Effects of Tb-Doped BiVO₄ on Degradation of Methylene Blue

Bismuth vanadate (BiVO₄) is a narrow-bandgap semiconductor (~2.41 Ev) that responds to visible light. The efficiency of degradation of organic dyes is indexed by methylene blue (MB). After 150 min, the efficiency of MB degradation by pure BiVO₄ was about 20%. Its adsorption performance and electron–hole pair migration ability are weak, and the photocatalytic activity of pure BiVO₄ needs to be improved. BiVO₄ doped with rare earth ions can facilitate the separation of photogenerated electron–hole pairs, thereby enhancing photocatalytic activity in the visible light range. This study investigates changes in the structure and morphology of BiVO₄ doped with different atomic percentages of terbium (Tb). BiVO₄ powders were prepared by the hydrothermal method with different atomic percentages of Tb (at% = 0, 1, 3, and 5). Doping Tb benefits the coexistence of monoclinic/tetragonal heterostructures, which changes the band gap and improves degradation efficiency. After 150 min of visible light irradiation, the photocatalyst doped with 3 atomic percent of Tb exhibited 98.2% degradation of methylene blue. The degradation percentage of MB remained stable in the presence of 3at%Tb-doped BiVO₄ composite. The optimal parameters for the amount of photocatalyst added were studied. Real-field simulations of metal ions and inorganic salts both retain high levels of degradation efficiency.