Enhancement of photocatalytic activity of nano-scale TiO2 particles co-doped by rare earth elements and heteropolyacids

► Both rare earth ions and heteropolyacids are used to dope TiO2 photocatalysts. ► The synergistic effect of the co-doped photocatalyst was studied. ► Co-doped catalyst can prevent phase transition of anatase to rutile. ► Co-doped catalyst can decrease the band gap of TiO2.