Optical Investigations of Film Formation and Removal on Gold Anodes in Acidic Oxalate Solutions

Abstract

RECENT investigations of the oxidation of oxalate ions in acidic solutions using gold anodes have provided electrochemical evidence for the formation of a film on this anode during steady-state electrolysis at potentials well below that for Au2O3 formation, 1.36 V normal hydrogen electrode1. The determination of the nature of the film on gold at potentials below 1.36 V using electrochemical techniques has introduced uncertainties as to whether the film is a ‘three dimensional’ oxide film or a ‘two dimensional’ chemisorbed oxygen film. Some investigators2–5 using charging curves as their basis conclude that the formation of an oxide occurs only above 1.36 V, the formation of a chemisorbed oxygen film being the process occurring below this potential. The formation of this chemisorbed oxygen film begins at potentials as low as 1 15 V (ref. 6). Other work, however, also based on electrochemical evidence, indicates that the formation of an oxide film does occur below 1.36 V (ref. 7).