THE PREPARATION AND CHARACTERIZATION OF GOLD COATINGS ON TITANIUM - THE REDUCTION OF OXYGEN

Gold coatings on titanium substrates have been prepared (i) by spraying solutions of TI(IV) and Au(III) followed by thermal decomposition or (ii) by the electrodeposition or vacuum deposition of gold onto pre-formed oxide layers. These coatings have been characterized using scanning electron microscopy, energy-dispersive X-ray analysis and voltammetry and it is shown that the I-E responses for oxygen reduction are markedly different. For the preparation of hydrogen peroxide, a cathode made by electrodeposition of a layer of gold (about 4 mu m) onto thermally oxidized titanium showed the same performance as bulk gold. This coating was also stable and formed a very strong bond with the substrate. The coatings of mixed Ti-Au oxides show complex behaviour.