Green microwave switching from oxygen rich yellow anatase to oxygen vacancy rich black anatase TiO2 solar photocatalyst using Mn(ii) as ‘anatase phase purifier’

Abstract

Green and rapid microwave syntheses of ‘yellow oxygen rich’ (YAT-150) and ‘black oxygen vacancy rich’ (BAT-150) anatase TiO₂ nanoparticles are reported for the first time. YAT-150 was synthesized using only titanium(IV) butoxide and water as precursors. The in situ precursor modification by Mn(II) acetate switched anatase TiO₂ from YAT-150 to BAT-150. The entry of Mn²⁺ into the crystal lattice of anatase TiO₂ paved the way for peak texturing in the existing peak orientations along with the origin of three new anatase TiO₂ peaks in the (103), (213) and (105) directions. The as synthesized ultra-small (∼5 nm) yellow and black anatase TiO₂ nanoparticles were found to be two fold and four fold more photoactive than the commercially available photocatalyst Degussa-P25 under sunlight illumination.