Enhancement of photocatalytic activity in Tb/Eu co-doped Bi2MoO6: the synergistic effect of Tb–Eu redox cycles

Abstract

Tb/Eu co-doped Bi₂MoO₆ photocatalysts were successfully synthesized by a hydrothermal method, and their photocatalytic activity for the degradation of Rhodamine B (RhB) under visible light irradiation was researched. An obvious red-shift of the optical absorption edge for the co-doped samples was observed as compared to the single or non-doped Bi₂MoO₆. Raman spectra displayed the influence of Tb and Eu ions in the material structure, and the mixed valence states of Tb and Eu ions in the lattice of Bi₂MoO₆ were verified by XPS. The results of photoluminescence spectroscopy and photocurrent measurement demonstrated that the recombination of photogenerated electron–hole pairs was tremendously depressed by the synergistic effect of Tb–Eu redox cycles in the Tb/Eu co-doped Bi₂MoO₆ photocatalyst and the photocatalytic activity was improved. Furthermore, the proposed mechanism of the enhanced photocatalytic activity was discussed.