Polymer Electrolyte Fuel Cells (PEFC)
Evaluation of Initial Properties of Catalysts


Example of analysis

Using two types of commercially available carbon-supported platinum (Pt) catalysts, an evaluation was made of their initial properties, including their basic properties such as the dispersed conditions and crystallinity of Pt, composition and surface area, and their activity.

【Dispersed conditions of Pt (TEM image)】

Catalyst A

Catalyst B

* Black particles represent Pt, and gray parts, carbon.

【Crystallinity of Pt particles (TEM image)】

Catalyst A

Catalyst B

Observation with the transmission electron microscope indicates that the Pt particles of Catalyst A are smaller than the ones of Catalyst B.

【Basic properties and activity】

Results of various analyses (table below) indicate that although Catalyst B has a smaller surface area than Catalyst A, Catalyst B shows higher activity.

Evaluation item Unit Catalyst A Catalyst B Evaluation method
Composition Pt wt% 46.3 44.0 (CP-AES high frequency plasma emission analysis)
45.2 44.6 CHN element analysis
0.3 <0.3
1.3 1.8
7.6 7.8 Enzymatic analysis
Surface area whole m²/g-cat. 310 90 N2 adsorption (BET method)
Pt m²/g-Pt 61 52 Cyclic voltammetry (CV)
Activity Reaction current mA @0.8V,400rpm 0.16 0.19 Hydrodynamic voltammetry (HDV)
No. of reaction electrons - @0.8V 2.9 3.4
Activation control current mA @0.8V 0.28 0.33
  • The larger the values of reaction current, number of reaction electrons and activation control current are, the higher the activity ( oxygen reduction performance) is.
  • Reaction current: Since the value of reaction current varies with test conditions, evaluation has to be performed under conditions close to actual use conditions.
  • Number of reaction electrons: This reflects the oxygen reduction reaction mechanism (4 electrons reduced, 2 electrons reduced, etc.)
  • Activation control current: This can be used as an index showing inherent activity of a catalyst that does not depend on test conditions (oxygen diffusion).

* The values of N2 adsorption method (BET method) are inspection values of the catalyst manufacturer.

Search Number 4024

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