A multi-technique study of gold oxidation and semiconducting properties of the compact α-oxide layer

The initial stage of gold oxidation at the quartz crystal electrode in a near neutral solution was studied by using potentiostatic and potentiodynamic sweep methods. The underpotential deposition of OH radicals was the first stage of the nucleation and formation of the phase oxide Au2O3. The composition of the oxide was determined by the X-ray photoemission spectroscopy (XPS). Three-dimensional (3D) progressive nucleation occurred under diffusion control. The electronic structure of the compact α-oxide film and the charge distribution at the oxide layer/electrolyte interface were examined using photopotential and capacitance measurements. Anodically formed oxide film on gold was highly-doped defect semiconductor of n-type conductivity.