The Research And Application Of Sensitization For Electrochemiluminescence Of Luminol From Nano-metal Oxides

This paper researched the synthesis of MnO₂ nano-particles and discussed the influence of products from Surfactants. The best concentration of nano-MnO₂ that can enhance luminol's electrochemiluminescence(ECL) was found through adding nano-MnO₂ into the luminol solution (pH=12.5) and modifying it on the surface of platinum electrode by silica sol-gel film. On this basis, the research was carried out to develop an ECL electrode by modifying the nano-MnO₂ and luminol simultaneously on the surface of platinum electrode by sol-gel method.TiO₂ nano-particles were also synthesized. The best concentration of nano-TiO₂ that can enhance luminol's electrochemiluminescence (ECL) was found through adding nano-TiO₂ into the luminol solution (pH=12.5). The sensitization for ECL of luminol from nano-TiO₂ was more obvious through modifying it on the surface of platinum electrode and higher stability of signal and signal/noise ratio were got. On this basis, an ECL electrode was constructed by modifying the nano-TiO₂ and luminol simultaneously on the surface of electrode by sol-gel method. The experimental result showed that, the performance of this ECL electrode was better than any other ECL electrode under the same conditions. It was found that the ECL signal of this ECL electrode respond to the concentration of H2O2 with good linearity at a certain concentration range. This could be used to mensurate the concentration of H2O2 and the detection limit was low to 1×10-8mol/L. This ECL electrode was applied to test the antioxidant capacity of grapes. The result was that the antioxidant capacity of the grape seed was much better than grape meat.The mechanism of sensitization for ECL of luminol from nano-TiO₂ was discussed and it was explained that the effect was resulted from two reasons. One reason was that luminol was adsorbed on the surface of nano-particles of TiO₂, it made energy transfer become possible. Another reason was that reactive oxygen species catalytic generated from nano-TiO₂ transfer energy to luminol in the condition of applying voltage.On the basis of electrochemiluminescence electrode obtained, this paper has developed a flow-injection electrochemiluminescence detector.