Intensification Of Electrochemiluminescence Of Luminol On TiO₂Supported Au Atomic Cluster Nano-hybrid Modified Electrode

With TiO₂nanoparticles as carrier, a supported nano-material of Au atomiccluster/TiO₂nano-hybrid was synthesized. It was then modified onto the surface ofindium tin oxide （ITO） by Nafion to act as a working electrode for exciting theelectrochemiluminescence （ECL） of luminol. The properties of the nano-hybrid and themodified electrode were characterized by Scanning electronmicroscopy （SEM）,transmission electronmicroscope （TEM），X-ray photoelectron spectroscopy （XPS），UV-Vis absorption spectra，AA-Duo atomic absorption spectrometer （AAS） and Cyclicvoltammetric method （CV）. The experimental results demonstrated that the modificationof this nano-hybrid onto the ITO electrode not only efficiently intensified the ECL ofluminol, but also extends its practicable pH window and reduces the required excitingpotential to avoid some possible interference. The stability and repeatability of themodified electrode was also investigated, the intensity decreased by only3.5%over23days, suggesting a good stability. Also, the RSD values for seven consecutive pulses ofECL emission, seven repetitive detections, and the average ECL intensity on sevenelectrodes for2×10^-7M luminol in phosphate buffer of pH9.0, were evaluated as2.4%,3.4%and4.4%respectively. These results evidenced the good repeatability of themodified electrode.The modified electrodes are very sensitive to dissolved oxygen and hydrogenperoxide. The detection limits of dissolved oxygen and hydrogen peroxide were2μg/Land5.510-12M, respectively. The mechanism in that the light emission on this modifiedelectrode was also related to O₂and studied, and a reasonable mechanism was proposed.Based on the ECL response towards the ROS, the presented electrode could be appliedto evaluate the antioxidant efficiency of the extracts of Ganoderma lucidum sporepowders. The gross ROS scavenging efficiency was19.0mg O₂g-1with ethanol as the extraction solvent or13.7mg O₂g-1with water as the extraction solvent. Besides, themodified electrode was applied to detect Glutathione （GSH）, and satisfactory result wasreceived. The detect limit was2×10^-14mol/L.