Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7834420 | Applied Surface Science | 2018 | 8 Pages |
Abstract
Highly defected SiO2 nanotubes (SiO2-NT) were obtained by a simple sol-gel procedure followed by calcination. Boron-doped diamond (BDD) polycrystalline films coated with SiO2-NT were used as working electrodes and, unexpectedly, cyclic voltammetric experiments have shown that the concentration of both positive and negative defects at the surface is high enough to enable redox processes involving positively charged Ru(bpy)32+/3+ to occur. Conversely, no electrochemical activity was put into evidence for Fe(CN)63â/4â species, most likely as a result of the strong electrostatic repulsion exerted by the negatively charged SiO2 surface. The concentration of surface defects was further increased by a subsequent thermal treatment in a hydrogen atmosphere which, as EIS measurements have shown, significantly promotes Ru(bpy)32+ anodic oxidation. Digital simulation of the voltammetric responses demonstrated that this treatment does not lead to a similar increase of the number of electron-donor sites. It was also found that methanol anodic oxidation at hydrogenated SiO2-NT-supported platinum results in Tafel slopes of 116-220â¯mV decadeâ1, comparable to those reported for both conventional PtRu and Pt-oxide catalysts.
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Authors
Nicolae Spataru, Crina Anastasescu, Mihai Marian Radu, Ioan Balint, Catalin Negrila, Tanta Spataru, Akira Fujishima,