Photocatalytic degradation of an azo dye using Bi3.25M0.75Ti3O12 nanowires (M = La, Sm, Nd, and Eu)

Bi3.25M0.75Ti3O12 (BMT, M = La, Sm, Nd, and Eu) nanowires were synthesized through simple hydrothermal route and their structural and photocatalytic properties were investigated. XRD results indicated that these compounds are of layered perovskites structure. In addition, the band gaps of Bi3.25La0.75Ti3O12 (BLT), Bi3.25Sm0.75Ti3O12 (BST), Bi3.25Nd0.75Ti3O12 (BNT), and Bi3.25Eu0.75Ti3O12 (BET) were estimated to be about 2.403, 2.594, 2.525, and 2.335 eV, respectively. Their photocatalytic activities were evaluated by photocatalytic degradation of methyl orange (MO) under visible light irradiation (λ > 420 nm). Bi3.25M0.75Ti3O12 (M = La, Sm, Nd, and Eu) showed markedly higher catalytic activity compared to traditional N doped TiO2 (N-TiO2) and pure bismuth titanate (Bi4Ti3O12, BIT) for MO photocatalytic degradation under visible light irradiation. The high photocatalytic performance of Bi3.25M0.75Ti3O12 photocatalysts could be attributed to the strong visible light absorption and the recombination restraint of the e−/h+ pairs resulting from doping of rare earth metal ions. Furthermore, BET nanowires exhibited the highest photocatalytic activity.