GROWTH OF COLUMNAR GOLD ELECTRODES BY ELECTROREDUCING HYDROUS GOLD OXIDE LAYERS - KINETICS AND MECHANISTIC INTERPRETATION

Rough columnar structured gold electrodeposits were prepared in aqueou s 0.5 M H2SO4 by electroreducing a hydrous gold oxide layer built up o n a gold substrate by means of a fast periodic potential routine. The analysis of potentiodynamic and potentiostatic hydrous oxide layer ele ctroreduction data indicated the initial nucleation of gold clusters a t the metal/oxide interface. The growth of gold nuclei proceeded under a constant capture area condition for depositing gold ions contained in the hydrous oxide layer. Columnar gold electrodeposition was assist ed by the gel-like characteristics of the hydrous gold oxide layer. Go ld columnar growth ended as soon as the column tips reached the oxide/ solution interface. The proposed kinetic model accounts for the high s urface area development and surface fractal properties of this type of metal electrode.