关键词: 过氧化氢氧化, Au单晶电极, 旋转圆盘电极

Abstract:

The oxidation reactions of hydrogen peroxide (H₂O₂) at Au(111) and Au(100) electrodes in 0.1 mol·L^-1 HClO₄ were investigated by using rotating disk electrode system. It was found that H₂O₂ could be readily oxidized to O₂ at both Au(100) and Au(111) surfaces with the onset potential close to its equilibrium potential. In contrast, the onset overpotential for H₂O₂ reduction was above 0.4 V, while the onset overpotential for H₂O₂ oxidation at Au(100) was ca. 0.1 V more negative than that at Au(111), this is probably due to special double bridge sites which facilitate the adsorption of OOH* intermediates and its further splitting of the O-H bond. When the electrode potential exceeded 1.2 V, the Au surface was gradually covered by oxides, which significantly inhibit the oxidation reaction of H₂O₂. The inhibition effect became more obvious at Au(111) than that at Au(100), which corresponds well to the worse reversibility for the formation and reduction of Au oxides at Au(111). Finally, the comparisons in the H₂O₂ oxidation behaviors at Au(100) and Au(111) with that at Pt(111) indicated that the onset potential for H₂O₂ oxidation at Pt(111) should also be quite close to its equilibrium potential, and the observed high onset anodic current was due to the mixed potential effects of both the oxidation and reduction of H₂O₂ which occurred at the interface simultaneously.

Key words: Hydrogen peroxide Oxidation, Au single crystal electrode, rotating disk electrode