The Research Of Electrochemiluminescence Behavior Of Luminol On ITO Electrode

A serial of different sized In2O3 nano-particles were synthesized by microemulsion, sol-gel and azeotropic distillation methods and characterized by transmission electron microscope. In alkaline solution of pH 12.5, the influence of In2O3 nano-particles on the ECL of luminol was studied. The results showed that the ECL intensity of luminol was enhanced obviously in the presence of In2O3 nano-particles. The sensitization efficiency was related to the content and the size of In2O3 nano-particles. The paper also discussed the mechanism of the sensitization by UV-Vis spectra and fluorescence spectra.The ECL behavior of active oxygen on ITO electrode in the alkaline solution was studied. The results showed that when ITO glass as working electrode, the ECL observed was produced by active oxygen in the alkaline solution. The possible mechanism was given: under the pulse voltage, ITO nano-particles on the surface of ITO glass were excitated to a level of energy and the redox reactions of OH-,O2 and H2O2 occurred producing active oxygen molecules. Meanwhile ITO nano-particles at a level of energy adsorbed the active oxygen molecules and translated the energy to them so that the active oxygen molecules could reach the state of excited and the light was relieved when they returned to the ground state.The ECL mechanism of luminol on ITO electrode in the alkaline solution was studied. The results indicated that the phenomenon that ECL of luminol on the ITO electrode could occurre under a lower voltage was mainly related to the interaction between luminol molecules and ITO nano-particles. Luminol molecules could be adsorbed onto the surface of ITO nano-particles and it was possible that the energy could be translated between them. Under the lower voltage, ITO nano-particles were exitated to a level of energy and when luminol molecules on the surface of ITO electrode were oxidated to middle state and the energy was translated from ITO nano-particles to middle state of luminol which produced light eventually.Nanosized SnO2 powder was synthesized by sol-gel method and characterized by transmission electron microscope. The result showed that the average particle sizes of nanosized SnO2 was about 10 nm. In the chemiluminescence system of luminol-O2, the CL intensity of luminol was enhanced obviously in the presence of nanosized SnO2. This sensitization efficiency was related to the content of nanosized SnO2 and the dissolved oxygen .Based on this, it was educed that the CL intensity of luminol was linear with the content of dissolved oxygen in the presence of nanosized SnO2. This linear relationship could be used to determine the dissolved oxygen, and the detection limit was 0.3mg/L. This sensitization system can be used to improve the sensitivity of determined method based on the chemiluminescence of luminol. The paper also discussed the mechanism of the sensitization by UV-Vis spectrum and fluorescence spectrum.