Oxygen evolution on gold: The effects of alkali-metal cations and iron impurities from alkaline electrolytes

Abstract

Effects of alkali cations and iron impurities in alkaline electrolytes on the activity of gold surface for the oxygen evolution reaction (OER) are studied. Cyclic voltammograms obtained for bare gold evidenced no activity for OER in the potential window bellow 2.0 VRHE, while for gold electrodes multi-cycled in the hydr(oxide) region, i.e., 1.25–1.50 VRHE, the OER activity is high and present an onset potential of 1.55 VRHE. Linear sweep voltammetry shows that the OER activity depends on the nature of alkali cation in the solution and also on the content of iron incorporated onto gold oxide electrodes. In situ surface-enhanced Raman spectroscopy (SERS) detected a band at 790 cm−1 suggesting the presence of OO− species on Au close to 1.90 VRHE and a broader band at a relatively lower potential (1.55 VRHE) that could be related to Fe-like species OO−, OOH and/or FeO that were adsorbed on gold electrode at a relatively low potential (∼1.55 VRHE), such species are likely to be the reactive centers participating in the electrocatalysis of the OER in alkaline media.