Working electrode: take the measurement of the reaction polarization curve on the copper electrode as an example, the working electrode (that is, the research electrode) is the place where the hydrogen evolution reaction occurs. Reference electrode: used as a reference to measure the overpotential of other electrodes.

Auxiliary electrode: Used to polarize the study electrode through a current. When studying the cathode process, the auxiliary electrode acts as the anode; when studying the anode process, the auxiliary electrode acts as the cathode.