A new electrogenerated chemiluminescence peak of lucigenin in the hydrogen-evolution region induced by platinum nanoparticles

The electrogenerated chemiluminescence (ECL) behavior of lucigenin at a glassy carbon electrode in the presence of platinum nanoparticles dispersed in alkaline aqueous solutions was studied under conventional cyclic voltammetry (CV). Two ECL peaks were observed at -0.65 and -2.0 V (vs SCE), respectively. ECL-1 was a conventional ECL peak of lucigenin also observed in the absence of platinum nanoparticles. ECL-2 was a new ECL peak appearing in the hydrogen-evolution potential region. It was found that ECL-1 decreased and ECL-2 increased with an increase in the concentration of platinum nanoparticles. The ECL properties under various conditions were studied. It has been proposed that ECL-2 is likely due to that reductive intermediate HadsPt0 formed during the hydrogen-evolution process that reduced lucigenin cation (Luc(2+)) to monocation radial (Luc(.+)); Luc(.+) and HadsPt0 reacted with dissolved oxygen to generate O2(.-), which interacted with Luc(.+) to produce the excited state N-methylacridone (NMA), giving rise to light emission at 495 nm. Pt nanoparticles synthesized in various methods showed different catalysis abilities for ECL-2. Furthermore, palladium particles similar to platinum particles can also catalyze the generation of ECL-2 while gold particles can not.