CATHODIC ELECTRODEPOSITION OF SE ON TI ELECTRODES

The electrodeposition of Se on Ti has been studied as a function of Se O2 concentration, presence of a surfactant (sodium n-dodecylsulphate), electrode illumination and temperature. This process is characterised by (i) a reduction peak followed by a ''passive'' and a ''transpassiv e'' domain in cyclic voltammetry, (ii) a slow current decay followed b y an abrupt drop in chronoamperometry, and (iii) a sudden transition f rom a less to a more negative arrest potential in chronopotentiometry. This behaviour is specific to Ti cathodes and is not observed for oth er electrode materials. In the less negative potential domain, Se film growth stops at a limiting thickness which increases for deposits of better electronic conductivity. Se deposits may be grown further in th e ''transpassive'' potential domain. The reaction mechanism in the dif ferent potential domains is presumably different.