Electrochemical oxidation potential of photocatalyst reducing agents

In this investigation, salicylic acid, benzoic acid, citric acid, aniline and nitrobenzene were studied using the linear sweep voltammetry (LSV) technique. An aqueous system was used with KHCO3 as electrolyte. Linear sweep voltammograms are presented in which the electrochemical oxidation behavior of the organic compounds can be observed. The behavior of salicylic acid was widely studied because of its reproducibility. The oxidation potential for salicylic acid was between 1.0 and 1.1 V vs. Ag/AgCl. Plateaus instead of peak currents were observed at some experimental conditions. Correlations of peak current vs. the square root of the scan rate were determined. A linear behavior was observed. However, the shapes of the voltammograms were not consistent with the diffusional behavior predicted by theory. Other reactions such as gold oxidation and electrolyte decomposition affected the SA oxidation reaction. Adsorption tests on salicylic acid were also performed to account for the fact that it may be chemisorbsd on the gold surface. Regarding the other organic compounds, benzoic acid was not electrochemically active in the potential range studied. The oxidation potential observed for citric acid was nearly 1.1 V vs. Ag/AgCl. Aniline and nitrobenzene showed oxidation potentials of 0.45 and 1.6 V vs. Ag/AgCl, respectively. (C) 1999 Elsevier Science Ltd. All rights reserved.