Plasmon Resonance Enhanced Photocatalysis Under Visible Light with Au/Cu–TiO₂ Nanoparticles: Removal Cr (VI) from Water as a Case of Study

Gold modified copper doped titania (Au/Cu:TiO₂) nanoparticles were synthesized by a modified sol gel method and characterized using XRD, optical and TEM based techniques. The as-prepared material contained anatase phase particles with quasi-spherical morphology, showing enhanced absorption in the visible region and low photoluminescence emission intensity. Photocatalytic reduction of Cr (VI) in aqueous suspension with the Au/Cu:TiO₂ catalyst under 532 nm laser radiation and a visible broad band lamp source yielded 96% and 45% removal, respectively, without any additives. The enhanced photocatalytic activity can be attributed to the improved plasmonic effect due to gold modification and the expanded visible absorption due to copper doping. Moreover a comparative study of the material properties and catalytic activity of TiO₂, Cu–TiO₂ and Au/Cu–TiO₂ was carried out.