Enhanced Upconversion Luminescence in Controllable Self-Assembled BiOBr:Yb3+/Er3+ 3D Hierarchical Architectures and Their Application in NIR Photocatalysis

In this work, self-assembled Yb3+/Er3+-codoped BiOBr 3D flowerlike hierarchical architectures (HAs) were synthesized via hydrothermal method. With increasing pH values, the thickness of samples became thinner, and the morphology transforms from 2D nanosheets to self-assembled 3D HAs. Under the excitation of 980 nm, 3D flowerlike BiOBr:Yb3+/Er3+ HAs showed a significant enhancement in the upconversion (UC) emission, which was about 505 times that of the 2D nanosheets. The mechanisms for the enhancement of UC emission have been discussed. Moreover, all the samples showed effective photocatalytic activity for the RhB degradation and obviously enhanced performance with increasing pH values under NIR and simulated solar light irradiation due to the internal electric field effects and efficient utilization of UC emissions. This work gives insight into the guidance of fabricating efficient self-assembled 3D flowerlike BiOBr:Yb3+/Er3+ HAs UC materials, which have great potential for the applications in NIR-activated photocatalysts.