Fabrication of oxygen-vacancy-adjustable Yb3+/Er3+ co-doped BiOBr 3D flowerlike hierarchical architectures with enhanced photocatalytic activity under broad spectrum (UV/vis/NIR) excitation

A novel Yb 3+ /Er 3+ co-doped BiOBr photocatalyst with 3D flowerlike hierarchical architectures were successfully fabricated through self-assembled process without any templates under hydrothermal conditions, and the structure and properties of the photocatalysts were characterized. The results indicate that Yb 3+ ions and Er 3+ ions are successfully doped into the lattice of BiOBr, and the as-obtained photocatalyst can respond the NIR light and emit red and green light due to the up-conversion effect of the rare-earth ions. Meanwhile, with co-doped Yb 3+ /Er 3+ ions content increasing, oxygen vacancy concentration in the photocatalyst rises. The oxygen vacancy will form the intermediate energy band, which can decrease the photon energy required for electronical transition, and thus help to utilize the luminous energy generated by up-conversion luminescence. Moreover, the appropriate introduction of defects (oxygen vacancy defect and impurity atom) can further promote the transfer and separation efficiency of photo-generated carriers. Hence, Yb 3+ /Er 3+ co-doped BiOBr photocatalyst exhibits enhanced photocatalytic properties under broad spectrum (UV/vis/NIR) excitation, which is about 4 times as high as that of pure BiOBr.