Carbon-supported Platinum Electrocatalysts probed in a Gas Diffusion Setup with Alkaline Environment: how Particle Size and Mesoscopic Environment influence the Degradation Mechanism

2020 ◽  
Author(s):  
Shima Alinejad ◽  
Jonathan Quinson ◽  
Johanna Schröder ◽  
Jacob J. K. Kirkensgaard ◽  
Matthias Arenz
Keyword(s):  
Particle Size ◽  
Degradation Mechanism ◽  
Active Phase ◽  
Active Surface ◽  
Carbon Support ◽  
Gas Diffusion ◽  
Active Surface Area ◽  
Electrochemical Cells ◽  
Co Stripping ◽  
Large Particles

In this work, we investigate the stability of four different types of Pt/C fuel cell catalysts upon applying accelerated degradation tests (ADTs) in a gas diffusion electrode (GDE) setup equipped with an anion exchange membrane (AEM). In contrast to previous investigations exposing the catalysts to liquid electrolyte, the GDE setup provides a realistic three-phase boundary of the reactant gas, catalyst and ionomer which enables reactant transport rates close to real fuel cells. Therefore, the GDE setup mimics the degradation of the catalyst under more realistic reaction conditions as compared to conventional electrochemical cells. Combining the determination of the loss in electrochemically active surface area (ECSA) of the Pt/C catalysts via CO stripping measurements with the change in particle size distribution determined by small-angle X-ray scattering (SAXS) measurements, we demonstrate that i) the degradation mechanism depends on the investigated Pt/C catalyst and might indeed be different to the one observed in conventional electrochemical cells, ii) degradation is increased in an oxygen gas atmosphere (as compared to an inert atmosphere), and iii) the observed degradation mechanism depends on the mesoscopic environment of the active phase. The measurements indicate an increased particle growth if small and large particles are immobilized next to each other on the same carbon support flakes as compared to a simple mix of two catalysts with small and large particles, respectively.

scholarly journals Carbon-supported Platinum Electrocatalysts probed in a Gas Diffusion Setup with Alkaline Environment: how Particle Size and Mesoscopic Environment influence the Degradation Mechanism

2020 ◽  
Author(s):  
Shima Alinejad ◽  
Jonathan Quinson ◽  
Johanna Schröder ◽  
Jacob J. K. Kirkensgaard ◽  
Matthias Arenz
Keyword(s):  
Particle Size ◽  
Degradation Mechanism ◽  
Active Phase ◽  
Active Surface ◽  
Carbon Support ◽  
Gas Diffusion ◽  
Active Surface Area ◽  
Electrochemical Cells ◽  
Co Stripping ◽  
Large Particles

In this work, we investigate the stability of four different types of Pt/C fuel cell catalysts upon applying accelerated degradation tests (ADTs) in a gas diffusion electrode (GDE) setup equipped with an anion exchange membrane (AEM). In contrast to previous investigations exposing the catalysts to liquid electrolyte, the GDE setup provides a realistic three-phase boundary of the reactant gas, catalyst and ionomer which enables reactant transport rates close to real fuel cells. Therefore, the GDE setup mimics the degradation of the catalyst under more realistic reaction conditions as compared to conventional electrochemical cells. Combining the determination of the loss in electrochemically active surface area (ECSA) of the Pt/C catalysts via CO stripping measurements with the change in particle size distribution determined by small-angle X-ray scattering (SAXS) measurements, we demonstrate that i) the degradation mechanism depends on the investigated Pt/C catalyst and might indeed be different to the one observed in conventional electrochemical cells, ii) degradation is increased in an oxygen gas atmosphere (as compared to an inert atmosphere), and iii) the observed degradation mechanism depends on the mesoscopic environment of the active phase. The measurements indicate an increased particle growth if small and large particles are immobilized next to each other on the same carbon support flakes as compared to a simple mix of two catalysts with small and large particles, respectively.

Carbon-supported Platinum Electrocatalysts probed in a Gas Diffusion Setup with Alkaline Environment: how Particle Size and Mesoscopic Environment influence the Degradation Mechanism

2020 ◽  
Author(s):  
Shima Alinejad ◽  
Jonathan Quinson ◽  
Johanna Schröder ◽  
Jacob J. K. Kirkensgaard ◽  
Matthias Arenz
Keyword(s):  
Particle Size ◽  
Degradation Mechanism ◽  
Active Phase ◽  
Active Surface ◽  
Carbon Support ◽  
Gas Diffusion ◽  
Active Surface Area ◽  
Electrochemical Cells ◽  
Co Stripping ◽  
Large Particles

In this work, we investigate the stability of four different types of Pt/C fuel cell catalysts upon applying accelerated degradation tests (ADTs) in a gas diffusion electrode (GDE) setup equipped with an anion exchange membrane (AEM). In contrast to previous investigations exposing the catalysts to liquid electrolyte, the GDE setup provides a realistic three-phase boundary of the reactant gas, catalyst and ionomer which enables reactant transport rates close to real fuel cells. Therefore, the GDE setup mimics the degradation of the catalyst under more realistic reaction conditions as compared to conventional electrochemical cells. Combining the determination of the loss in electrochemically active surface area (ECSA) of the Pt/C catalysts via CO stripping measurements with the change in particle size distribution determined by small-angle X-ray scattering (SAXS) measurements, we demonstrate that i) the degradation mechanism depends on the investigated Pt/C catalyst and might indeed be different to the one observed in conventional electrochemical cells, ii) degradation is increased in an oxygen gas atmosphere (as compared to an inert atmosphere), and iii) the observed degradation mechanism depends on the mesoscopic environment of the active phase. The measurements indicate an increased particle growth if small and large particles are immobilized next to each other on the same carbon support flakes as compared to a simple mix of two catalysts with small and large particles, respectively.

scholarly journals Preparation and Electrocatalytic Characteristics Research of Pd/C Catalyst for Direct Ethanol Fuel Cell

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Qiao Xia Li ◽  
Ming Shuang Liu ◽  
Qun Jie Xu ◽  
Hong Min Mao
Keyword(s):  
Fuel Cell ◽  
Average Particle Size ◽  
Active Surface ◽  
Carbon Support ◽  
Catalytic Performance ◽  
Active Surface Area ◽  
Average Particle ◽  
Ethanol Fuel ◽  
Direct Ethanol Fuel Cell ◽  
Electrochemical Active Surface Area

Two kinds of carbon-support 20% Pd/C catalysts for use in direct ethanol fuel cell (DEFC) have been prepared by an impregnation reduction method using NaBH4and NaH2PO2as reductants, respectively, in this study. The catalysts were characterized by XRD and TEM. The results show that the catalysts had been completely reduced, and the catalysts are spherical and homogeneously dispersed on carbon. The electrocatalytic activity of the catalysts was investigated by electrochemical measurements. The results indicate that the catalysts had an average particle size of 3.3 nm and showed the better catalytic performance, when NaBH4was used as the reducing agent. The electrochemical active surface area of Pd/C (NaBH4) was 56.4 m2·g−1. The electrochemical activity of the Pd/C (NaBH4) was much higher than that of Pd/C (NaH2PO2).

Influence of Manufacturing Parameters on MEA and PEMFC Performance

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Aránzazu Barrio ◽  
Javier Parrondo ◽  
Jose Ignacio Lombraña ◽  
Maria Uresandi ◽  
Federico Mijangos
Keyword(s):  
Proton Exchange Membrane ◽  
Linear Sweep Voltammetry ◽  
Active Surface ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Point Of View ◽  
Active Surface Area ◽  
Alternative Power ◽  
Operational Range ◽  
Exchange Membrane

Proton-exchange membrane fuel cells (PEMFC) are regarded as a possible alternative power source for stationary and mobile applications. Due to the catalyst costs, many researchers have been studying the membrane and the electrode assembly (MEA) manufacturing processes that can reduce the content of Pt in the electrocatalyst layer while maintaining the performance. The MEA is the heart of the PEMFC and the catalyst plays an important role in the fuel cell operation.There are different methods to prepare MEA. In this work, the catalyst ink was straightly applied on the gas diffusion layer (GDL) by an aerograph. Then, this electrode was assembled to the membrane by hot press.From the point of view of operation, the main variables are: temperature, pressure and time of press. Operational range was established from previous experiments to find roughly the optimal conditions. Finally, these MEAs were tested in a 5 cm2 PEMFC. The operational temperature was 30°C. Due to higher temperatures it was difficult to keep the humidity of the membrane constant. The operational pressure and flow were constant throughout the experiments. Different techniques to characterize the MEAs, linear sweep voltammetry and cyclic voltammetry were applied. With these techniques the permeation of hydrogen and the electrochemically active surface area of electrode catalyst were determined.With the results obtained in the experiments, the optimal values of the fabrication parameters were established.

scholarly journals Improving Catalytic Activity in the Electrochemical Separation of CO2 Using Membrane Electrode Assemblies

2022 ◽  
Author(s):  
Nicholas Schwartz ◽  
Jason Harrington ◽  
Kirk J Ziegler ◽  
Philip Cox
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Catalytic Activity ◽  
Electrochemical Impedance ◽  
Gas Diffusion ◽  
Rotating Disk Electrode ◽  
Constant Current ◽  
Membrane Electrode ◽  
Active Surface Area ◽  
Separation Of Co2

Abstract The direct electrochemically driven separation of CO2 from a humidified N2, O2, and CO2 gas mixture was conducted using an asymmetric membrane electrode assembly (MEA). The MEA was fabricated using a screen-printed ionomer bound Pt cathode, an anion exchange membrane (AEM), and ionomer bound IrO2 anode. Electrocatalyst materials were physically and chemically characterized prior to inclusion within the electrode. Electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) measurements using a rotating disk electrode (RDE) were used to quantify the catalytic activity and determine the effects of the catalyst-to-ionomer ratio. Catalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface analysis, and (dynamic light scattering) DLS to evaluate catalyst structure, active surface area, and determine the particle size and bulk particle size distribution (PSD). The electrocatalyst layer of the electrodes were fabricated by screen printing a uniformly dispersed mixture of catalyst, dissolved anionic ionomer, and a solvent system onto an electrode supporting gas diffusion layer (GDL). Pt IrO2 MEAs were fabricated and current-voltage relationships were determined using constant-current measurements over a range of applied current densities and flow rates. Baseline reaction kinetics for CO2 separation were established with a standard set of Pt-IrO2 MEAs.

Graphene Role as Platinum Support for CO and Formic Acid Electrooxidation

2011 ◽  
Vol 1326 ◽  
Author(s):  
Shirui Guo ◽  
Huseyin Sarialtin ◽  
Shaun Alia ◽  
Hayri Engin Akin ◽  
Yushan Yan ◽  
...  
Keyword(s):  
Particle Size ◽  
Fuel Cell ◽  
Formic Acid ◽  
High Efficiency ◽  
Chemical Reduction ◽  
Pt Nanoparticles ◽  
Active Surface ◽  
Active Surface Area ◽  
Support Materials ◽  
Loading Amount

AbstractThe direct methanol fuel cell (DMFC) is a promising power source for electronic applications due to its high efficiency and compactness. To improve the efficiency, many support materials have been developed. We investigated uniform graphene nanoflake films as a support for catalytic Pt nanoparticles in direct carbon monooxide and formic acid electro-oxidation. Pt nanoparticles were deposited on the surface of graphene films with chemical reduction method. Chemical functionalization of graphene with ethylenediamine enables Pt nanoparticles mobilize on graphene uniformly. By simply changing the loading amount of Pt precursor, various particle sizes were achieved. The particle size of Pt plays prominent role in fuel cell test. The electrochemically active surface area of different sample are 6.3 (5 wt% Pt/G), 4.1 (20 wt% Pt/G), and 3.0 (50 wt% Pt/G) cm2mg-1 corresponding to the particle size 3±1nm, 10±2nm, 20±2nm respectively. The results obtained are ascribed to a uniform network made of 2-4 nm Pt monolayer nanopaticles on the surface of graphene flakes. Graphene will play significant role in developing next-generation advanced Pt based fuel cells and their relevant electrodes in the field of energy.

scholarly journals PAC Synthesis and Comparison of Catalysts for Direct Ethanol Fuel Cells

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 712
Author(s):  
Alexandra Kuriganova ◽  
Daria Chernysheva ◽  
Nikita Faddeev ◽  
Igor Leontyev ◽  
Nina Smirnova ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Supported Catalysts ◽  
Active Surface ◽  
Carbon Surface ◽  
Active Surface Area ◽  
Ethanol Fuel ◽  
Direct Ethanol Fuel Cells ◽  
Onset Potential ◽  
Co Stripping ◽  
Pac Technique

Pt/C, PtMOn/C (M = Ni, Sn, Ti, and PtX/C (X = Rh, Ir) catalyst systems were prepared by using the pulse alternating current (PAC) technique. Physical and electrochemical parameters of samples were carried out by x-ray powder diffraction (XRD), transmission electron microscopy (TEM), and CO stripping. The catalytic activity of the synthesized samples for the ethanol electrooxidation reaction (EOR) was investigated. The XRD patterns of the samples showed the presence of diffraction peaks characteristic for Pt, NiO, SnO2, TiO2, Rh, and Ir. The TEM images indicate that the Pt, Rh, and PtIr (alloys) particles had a uniform distribution over the carbon surface in the Pt/C, PtRh/C, PtIr/C, and PtMOn/C (M = Ni, Sn, Ti) catalysts. The electrochemically active surface area of catalysts was determined by the CO-stripping method. The addition of a second element to Pt or the use of hybrid supported catalysts can evidently improve the EOR activity. A remarkable positive affecting shift of the onset potential for the EOR was observed as follows: PtSnO2/C > PtTiO2/C ≈ PtIr/C ≈ PtNiO/C > PtRh/C ≈ Pt/C. The addition of SnO2 to Pt/C catalyst led to the decrease of the onset potential and to significantly facilitate the EOR. The long-term cyclic stability of the synthesized catalysts was investigated. Thereby, the PtSnO2/C catalyst prepared by the PAC technique can be considered as a promising anode catalyst for direct ethanol fuel cells.

scholarly journals Surfactant-Assisted Sol-Gel Synthesis of TiO2 with Uniform Particle Size Distribution

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
O. L. Galkina ◽  
V. V. Vinogradov ◽  
A. V. Agafonov ◽  
A. V. Vinogradov
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Sol Gel ◽  
Active Surface ◽  
Titanium Isopropoxide ◽  
Active Surface Area ◽  
Vis Spectroscopy ◽  
Uniform Particle Size ◽  
Surfactant Assisted

TiO2 materials were prepared from a titanium isopropoxide precursor by sol-gel processing in water media with or without various templates (polyethylenimine or Pluronic P-123). The photocatalytic efficiency of the samples was found to depend strongly on the use of and type of template added. Titania/Pluronic sols resulted in homogeneous anatase TiO2—rutile with uniform particle size distribution after calcination (400°C). Optical properties of the samples were characterized by UV-Vis spectroscopy and crystalline structures by X-ray diffraction. A surfactant-assisted sol-gel process retarded crystallization of the anatase and rutile titania, which resulted in smaller grain sizes and presumably a larger active surface area. The morphology of the surfaces was obtained by AFM techniques. The highest photobleaching rate was found for samples deposited from the sol with the addition of the Pluronic P-123 surfactant, and it was almost twice as high as that for films deposited from sols with polyethylenimine.

scholarly journals Effects of Environmental Conditions on Cathode Degradation of Polymer Electrolyte Fuel Cell during Potential Cycle

2019 ◽  
Vol 10 (2) ◽  
pp. 24
Author(s):  
Yoshiyuki Hashimasa ◽  
Hiroshi Daitoku ◽  
Tomoaki Numata
Keyword(s):  
Fuel Cell ◽  
Active Surface ◽  
Carbon Support ◽  
Load Cycle ◽  
Polymer Electrolyte Fuel Cell ◽  
Active Surface Area ◽  
Test Protocol ◽  
Carbon Corrosion ◽  
Durability Test ◽  
Cathode Degradation

We investigated the effects of cell temperature and the humidity of gas supplied to the cell during the load cycle durability test protocol recommended by The Fuel Cell Commercialization Conference of Japan (FCCJ). Changes in the electrochemically active surface area (ECA) and in the amount of carbon support corrosion were examined by using the JARI standard single cell. The ECA declined more quickly when the gas humidity was raised, and the carbon corrosion was at the same level. These results suggest that the agglomeration of platinum was accelerated by the same agglomeration mechanism, i.e., by raising the humidity of the gas supplied to the cell.

Effects of Freezing and Thawing on the Structures of Porous Gas Diffusion Media

2007 ◽  
Author(s):  
Joaquin A. Pelaez ◽  
Satish G. Kandlikar
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Active Surface ◽  
Membrane Electrode Assembly ◽  
Gas Diffusion ◽  
Membrane Electrode ◽  
Active Surface Area ◽  
Freezing And Thawing ◽  
Diffusion Media ◽  
Cell Components

Fuel cells are a very promising technology for transportation applications in the future. Many companies are performing research in order to make the implementation of fuel cell-powered vehicles more feasible. One issue that needs to be addressed is the fact that fuel cell vehicles will be used in sub-freezing climates. Vehicles undergo frequent shut down and startup events, and as such, freezing and thawing effects on fuel cell components become important when the vehicle is stored overnight in cold climates. When shut off, fuel cells will maintain water in the membrane electrode assembly (MEA) and gas diffusion media unless certain purging protocols are adhered to. When the cell is subjected to sub-freezing temperatures, the water remaining in these media will freeze. This freezing could have a detrimental impact on the pore structure, fiber integrity, and binder effectiveness in the GDL, thereby decreasing the electrochemical active surface area of the electrolytes and hurting the overall performance of the cell. This paper details the prior research in the area of freezing and thawing effects in these media and also details current research on the degradation of the GDL specifically.

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