Multichannel Electrochemiluminescence of\nLuminol in Neutral and Alkaline Aqueous Solutions\non a Gold Nanoparticle Self-Assembled Electrode

Abstract

The electrochemiluminescence (ECL) behavior of luminol\non a gold nanoparticle self-assembled electrode in neutral\nand alkaline pH conditions was studied under conventional cyclic voltammetry (CV). The gold nanoparticle self-assembled electrode exhibitied excellent electrocatalytic\nproperty and redox reactivity to the luminol ECL system.\nIn neutral solution, four ECL peaks were observed at\n0.69, 1.03, −0.45, and −1.22 V (vs SCE) on the curve\nof ECL intensity versus potential. Compared with a bulk\ngold electrode, two anodic and one cathodic ECL peaks\nwere greatly enhanced, and one new cathodic ECL peak\nappeared. In alkaline solution, two anodic ECL peaks\nwere obtained at 0.69 and 1.03 V, which were much\nstronger than those on a bulk gold electrode. These ECL\npeaks were found to depend on gold nanoparticles on the\nsurface of the electrode, potential scan direction and\nrange, the presence of O₂ or N₂, the pH and concentration\nof luminol solution, NaBr concentration, and scan rate.\nThe emitter of all ECL peaks was identified as 3-aminophthalate by analyzing the ECL spectra. The spatial\ndistribution of the luminol ECL peaks on the gold nanoparticle self-assembled electrode was studied by CCD. The\nsurface state of the gold nanoparticle self-assembled\nelectrode was characterized by scanning electron microscopy (SEM) and UV−visible reflection spectra. The mechanism for the formation of these ECL peaks has been\nproposed. The results indicate that the gold nanoparticle\nself-assembled electrode could lead to novel ECL properties, and strong luminol ECL in neutral and alkaline\nsolutions could be obtained on such an electrode, which\nis of great analytical potential.