Chapter III Bacteria Mediated Synthesis of Nanocrystalline TiO2 and ZnO and their Photocatalytic Applications

TiO2 and ZnO nanoparticles are probably the first ones that have gained entrance to the market for their photocatalytic and UV-absorbent properties. As large volumes of these nanoparticles are required by the industry, the search for environmentally gentle processes for the synthesis of the same is also growing strong. Continuing our quest with the microorganism based synthesis of nanomaterials, we present in this chapter that, when challenged with appropriate precursor, the bacterium Actinobacter spp. can lead to the formation of ZnO and TiO2 nanoparticles. The biological way of synthesizing these materials probably leads to the insitu doping of elements like C, F and N into their crystal lattice that is evidenced by a red shift in the absorption edge. As the doping is expected to affect the photocatalytic activity of these materials under different light conditions, studies to prove this have also been undertaken here. This chapter delineates those in detail.