each of the three water transport mechanisms through the membrane for DMFCs, such as diffusion, electro-osmotic drag, and convection. Hence, with this model, the effects of MEA design parameters on water crossover and cell performance under various operating conditions can be numerically investigated.
Weiwei Yang - One of the best experts on this subject based on the ideXlab platform.
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numerical investigations of effect of membrane Electrode Assembly structure on water crossover in a liquid feed direct methanol fuel cell
Journal of Power Sources, 2009Co-Authors: Weiwei Yang, Tianshou ZhaoAbstract:Abstract A two-phase mass-transport model is employed to investigate the water transport behaviour through the membrane Electrode Assembly (MEA) of a liquid-feed direct methanol fuel cell (DMFC). Emphasis is placed on examining the effects of each constituent component design of the MEA, including catalyst layers, microporous layers and membranes, on each of the three water crossover mechanisms: electro-osmotic drag, diffusion, and convection. The results show that lowering the diffusion flux of water or enhancing the convection flux of water (termed as the back-flow flux) through the membrane are both feasible to suppress water crossover in DMFCs. It is found that the reduction in the diffusion flux of water can be mainly achieved through optimum design of the anode porous layers, as the effect of the cathode porous region on water crossover by diffusion is relatively smaller. On the other hand, the design of the cathode porous layers plays a more important role in increasing the back-flow flux of water from the cathode to anode.
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numerical investigations of effect of membrane Electrode Assembly structure on water crossover in a liquid feed direct methanol fuel cell
Journal of Power Sources, 2009Co-Authors: Weiwei Yang, Tianshou ZhaoAbstract:Abstract A two-phase mass-transport model is employed to investigate the water transport behaviour through the membrane Electrode Assembly (MEA) of a liquid-feed direct methanol fuel cell (DMFC). Emphasis is placed on examining the effects of each constituent component design of the MEA, including catalyst layers, microporous layers and membranes, on each of the three water crossover mechanisms: electro-osmotic drag, diffusion, and convection. The results show that lowering the diffusion flux of water or enhancing the convection flux of water (termed as the back-flow flux) through the membrane are both feasible to suppress water crossover in DMFCs. It is found that the reduction in the diffusion flux of water can be mainly achieved through optimum design of the anode porous layers, as the effect of the cathode porous region on water crossover by diffusion is relatively smaller. On the other hand, the design of the cathode porous layers plays a more important role in increasing the back-flow flux of water from the cathode to anode.
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modeling of water transport through the membrane Electrode Assembly for direct methanol fuel cells
Journal of Power Sources, 2008Co-Authors: Tianshou Zhao, Weiwei YangAbstract:Abstract In this work, a one-dimensional, isothermal two-phase mass transport model is developed to investigate the water transport through the membrane Electrode Assembly (MEA) for liquid-feed direct methanol fuel cells (DMFCs). The liquid (methanol–water solution) and gas (carbon dioxide gas, methanol vapor and water vapor) two-phase mass transport in the porous anode and cathode is formulated based on classical multiphase flow theory in porous media. In the anode and cathode catalyst layers, the simultaneous three-phase (liquid and vapor in pores as well as dissolved phase in the electrolyte) water transport is considered and the phase exchange of water is modeled with finite-rate interfacial exchanges between different phases. This model enables quantification of the water flux corresponding to each of the three water transport mechanisms through the membrane for DMFCs, such as diffusion, electro-osmotic drag, and convection. Hence, with this model, the effects of MEA design parameters on water crossover and cell performance under various operating conditions can be numerically investigated.
Tebello Nyokong - One of the best experts on this subject based on the ideXlab platform.
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molecular catalysis of the oxygen reduction reaction by iron porphyrin catalysts tethered into nafion layers an electrochemical study in solution and a membrane Electrode Assembly study in fuel cells
Journal of Power Sources, 2012Co-Authors: Qinggang He, Tawanda Mugadza, Xiongwu Kang, Xiaobing Zhu, Shaowei Chen, John B. Kerr, Tebello NyokongAbstract:Abstract This study was motivated by the need for improved understanding of the kinetics and transport phenomena in a homogeneous catalyst system for the oxygen reduction reaction (ORR). Direct interaction between the sulfonic groups of Nafion and an Fe(III) meso-tetra( N -methyl-4-pyridyl) porphine chloride (Fe(III)TMPyP) compound was observed using FTIR and in situ UV–Vis spectroelectrochemical characterizations. A positive shift of the half wave potential value ( E 1/2 ) for ORR on the iron porphyrin catalyst (Fe(III)TMPyP) was observed upon addition of a specific quantity of Nafion ionomer on a glassy carbon working Electrode, indicating not only a faster charge transfer rate but also the role of protonation in the oxygen reduction reaction (ORR) process. A membrane Electrode Assembly (MEA) was made as a sandwich of a Pt-coated anode, a Nafion ® 212 membrane, and a Fe(III)TMPyP + Nafion ionomer-coated cathode. This three-dimensional catalysis system has been demonstrated to be working in a H 2 /O 2 proton exchange membrane (PEM) fuel cell test.
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Molecular catalysis of the oxygen reduction reaction by iron porphyrin catalysts tethered into Nafion layers: An electrochemical study in solution and a membrane-Electrode-Assembly study in fuel cells
Journal of Power Sources, 2012Co-Authors: Tawanda Mugadza, Xiongwu Kang, Xiaobing Zhu, Shaowei Chen, John B. Kerr, Tebello NyokongAbstract:Abstract This study was motivated by the need for improved understanding of the kinetics and transport phenomena in a homogeneous catalyst system for the oxygen reduction reaction (ORR). Direct interaction between the sulfonic groups of Nafion and an Fe(III) meso-tetra( N -methyl-4-pyridyl) porphine chloride (Fe(III)TMPyP) compound was observed using FTIR and in situ UV–Vis spectroelectrochemical characterizations. A positive shift of the half wave potential value ( E 1/2 ) for ORR on the iron porphyrin catalyst (Fe(III)TMPyP) was observed upon addition of a specific quantity of Nafion ionomer on a glassy carbon working Electrode, indicating not only a faster charge transfer rate but also the role of protonation in the oxygen reduction reaction (ORR) process. A membrane Electrode Assembly (MEA) was made as a sandwich of a Pt-coated anode, a Nafion ® 212 membrane, and a Fe(III)TMPyP + Nafion ionomer-coated cathode. This three-dimensional catalysis system has been demonstrated to be working in a H 2 /O 2 proton exchange membrane (PEM) fuel cell test.
Wicaksono, Muhamad Akbar - One of the best experts on this subject based on the ideXlab platform.
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Analisis Pengaruh Variasi Rasio Berat Nafion/Karbon Pada Lapisan Katalis Membrane Electrode Assembly Terhadap Performa Elektrokimia PEM Fuel Cell
2021Co-Authors: Wicaksono, Muhamad AkbarAbstract:Saat ini, penggunaan fuel cell semakin meningkat dari tahun ketahun, hal tersebut terjadi karena fuel cell memiliki efisiensi tinggi, dan ramah terhadap lingkungan. Akan tetapi terdapat permasalahan terkait kinerja fuel cell, dan biaya pembuatan yang relatif mahal, oleh karena itu dilakukan pengembangan pada Membrane Electrode Assembly (MEA) yang merupakan bagian paling vital dan mahal pad PEMFC, untuk dapat meningkatkan pemanfaatan Pt dan luas permukaan elektrokimia aktif. Tujuan penelitian ini adalah untuk menganalisis variasi rasio berat nafion dengan karbon penyangga (N/C) yaitu 0,45, 0,6, dan 0,75 pada lapisan katalis MEA terhadap morfologi dan performa PEMFC.Metode deposisi yang digunakan pada penelitian ini adalah doctor blade method. Berdasarkan hasil pengujian SEM sampel lapisan katalis dengan rasio berat N/C 0,6 terbentuk agregat nafion pada katalis Pt-C dan nafion membentuk ikatan yang seragam dan terhubung, pada pengujian cyclic voltammetry didapat nilai electrochemical surface area sebesar 37 m2/g. Dan hasil pengujian EIS, dengan nilai Rct terendah yaitu sebesar 91,59 Ω.cm2, serta mendapatkan nilai power density tertinggi pada pengujian polarisasi yaitu sebesar 6,75 mW.cm-2. ================================================================================================= Currently, the use of fuel cells is increasing from year to year, this happens because fuel cells have high efficiency, and are friendly to the environment. However, there are problems related to the performance of the fuel cell, and the relatively expensive manufacturing cost, therefore the membrane Electrode Assembly (MEA) which is the most vital and expensive part of the PEMFC is developed, in order to increase the utilization of Pt and the active electrochemical surface area. The purpose of this study was to analyze the variation of the weight ratio of nafion with carbon buffer (N/C) ie 0,45, 0,6, and 0,75 in the MEA catalyst layer on the morphology and performance of PEMFC. The deposition method used in this study is the doctor blade method. Based on the results of the SEM test of the catalyst layer sample with a weight ratio of N/C 0,6, nafion aggregates on the Pt-C catalyst and the nafion forms a uniform and connected bond, in the cyclic voltammetry test the electrochemical surface area value is 37 m2/g. And the results of the EIS test, with the lowest Rct value of 91.59 .cm2, and getting the highest power density value in the polarization test, which is 6.75 mW.cm-
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Analisis Pengaruh Variasi Rasio Berat Nafion/Karbon pada Lapisan Katalis Membrane Electrode Assembly terhadap Performa Elektrokimia PEM Fuel Cell (PEMFC)
'Lembaga Penelitian dan Pengabdian kepada Masyarakat ITS', 2021Co-Authors: Wicaksono, Muhamad Akbar, Noerochim Lukman, Purniawan AgungAbstract:Saat ini, penggunaan fuel cell semakin meningkat dari tahun ketahun, hal tersebut terjadi karena fuel cell memiliki efisiensi tinggi, dan ramah terhadap lingkungan. Akan tetapi terdapat permasalahan terkait kinerja fuel cell, dan biaya pembuatan yang relatif mahal, oleh karena itu dilakukan pengembangan pada Membrane Electrode Assembly (MEA) yang merupakan bagian paling vital dan mahal pad PEMFC, untuk dapat meningkatkan pemanfaatan Pt dan luas permukaan elektrokimia aktif. Tujuan penelitian ini adalah untuk menganalisis variasi rasio berat nafion dengan karbon penyangga (N/C) yaitu 0,45, 0,6, dan 0,75 pada lapisan katalis MEA terhadap morfologi dan performa PEMFC. Metode deposisi yang digunakan pada penelitian ini adalah doctor blade method. Berdasarkan hasil pengujian SEM sampel lapisan katalis dengan rasio berat N/C 0,6 terbentuk agregat nafion pada katalis Pt-C dan nafion membentuk ikatan yang seragam dan terhubung, pada pengujian cyclic voltammetry didapat nilai electrochemical surface area sebesar 37 m2/g. Dan hasil pengujian EIS, dengan nilai Rct terendah yaitu sebesar 91,59 Ω.cm2, serta mendapatkan nilai power density tertinggi pada pengujian polarisasi yaitu sebesar 6,75 mW.cm-2
Devinder Mahajan - One of the best experts on this subject based on the ideXlab platform.
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durability and characterization studies of polymer electrolyte membrane fuel cell s coated aluminum bipolar plates and membrane Electrode Assembly
Journal of Power Sources, 2009Co-Authors: Y Hung, H Tawfik, Devinder MahajanAbstract:Abstract Coated aluminum bipolar plates demonstrate better mechanical strength, ease of manufacturability, and lower interfacial contact resistance (ICR) than graphite composite plates in polymer electrolyte membrane (PEM) fuel cell applications. In this study, coated aluminum and graphite composite bipolar plates were installed in separate single PEM fuel cells and tested under normal operating conditions and cyclic loading. After 1000 h of operation, samples of both the bipolar plates and the membrane Electrode Assembly (MEA) were collected from both the cathode and the anode sides of the cell and characterized to examine the stability and integrity of the plate coating and evaluate possible changes of the ionic conductivity of the membrane due any electrochemical reaction with the coating material. Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis were performed on the land and valley surfaces of the reactant flow fields at both the anode and the cathode sides of the bipolar plates. The measurements were superimposed on the reference to identify possible zones of anomalies for the purpose of conducting focused studies in these locations. The X-ray diffraction (XRD) analysis of samples scraped from the anode and cathode Electrodes of the MEA showed the tendency for catalyst growth that could result in power degradation. Samples of the by-product water produced during the single fuel cell operation were also collected and tested for the existence of chromium, nickel, carbon, iron, sulfur and aluminum using mass spectroscopy techniques. The EDX measurements indicated the possibility of dissociation and dissolution of nickel chrome that was used as the binder for the carbide-based corrosion-resistant coating with the aluminum substrate.