scholarly journals Subsize Pt-based intermetallic compound enables long-term cyclic mass activity for fuel-cell oxygen reduction

2021 ◽  
Vol 118 (35) ◽  
pp. e2104026118
Author(s):  
Han Cheng ◽  
Renjie Gui ◽  
Hao Yu ◽  
Chun Wang ◽  
Si Liu ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Oxygen Reduction ◽  
Intermetallic Compounds ◽  
Rational Design ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Average Particle ◽  
Size Limitation ◽  
Mass Activity

Pt-based alloy catalysts may promise considerable mass activity (MA) for oxygen reduction but are generally unsustainable over long-term cycles, particularly in practical proton exchange membrane fuel cells (PEMFCs). Herein, we report a series of Pt-based intermetallic compounds (Pt3Co, PtCo, and Pt3Ti) enclosed by ultrathin Pt skin with an average particle size down to about 2.3 nm, which deliver outstanding cyclic MA and durability for oxygen reduction. By breaking size limitation during ordered atomic transformation in Pt alloy systems, the MA and durability of subsize Pt-based intermetallic compounds can be simultaneously optimized. The subsize scale was also found to enhance the stability of the membrane electrode through preventing the poisoning of catalysts by ionomers in humid fuel-cell conditions. We anticipate that subsize Pt-based intermetallic compounds set a good example for the rational design of high-performance oxygen reduction electrocatalysts for PEMFCs. Furthermore, the prevention of ionomer poisoning was identified as the critical parameter for assembling robust commercial membrane electrodes in PEMFCs.

Highly durable electrocatalyst with low-loading platinum-cobalt nanoparticles dispersed over single-atom Co-N-Graphene nanofiber for efficient fuel cell

2021 ◽  
Author(s):  
Lina Chong ◽  
Jianguo Wen ◽  
Zhenzhen Yang ◽  
Yulin Lin ◽  
Ira Bloom ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Oxygen Reduction ◽  
Proton Exchange Membrane ◽  
Combustion Engine ◽  
Stress Test ◽  
Cost Effective ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Single Atom ◽  
Mass Activity

Abstract Development of highly-active, durable and cost-effective oxygen reduction electrocatalyst for proton exchange membrane fuel cell is crucial and greatly desired to enable fuel cell powered vehicles that are competitive with internal combustion engine automobiles. The support’s structure is known to strongly influence the performance of Pt particles. Here, we present a new catalyst containing PtCo core-shell nanoparticle supported over hierarchical tailored porous carbon nanofibers with densely populated single-atomic Co-Nx sites embedded in N-doped graphene. In a fuel cell with a total Pt loading (anode + cathode) of 0.091 mg cm-2, the new catalyst delivered unprecedented mass activity of 2.28 A mgPt-1 at 0.9 ViR-free, Pt utilization of 11.1 kW gPt-1 at 150 kPaabs, and high durability with 80% retention of initial mass activity after 30,000 accelerated-stress-test cycles, significantly higher than that of the state-of-the-art Pt3Co/C. In-situ X-ray absorption spectroscopy revealed structure reversibility of the catalyst during oxygen reduction reaction and indicated that the enhanced activity can be attributed to simultaneous PtCo and Co-Nx contributions.

scholarly journals Degradation and regeneration of Fe-Nx active sites for oxygen reduction reaction: the role of surface oxidation, Fe demetallation and local carbon microporosity

2021 ◽  
Author(s):  
Dongsheng Xia ◽  
Chenchen Yu ◽  
Yinghao Zhao ◽  
Yinping Wei ◽  
Haiyan Wu ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Active Sites ◽  
Proton Exchange Membrane ◽  
Degradation Mechanism ◽  
Surface Oxidation ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Exchange Membrane

The severe degradation of Fe-N-C electrocatalysts during long-term oxygen reduction reaction (ORR) has become a major obstacle for application in proton-exchange membrane fuel cells. Understanding the degradation mechanism and regeneration...

The development of a highly durable Fe-N-C electrocatalyst with favorable CNT structures for the oxygen reduction in PEMFCs

2021 ◽  
pp. 1-7
Author(s):  
Shuiyun Shen ◽  
Ziwen Ren ◽  
Silei Xiang ◽  
Shiqu Chen ◽  
Zehao Tan ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Oxygen Reduction ◽  
Proton Exchange Membrane ◽  
Metal Organic Framework ◽  
High Energy ◽  
Proton Exchange ◽  
Rotating Disk Electrode ◽  
High Energy Density ◽  
Pt Catalyst ◽  
Highly Active

Abstract Proton exchange membrane fuel cell (PEMFC) is a crucial route for energy saving, emission reduction and the development of new energy vehicles because of its high power density, high energy density as well as the low operating temperature which corresponds to fast starting and power matching. However, the rare and expensive Pt resource greatly hinders the mass production of fuel cell, and the development of highly active and durable non-precious metal catalysts toward the oxygen reduction reaction (ORR) in the cathode is considered to be the ultimate solution. In this article, a highly active and durable Fe-N-C catalyst was facilely derived from metal organic framework materials (MOFs), and a favorable structure of carbon nanotubes (CNTs) were formed, which accounts for a desired good durability. The as-optimized catalyst has a half-wave potential of 0.84V for the ORR, which is comparable to that of commercial Pt/C. More attractively, it has good stabilities both in rotating disk electrode and single cell tests, which provides a large practical application potential in the replacement of Pt catalyst as the ORR electrocatalyst in fuel cells.

scholarly journals MOF Derived Catalysts for Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cell

2018 ◽  
Vol 778 ◽  
pp. 275-282
Author(s):  
Noaman Khan ◽  
Saim Saher ◽  
Xuan Shi ◽  
Muhammad Noman ◽  
Mujahid Wasim Durani ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Membrane Electrode Assembly ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Nitrogen Doped ◽  
Nitrogen Doped Carbon ◽  
Exchange Membrane

Highly porous ZIF-67 (Zeolitic imidazole framework) has a conductive crystalline metal organic framework (MOF) structure which was served as a precursor and template for the preparation of nitrogen-doped carbon nanotubes (NCNTs) electrocatalysts. As a first step, the chloroplatinic acid, a platinum (Pt) precursor was infiltrated in ZIF-67 with a precise amount to obtain 0.12 mg.cm-2 Pt loading. Later, the infiltrated structure was calcined at 700°C in Ar:H2 (90:10 vol%) gas mixture. Multi-walled nitrogen-doped carbon nanotubes were grown on the surface of ZIF-67 crystals following thermal activation at 700°C. The resulting PtCo-NCNTs electrocatalysts were deposited on Nafion-212 solid electrolyte membrane by spray technique to study the oxygen reduction reaction (ORR) in the presence of H2/O2 gases in a temperature range of 50-70°C. The present study elucidates the performance of nitrogen-doped carbon nanotubes ORR electrocatalysts derived from ZIF-67 and the effects of membrane electrode assembly (MEA) steaming on the performance of proton exchange membrane fuel cell (PEMFC) employing PtCo-NCNTs as ORR electrocatalysts. We observed that the peak power density at 70°C was 450 mW/cm2 for steamed membrane electrode assembly (MEA) compared to 392 mW/cm2 for an identical MEA without steaming.

A Simplified Three-Dimensional CFD Approach for PEMFC and DMFC Design

2003 ◽  
Author(s):  
C. W. Hong ◽  
C. H. Cheng ◽  
K. Fei
Keyword(s):  
Transport Phenomenon ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Performance Test ◽  
Direct Methanol Fuel Cells ◽  
Proton Exchange ◽  
Design Tool ◽  
Cathode Side ◽  
Membrane Electrode ◽  
Crossover Effect

This paper describes the fundamental theory, algorithm and computation methods to predict the performance of proton exchange membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFC) using a simplified computational fluid dynamics (CFD) approach. Based on the common transport phenomenon inside both fuel cells, the mass, momentum, energy and species equations were derived. Darcy laws were employed to simplify the momentum equation and also to linearize the species equation. The mathematical model was solved in various flow channel designs and some membrane electrode assembly (MEA) options. The major concern is mainly on the cathode side, in the PEMFC case, that dominates the performance deterioration due to potential loss in the flow field. In the case of DMFCs, both anode and cathode sides are simulated. The methanol crossover effect is also included. This virtual performance test bench plays an important role in the prototype fuel cell design. The computer aided design tool is proved to be useful in configuration designs. Additionally, it provides the detailed transport phenomenon inside the fuel cell stack.

scholarly journals Recent Progress in the Development of Aromatic Polymer-Based Proton Exchange Membranes for Fuel Cell Applications

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1061 ◽  
Author(s):  
Raja Rafidah R. S. ◽  
Rashmi W. ◽  
Khalid M. ◽  
Wong W. Y. ◽  
Priyanka J.
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Proton Conductivity ◽  
Elevated Temperatures ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Polymer Chains ◽  
Membrane Electrode ◽  
Aryl Ether

Proton exchange membranes (PEMs) play a pivotal role in fuel cells; conducting protons from the anode to the cathode within the cell’s membrane electrode assembles (MEA) separates the reactant fuels and prevents electrons from passing through. High proton conductivity is the most important characteristic of the PEM, as this contributes to the performance and efficiency of the fuel cell. However, it is also important to take into account the membrane’s durability to ensure that it canmaintain itsperformance under the actual fuel cell’s operating conditions and serve a long lifetime. The current state-of-the-art Nafion membranes are limited due to their high cost, loss of conductivity at elevated temperatures due to dehydration, and fuel crossover. Alternatives to Nafion have become a well-researched topic in recent years. Aromatic-based membranes where the polymer chains are linked together by aromatic rings, alongside varying numbers of ether, ketone, or sulfone functionalities, imide, or benzimidazoles in their structures, are one of the alternatives that show great potential as PEMs due totheir electrochemical, mechanical, and thermal strengths. Membranes based on these polymers, such as poly(aryl ether ketones) (PAEKs) and polyimides (PIs), however, lack a sufficient level of proton conductivity and durability to be practical for use in fuel cells. Therefore, membrane modifications are necessary to overcome their drawbacks. This paper reviews the challenges associated with different types of aromatic-based PEMs, plus the recent approaches that have been adopted to enhance their properties and performance.

Multidimensional nanostructured membrane electrode assemblies for proton exchange membrane fuel cell applications

2019 ◽  
Vol 7 (16) ◽  
pp. 9447-9477 ◽  
Author(s):  
Guoliang Wang ◽  
Liangliang Zou ◽  
Qinghong Huang ◽  
Zhiqing Zou ◽  
Hui Yang
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Recent Progress ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Membrane Electrode Assemblies ◽  
Electrode Assemblies ◽  
Exchange Membrane

This review highlights the recent progress in multidimensional nanostructured membrane electrode assemblies for PEMFCs and DMFCs.

Investigation of Thermal Influence on the Assembly of Polymer Electrolyte Membrane Fuel Cell Stacks

2012 ◽  
Vol 512-515 ◽  
pp. 1509-1514
Author(s):  
Lin Fa Peng ◽  
Dian Kai Qiu ◽  
Pei Yun Yi ◽  
Xin Min Lai
Keyword(s):  
Thermal Expansion ◽  
Fuel Cell ◽  
Contact Pressure ◽  
Proton Exchange Membrane ◽  
Three Dimensional ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Fe Model ◽  
Assembly Process

The assembly force in a proton exchange membrane fuel cell (PEMFC) stack affects the characteristics of the porosity and electrical conductivity. Generally, the stack is assembled at room temperature while it’s operated at about 80 °Cor even higher. As a result, the assembly pressure can’t keep constant due to thermal expansion. This paper focuses on the contact pressure between membrane electrode assembly (MEA) and bipolar plates in real operations. A three-dimensional finite element (FE) model for the assembly process is established with coupled thermal-mechanical effects. The discipline of contact pressure under thermal-mechanical effect is investigated. A single cell stack is fabricated in house for the analysis of contact pressures on gas diffusion layer at different temperatures. The results show that as the temperature increases, contact pressure increases due to thermal expansion. It indicates that the influence of thermal expansion due to temperature variation should be taken into consideration for the design of the stack assembly process.

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