Electrochemiluminescence (ECL) of 0.01 M luminol in NaOH medium of pH 12.0 on a boron-doped diamond (BDD) thin-film anode was studied in the absence and presence of H 2O 2. Here we show a new characteristic property of BDD allowing light emission in a wide potential range of 0.5-5.0 V vs Ag|AgCl, KCl(sat.), a behavior not observed for other anodes. Maximum ECL intensity was found at 2.2-2.8 V without H 2O 2, which became 63 times more intense after adding 0.05 M H 2O 2. The strong enhancement of ECL in the presence of H 2O 2 is attributed to the larger production of emitter 3-aminophthalate dianion, formed by selective nucleophilic attack of superoxide radical anion (O 2 ·-) to the radical electrogenerated from one-electron oxidation of the monoanionic form of luminol. Linear sweep voltammetry showed that ·OH was not generated from OH - oxidation, whereas O 2 ·- can be produced from HO 2 - oxidation. The performance of O 2 ·- in ECL was confirmed by p-benzoquinone quenching.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films