Persistent Methyl Orange Degradation Ability of MgAl₂O₄:(Pr³⁺,Dy³⁺)/M-TiO₂ Luminescent Photocatalyst

Metal ions (Cr, Ni, Co) doped titania (M-TiO2) coupled with the long after glow phosphor MgAl2O4:(Pr3+, Dy3+) particles were synthesized by the sol-gel method, with the best mass ratio of MgAl2O4:(Pr3+, Dy3+) to M-TiO2 as 4:6. MgAl2O4:(Pr3+, Dy3+)/M-TiO2 had the persistent methyl orange (MO) photocatalytic degradation ability and the photocatalytic degradation went on reacting more than 90 min in dark after turning off the light. MgAl2O4:(Pr3+, Dy3+) emitted the light as a light source in dark which was absorbed by M-TiO2. The differences of MgAl2O4:(Pr3+, Dy3+)/Cr-TiO2, MgAl2O4:(Pr3+, Dy3+)/Ni-TiO2 and MgAl2O4:(Pr3+, Dy3+)/Co-TiO2 might be attributed to the difference in the metal ions doping. The composite MgAl2O4:(Pr3+, Dy3+)/Cr-TiO2 revealed the highest ability of persistent photocatalytic degradation methyl orange. Different metal ions doping made the TiO2 with different band gap.