Synthesis Of Gold Nanoparticles By Using Transitional Metal-Substituted Heteropolyanions As Photocatalysts And The Electrochemical Behavior Of Their Modified Electrode

Based on similar composing and structure, 4 kind of transitional metal-substituted 12-tungstophosphates—PW₁₁M (M=Fe³⁺,Zn²⁺,Ni²⁺,Cu²⁺) are prepared by the same method. Then their photocatalysis are observed in detail in the synthesis of gold nanoparticles by liquid phrase photochemistry methods. Besides, the nanoparticles capped by PW₁₁M modified in GC electrode surface successfully in our experiments, and the electrochemical behavior of such modified electrodes was studied by CV curves. The experimental results as follows:1. The UV-vis spectra and TEM images indicate that PW₁₁M can be used as photocatalysts, but their photocatalysis are different respectively. In the same conditions, the formation speed of gold nanoparticles is more rapidly with PW₁₁Fe (Zn) than by using PW₁₁Ni(Cu), and in the formal system nanoparticles are nearly all uniform spherical, while there are lots of triangular/truncated triangular and other irregular structures appear in the latter. However, factors contributing to the formation of nanotriangles/nanoprisms are not well understood.2. The influence factors to nanoparticles property are investigated by adjust different experimental parameters such as the time of UV irradiation,the concentration of propan-2-ol or PW₁₁M. Increasing the time of UV irradiation, the uniform spherical nanoparticels can be easily obtained by using PW₁₁Fe (Zn) as photocatalysis, and the stability of gold colloids is promoted distinctly too. But as to PW₁₁Ni (Cu), the concentration of propan-2-ol plays a crucial role to size/morphology of gold nanoparticles, the formation speed of smaller uniform nanoparticles are raised dramatically as the concentration increasing, Thereby, the monodisperse and uniform spherical nanoparticles can also be synthesized by increasing the concentration of PW₁₁M or the time of UV irradiation when there is adequate propan-2-ol.3. The electrochemistry and their electrocatalysis of such functional nanoparticles (PW₁₁M-NG/PVP/GC) can be characterized by CV curves. Firstly, Its voltammetric response exhibits three pairs of waves attributed to two one-electron and a two-eletron redox process corresponding to the 12-tungstophosphates structures, which indicates that substituted transitional metal (M) doesn't participate in the redox reaction. But the CV curves are different respectively show that M affect Keggin structures or the property of tungstophosphates as well. All of such modified electrodes have efficient electocatalysis to H₂O₂ or NO₂^-, which can be demonstrated by relevant CV curves performed in the acid solution containing H₂O₂ or NO₂^-.