Soft-chemical method for fabrication of SnO–TiO2 nanocomposites with enhanced photocatalytic activity

The present work reports a soft-chemical pathway for preparing SnO–TiO2 composite nanocrystallites as photocatalyst through co-hydrolysis of tetrabutyl titanate and tin (II) chloride followed by acidic peptization of the hydrolysate under mild conditions. The procedure is simple and straightforward, from which a well-dispersed semitransparent hydrosol sample is obtained. The freestanding nanocrystallites observed in the as-prepared composite show diameters of 3–5 nm. TiO2 nanoparticles have almost entirely transformed into anatase phase, and the trace amounts of Sn in existence are mainly found in SnO crystals with tetragonal structure. The photocatalytic activity of the SnO–TiO2 composites is confirmed through the photodegradation of methyl blue dye under visible light irradiation (λ > 420 nm). As a p-type semiconductor, the incorporated SnO effectively improves the photocatalytic activity of TiO2 through promoting the separation of photo-generated charge carriers, inhibiting their recombination, and facilitating the reduction of O2 by the photo-generated electrons.