Detection of hydrogen peroxide with luminol electrogenerated chemiluminescence at mesoporous platinum electrode in neutral aqueous solution

Electrogenerated chemiluminescence (ECL) behavior of luminol on a mesoporous platinum (H₁-ePt) electrode has been studied in a neutral aqueous solution of phosphate buffer at pH 7. ECL behavior of luminol on a mesoporous Pt electrode was quite different from that observed on a bare Pt electrode. Since the highly enlarged surface area of Pt electrode (roughness factor = 220) exhibited much larger electrochemical response for reductions of PtO and molecular oxygen, strong luminol ECL responses related to those electrochemical reactions were observed at ca. +0.1 V and -0.5 V vs. Ag/AgCl (3 M NaCl) even in a neutral solution pH. The presence of hydrogen peroxide led to further increase in the luminol ECL response. Under the optimum conditions, the ECL response of luminol was linear with the concentration of hydrogen peroxide in the range of 10^-8-10^-3-M with a detection limit of 2.62 nM (S/N = 3). The reproducibility of the ECL measurements for 1.0 mM hydrogen peroxide was quite good (relative standard deviation = 3.4%, n = 10).