关键词: Keggin型钴取代杂多阴离子, 过氧化氢, 甲醇, 电催化氧化

Abstract: The electrochemical properties of the Keggin-type Co(II)-substituted heteropolyanion PW₁₁O₃₉Co(II)(H₂O)^5- (PW₁₁Co), as well as the electrocatalytic properties of PW₁₁Co towards the anodic oxidations of H₂O₂ and CH₃OH were studied using the electrochemical methods such as cyclic voltammetry and AC impedance spectroscopy in this paper. An electrocatalytic mechanism of PW₁₁Co as an anodic medium was also proposed. It was found that PW₁₁Co showed a pair of pseudo-reversible redox peaks at the potentials of 1.367 V/1.266 V, corresponding to the redox responses of the Co(II)/Co(III) couple, apart from two pairs of reversible W—O skeleton redox peaks. A proton was involved in the electrode process of the Co(II)/Co(III) couple with an exchange current density (i₀) of 5.7×10^-6 A·cm^-2. In particular, the couple exhibited a high electrocatalytic activity towards the anodic oxidation of H₂O₂ in an acidic solution of pH 2.5, which can be coupled to catalyze the methanol oxidation.

Key words: Keggin-type Co-substituted heteropolyanion, hydrogen peroxide, methanol, electrocatalytic oxidation