Study of electrochemiluminescence of lucigenin at glassy carbon electrodes in NaOH solution

Two cathodic electrochemiluminescence (ECL) pathways were firstly resolved at glassy carbon electrodes for alkaline lucigenin system by using the potential-resolved ECL method. The light emitters for the ECL emission were identified as excited N-methylacridone and excited lucigenin molecules according to the in situ UV–visible absorption spectra and the fluorescence spectra. Two mechanistic schemes are proposed: (1) the pathway for the ECL pre-peak at about −0.37 (versus Ag) is due to the electroreduction of lucigenin forming its radical cation at the electrode surface, which then reacts with dissolved oxygen in the solution to yield light emission; (2) the pathway of the major ECL peak at −0.50 V is due to the reaction of lucigenin with the electrogenerated H2O2.