Studies On Sensitization For Electrochemiluminescence Of Luminol From Platinum-Gold Bimetallic Nanoparticles Modified Electrode

This paper reported the researches on sensitization of nano-bimetalic material for the electrochemiluminescence(ECL) of Luminol. The platinum-gold bimetallic nanoparticles with different component ratio and size were prepared by chemical reduction. The methods such as UV-Vis spectra, TEM and XRD were applied to characterize the properties of the nanoparticles. The information from these methods revealed that the prepared bimetallic nanoparticles were truly of alloy structure and absolutely not the mixture of two kinds of metallic nanoparticles. The component of the nanoparticles could be regulated for a series of Pt/Au ratio and the diameter of nanoparticles, which were determined by Laser-granulometer, could be regulated from 4.025-92.33nm by the method or condition. In alkaline medium of pH12.0, the bimetallic Pt-Au nanoparticle modified electrode, which was modified on a Pt disk electrode by electrodeposition, sensitized the electrochemiluminescence of Luminol. The sensitization efficiency reached as high as the 6:1 of Pt/Au ratio. The specific surface area of nanoparticles would be larger while the diminishing of size, it results in the higher surface activity, so smallest size of nanoparticles acquired highest efficient for almost one order of magnitude.We studied the atom distribution in the cell of Pt-Au bimetallic nanoparticles. They found that the crystalline structure is face centered cubic. A cell contains 10 Pt atoms and 4 Au atoms, The 4 Au atoms hold the 4 corners that are in the two diagonals, and they substitute Pt atoms in two steps. The paper also studied the interaction between bimetallic Pt-Au nanoparticle and Luminol. A compound formed between them, and energy transfers from one to the other. The DTA supported presume about the crystalline structure; the fluorescence analysis gave the evidence of interaction between bimetallic Pt-Au nanoparticle and Luminol. There are two reasons for Sensitization for Electrochemiluminescenceof Luminol from Platinum-Gold Bimetallic Nanoparticles Modified Electrode. One is as a nanoparticle; the Pt-Au bimetallio nanoparticle has catalysis such as size effect, surface effect and etc. It prolongs the interaction time of OH. and Luminol-.,thereby enhances the intensity of Luminol. The other reason is when Pt and Au were alloyed; the d band cavity in Pt was increased. The cavity became the adsorption of radicals in the solution. So the electrode surface adsorped more OH. and Luminol-. , Thereby enhances the intensity of Luminol.