NANOSTRUCTURED SEMICONDUCTOR-FILMS FOR PHOTOCATALYSIS - PHOTOELECTROCHEMICAL BEHAVIOR OF SNO2 TIO2 COMPOSITE SYSTEMS AND ITS ROLE IN PHOTOCATALYTIC DEGRADATION OF A TEXTILE AZO-DYE/

Nanostructured semiconductor films of SnO2, TiO2 and SnO2/TiO2 have be en employed for electrochemical assisted photocatalytic degradation of a textile azo dye naphthol blue black (NBB). The degradation rate is significantly higher for SnO2/TiO2 composite films than SnO2 and TiO2 films alone. An effort has been made to correlate photoelectrochemical behavior of these films to the rate of photocatalytic degradation of NBB. The enhanced degradation rate of NBB using composite semiconducto r films is attributed to increased charge separation in these systems. Photoelectrochemical and photocatalytic degradation experiments carri ed out in both nitrogen- and oxygen-saturated solutions with an extern ally applied electrochemical bias provide useful information in optimi zing semiconductor concentrations in a composite film.