The surface oxides formed on electropolished gold by potentiostatic anodization in the range 1.2–1.85v vs . H + /H 2 have been studied by galvanostatic reduction at current densities between 10 and 1000 µa/cm 2 . Molar perchlorate solutions of p H 0.06 to 2.8 were employed. The extent of oxide formation is determined by the potential of anodization; the charge increasing linearly with the potential of formation in the range of 1.45–1.8v. Cathodic chronopotentiograms show that reduction of the oxide occurs at a definite potential which depends on the cathodic current density. Current‐ potential curves, constructed from the chronopotentiograms, follow a Tafel relation with a slope of 41 mv. The electrochemical order of the reduction reaction is −1.4 with respect to p H. Ease of reduction of the oxide, as measured by its rate of reduction at a fixed potential at any given p H, decreases with increase of potential of formation of the oxide. A mechanism for reduction is suggested in which it is assumed that the reduction of an intermediate (Au II ) is the slow step in the over‐all process.
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Brummer et al. (1964) studied this question.