Electrochemiluminescence of Luminol on a Platinum-Nanoparticle-Modified Indium Tin Oxide Electrode in Neutral Aqueous Solution

Electrochemiluminescence (ECL) behavior of luminol on an indium tin oxide (ITO) electrode modified with platinum nanoparticles (PtNPs) was investigated in a neutral aqueous solution using the conventional cyclic voltammetry (CV) technique. Experimental results indicated that the ECL behaviors of luminol on the PtNPs modified electrode showed significant difference from those on the bare ITO or bulk platinum electrodes. Five ECL peaks were found at 0.60, 0.92, 0.70, -0.44 and -1.16 V versus a saturated calomel electrode (SCE), respectively. The ECL peaks were found to depend on the reaction medium conditions including the type of electrolyte, pH value, the presence or absence of 02 and the different kinds of nanoparticles, as well as the scan direction and range of the applied potential. Furthermore, ECL peaks at -0.44 and -1.16 V could only be obtained on the PtNPs/ITO electrode. The surface state of the electrode was characterized by ultraviolet-visible (UV-Vis) absorption, scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). A mechanism for luminol ECL on the PtNPs/ITO electrode was proposed. The excellent ECL properties of luminol on the PtNPs/ITO electrode in the neutral medium revealed a great potential for analytical applications to biological samples.