AFM studies and electrochemical characterization of boron-doped diamond surfaces modified with metal oxides by the sol-gel method

作者：Suffredini HB; Salazar Banda GR; Tanimoto ST; Calegaro ML; Machado SAS; Avaca LA^*

来源：Journal of the Brazilian Chemical Society, 2006, 17(2): 257-264.

DOI：10.1590/S0103-50532006000200007

• modified diamond electrodes
• Sol-Gel technique
• metal oxides

Continuing previous investigations, direct surface modifications of boron-doped diamond ( BDD) electrodes with metal oxides ( PtOx, RuO2, IrO2 and PbO2) and with some mixed composites were carried out by the Sol-Gel technique. The materials were studied by atomic force microscopy ( AFM) to determine their surface topologies and by electrochemical techniques to establish the catalytic activity towards the oxygen evolution reaction ( OER) and also, for the PtOx and PtOx-RuO2 composites, the ethanol oxidation reactions in acid media. The stability of PtOx coating covered by a Nafion (R) film was also tested by long-term operation. The AFM results indicated sites of heterogeneous deposition and the electrochemical studies demonstrated that the active surface area changed considerably with the proposed method of modification. The IrO2/BDD electrode showed the best performance to the OER with the onset of the oxidation current at similar to 1.4 V, a value 200 mV lower than for the PtOx/BDD electrode. The enhanced stability of PtOx/BDD electrodes achieved by the application of a Nafion (R) film and already reported in acid media was further proved using the ethanol oxidation reaction. Only a small loss of activity ( 6%) was observed after 4-hours electrolysis while one-thousand voltammetric cycles left the surface practically unchanged. In addition, preliminary studies for the same reaction on PtOx/BDD and PtOx-RuO2/BDD electrodes demonstrated the excellent activity of these mixed Sol-Gel coatings on the BDD surface and the possibility of further investigations for practical applications.

• 出版日期2006-4