K1003 Photoelectric electrochemical cell

1. The volume of the electrolytic cell, the oxygen reduction reaction (ORR) needs to provide a good liquid laminar flow state,

Thereby obtaining a uniform current distribution. From the analysis of the liquid phase mass transfer process, the dissolution away from the electrode surface

In the liquid, convection is the main mass transfer process, and the mass transfer in the solution layer near the electrode surface is mainly dependent on the

By diffusion process. However, it is very difficult to distinguish the two mass transfer processes strictly in general.

There is always a region of space where the two mass transfer methods interact. Therefore, in order to eliminate both

The influence of the shift can separate the diffusion mass transfer zone and the convection mass transfer zone, requiring a relatively small volume of electrolyte.

Large, thus requiring a large volume electrolytic cell. When the rotating disk electrode rotates, it can be thought of as

The electrolyte concentration at each position in the bath is uniform. At the same time, choose a larger electrolytic cell and rotate

The disk electrode is far enough away from the cell wall of the electrolysis cell and the flow and movement of the electrode is not affected by the cell wall, often

It is advisable to use an electrolytic cell volume of 150 mL, and if the volume is too small (eg 50-100 mL), the result of the experiment will be

Adversely affected.

2. The geometry of the electrolytic cell and the equivalent circuit of the electrochemical cell are shown in Fig. 1. Ru is a worker.

As the resistance between the electrode and the reference electrode solution, the smaller the distance between the working electrode and the reference electrode, the greater the resistance

Small, Piontelli has systematically studied the effect of the reference electrode placement on the electrochemical test results.

It shows that when the reference electrode is directly below the working electrode and the open top of the reference electrode is close to the operating power

At the extreme, the test is best. However, the design of this placement is not practical in the actual operation.

Because when the rotating disk's working electrode rotates, it will generate friction with the reference electrode, which will result in laminar flow.

The state caused great disturbances. Barnartt study shows that when the distance between the working electrode and the end of the reference electrode is

The test effect is best when it is four times the radius of the electrode (ie about 5mm). At this distance, due to electrolysis

The low conductivity of the material or the IR drop produced at high current densities can be corrected. Current electrolytic cell often

As seen in Figure 2, the electrolytic cell not only satisfies the larger volume (150 mL) of the electrolytic cell,

At the same time, its geometry also satisfies the most suitable distance between the working electrode and the reference electrode (fixed socket position),

This reduces the effect of the internal resistance of the solution on the experimental results.

In summary, during the oxygen reduction reaction (ORR) process, at least the choice of electrolytic cell needs to be considered.

Its volume and geometry are two aspects. Other electrochemical reactions such as OER, hydrogen evolution

It should also follow this principle.