Effect of (La, Ce, Eu) doping on structural, and optical properties of BiOI nanosheets: As a model of photocatalytic activity in heavy metal removal under visible light

A series of BiOI doped with lanthanide metals (lanthanide metals = La, Ce, Eu) were synthesized by solvothermal method and calcination method. The physical and chemical state of the as-prepared BiOI doped with lanthanide metals were characterize by characterization methods. The Hg0 photocatalytic oxidation was performed under visible light to further evaluate the photocatalytic activity. The experimental results indicate that the introduction of lanthanide ions into the BiOI lattice has an important effect on the photocatalytic activity. Moreover, it was found that BiOI doped with different lanthanide ions have different effects on the separation efficiency of charge carriers and the prevention of photo-corrosion. Compared with BiOI doped with La and Eu ions, the results identified that the incorporation of Ce was of a significant role in promoting the photocatalytic activity BiOI. It is proposed that the incorporation of La and Eu ions could induce excessive electrons on the BiOI surface under visible light, which leads to photo-corrosion of the catalyst in contact with the surface H2O. More importantly, the enhanced photocatalytic activity of Ce–BiOI is attributable to the oxygen storage capacity of the Ce3+/Ce4+redox pairs and surface defects that promote molecular oxygen activation to facilitate the photocatalytic oxidation reaction. This work can provide theoretical support for the future use of lanthanide metal substitution doped modified photocatalysts.