Rotating Platinum Electrode (RPE)

• The Rotating Platinum Electrode (RPE) is used in electrochemical experiments, especially in rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) configurations.
• It provides enhanced mass transport for studying redox reactions, kinetics, and mass transfer.

Construction of Rotating Platinum Electrode:

1. Platinum Disk:

   • A flat, polished platinum disk (1-10 mm in diameter) mounted on insulating material like glass or Teflon.

2. Electrode Shaft:

   • The platinum disk is attached to a cylindrical shaft made from an insulating material, which connects the disk to the rotation mechanism and facilitates electrical connections.

3. Electrical Connection:

   • A conductive wire runs through the electrode shaft, establishing electrical contact between the potentiostat and the platinum disk.

4. Rotating Mechanism:

   • The electrode is connected to a motor or rotating device that controls rotation speed, crucial for controlling mass transport during the experiment.

Working of Rotating Platinum Electrode:

1. Electrode Immersion:

   • The platinum disk is immersed in the electrolyte solution containing the analyte, along with a reference and counter electrode.

2. Rotation:

   • The electrode is rotated at a controlled speed, generating centrifugal force that enhances mass transport to the electrode surface. At higher speeds, convection dominates mass transport.

3. Electrochemical Measurement:

   • The potentiostat applies a potential, causing redox reactions of the analyte at the platinum surface. The resulting current is proportional to the analyte concentration and reaction rate.

4. Data Analysis:

   • The current-potential data is analyzed to determine the analyte’s electrochemical behavior, such as redox potential, reaction kinetics, and concentration.

Advantages:

• Enhanced mass transport.
• Minimized concentration gradients.
• Suitable for studying fast electrode kinetics.

Limitations:

• Not ideal for analytes that form passivating layers on platinum.
• Limited applicability for species with low affinity for platinum.

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