Intensification of the electrochemiluminescence of luminol on hollow TiO2 nanoshell-modified indium tin oxide electrodes

Hollow titania nanoshells (HTNSs), which were synthesized by a SiO2 sacrificial template method, were used to intensify the electrochemiluminescence (ECL) of luminol. The size, shell thickness and crystal phase, factors that are important in determining the efficiency, can be controlled by adjusting the template size, precursor concentration and calcination temperature, respectively. The structure of the HTNSs was characterized by transmission electron microscopy, scanning electron microscopy and X-ray diffraction spectroscopy. After structural optimization, the surface of indium tin oxide (ITO)-coated glass was modified with the HTNSs to act as a working electrode for a flow-injection analytical system. The heterostructure demonstrated an ECL emission intensity 150 times higher than that of the bare ITO. The research also revealed that the ECL of luminol on this modified electrode showed a very sensitive response to hydrogen peroxide with a detection limit of 4.6×10−10 M. In addition to discussing the intensifying mechanism of luminol ECL by HTNSs, we demonstrate that can be successfully applied to evaluate the gross antioxidant activity of garlic.