Photoreduction of NO3- and NO2- under visible light irradiation with layered H4Nb6O17/CdS and H2Ti4O9/CdS nanocomposites

The photoreduction of NO3- and NO2- was performed at 60 degrees C under irr adiation of visible light (lambda >400 nm) in the presence of unsupported C dS, H2Ti4O9/CdS and H4Nb6O17/CdS in 10 vol.% aqueous methanol solution. The photoreduction rate of NO3- proceeded in the presence of H4Nb6O17/CdS and H2Ti4O9/CdS nanocomposites although unsupported CdS, H4Nb6O17 and H2Ti4O9 d id not show photocatalytic activity for nitrate reduction under visible lig ht irradiation. The photoreduction rate of NO3- and NO2- changed significan tly depending on solution pH, i.e., with increasing solution pH the reducti on rate of NO3- increased, on the other hand, that of NO2- decreased.