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:
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:
1) Electrode immersion:
The platinum disk is immersed in the electrolyte solution containing the analyte of interest, along with a reference electrode and a 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.