The electrocatalytic properties of the oxides of noble metals in the electrooxidation of methanol and formic acid

The electrooxidation of 0.25 M methanol as well as of 0.25 M formic acid wa s examined on oxides formed on the Au(111) electrode surface in 0.5 M H2SO4 and 0.5 M NaHCO3 at a sweep rate of 0.5 mV/s. In the case of methanol, the Au(111) surface in 0.5 M H2SO4 must be covered by oxides in order to catal yse its oxidation significantly. The current of formic acid oxidation also appears in the potential region before the oxide formation, but the catalyt ic activity is apparently deeper in the potential region of oxide formation . In 0.5 M NaHCO3 the inhibition of methanol oxidation and the apparent cat alytic activity of Au oxides in the case of formic acid oxidation are obser ved. The methanol electrooxidation on polycrystalline silver electrode was observed only in the potential region where the surface was covered by oxid es in 0.1 M NaOH and at a sweep rate of 0.1 mV/s. This reaction was used to measure the concentration of methanol in the methanol-formaldehyde mixture in the same electrolyte. (C) 2001 Elsevier Science Ltd. All rights reserve d.