3 The Measurements of the Oxygen Reduction Reaction
57
The results showed that different concentrations of sodium perchlorate were added
to 0.1 mol·L
−1 HClO 4 , and the oxygen reduction mass activity of the commercial
Pt/C catalyst was worse than that without time. Moreover, when the concentration of
sodium perchlorate added was 1 mol·L
−1 . The oxygen reduction of the commercial
Pt/C catalyst has a negative shift of about 30 mV, and the kinetics of oxygen reduction
was hindered. It is indicated that reducing the resistance of the solution by introducing
a strong electrolyte salt will affect the test results, and the high concentration of salt
will hinder the correct characterization of the oxygen reduction performance of the
catalyst. The current possible explanation is that increasing the concentration of
salt actually increases the concentration of ions. On the one hand, these ions affect
the mass transfer of oxygen on the one hand, and may adsorb on the surface of
the electrode on the other hand, affecting the adsorption and reduction of oxygen,
and finally, the data that led to the measurement of oxygen reduction performance
deteriorated, which is why the conventional oxygen reduction test was carried out in
0.1 mol·L
−1 HClO 4 . The following section will discuss in detail the other important
factors affecting the oxygen reduction test.
3.3.4 Electrode Film-Forming Technology
In the rotating disk electrode test, the film formation quality and film formation
uniformity of the electrode will greatly affect the oxygen reduction activity of the
catalyst.
There are two ways to dry the catalyst film. One is the static drying method, that
is, the dispersed catalyst slurry is dropped on the surface of the electrode, and then
dried in the air or by other auxiliary drying means in a static state, thereby rotating
the circle. A uniform film is obtained on the surface of the disk electrode; the other
method is a spin-drying method, that is, the dispersed catalyst slurry is dropped on
the surface of the electrode, and then the electrode is dried at a certain rotation speed
to obtain a catalyst with uniform adhesion film.
3.3.4.1 Static Drying Method
Figure 3.9 is a catalyst film obtained by a static drying method, here taking 19.7%
of a Pt/C catalyst as an example (E-TECK). It can be seen from the figure that the
catalyst film obtained by the static drying method has the following problems: (1) the
film-forming quality of the edge portion of the catalyst film is relatively uniform, and
the film quality of the intermediate portion is poor; (2) the center of the electrode is
formed. The film thickness is thin, and the edge portion is not completely formed, and
the electrode is not completely covered; (3) the film-forming quality of the electrode
surface is uniform, but the edge portion is preferentially dried due to faster diffusion,
and the center portion of the electrode is finally dried, if when the obtained catalyst
57
The results showed that different concentrations of sodium perchlorate were added
to 0.1 mol·L
−1 HClO 4 , and the oxygen reduction mass activity of the commercial
Pt/C catalyst was worse than that without time. Moreover, when the concentration of
sodium perchlorate added was 1 mol·L
−1 . The oxygen reduction of the commercial
Pt/C catalyst has a negative shift of about 30 mV, and the kinetics of oxygen reduction
was hindered. It is indicated that reducing the resistance of the solution by introducing
a strong electrolyte salt will affect the test results, and the high concentration of salt
will hinder the correct characterization of the oxygen reduction performance of the
catalyst. The current possible explanation is that increasing the concentration of
salt actually increases the concentration of ions. On the one hand, these ions affect
the mass transfer of oxygen on the one hand, and may adsorb on the surface of
the electrode on the other hand, affecting the adsorption and reduction of oxygen,
and finally, the data that led to the measurement of oxygen reduction performance
deteriorated, which is why the conventional oxygen reduction test was carried out in
0.1 mol·L
−1 HClO 4 . The following section will discuss in detail the other important
factors affecting the oxygen reduction test.
3.3.4 Electrode Film-Forming Technology
In the rotating disk electrode test, the film formation quality and film formation
uniformity of the electrode will greatly affect the oxygen reduction activity of the
catalyst.
There are two ways to dry the catalyst film. One is the static drying method, that
is, the dispersed catalyst slurry is dropped on the surface of the electrode, and then
dried in the air or by other auxiliary drying means in a static state, thereby rotating
the circle. A uniform film is obtained on the surface of the disk electrode; the other
method is a spin-drying method, that is, the dispersed catalyst slurry is dropped on
the surface of the electrode, and then the electrode is dried at a certain rotation speed
to obtain a catalyst with uniform adhesion film.
3.3.4.1 Static Drying Method
Figure 3.9 is a catalyst film obtained by a static drying method, here taking 19.7%
of a Pt/C catalyst as an example (E-TECK). It can be seen from the figure that the
catalyst film obtained by the static drying method has the following problems: (1) the
film-forming quality of the edge portion of the catalyst film is relatively uniform, and
the film quality of the intermediate portion is poor; (2) the center of the electrode is
formed. The film thickness is thin, and the edge portion is not completely formed, and
the electrode is not completely covered; (3) the film-forming quality of the electrode
surface is uniform, but the edge portion is preferentially dried due to faster diffusion,
and the center portion of the electrode is finally dried, if when the obtained catalyst