The mechanism of the cobalt(II)-catalyzed electro-generated chemiluminescence of luminol in aqueous alkaline solution

A rotating ring—disc electrode system is used where the disc electrode (carbon) is maintained at a negative potential to reduce oxygen to hydrogen peroxide, and a symmetric double-step potential is applied to the ring electrode (platinum). Cobalt(II) catalyzes the electrogenerated chemiluminescence of luminol at the ring electrode during the negative pulse of the double-step potential. A possible reaction scheme for this cobalt(II)-catalyzed emission process is outlined.