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 been 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 semiconductor films is attributed to increased charge separation in these systems. Photoelectrochemical and photocatalytic degradation experiments carried out in both nitrogen- and oxygen-saturated solutions with an externally applied electrochemical bias provide useful information in optimizing semiconductor concentrations in a composite film.