Enhancement of green upconversion luminescence of Yb3+/Tb3+ co-doped BiOBr nanosheets and its potential applications in photocatalysis

In this work, a series of Yb 3+ /Tb 3+ co-doped BiOBr nanosheets were synthesized by a simple solvothermal method, and the effect of Tb 3+ and Yb 3+ doping on the up-conversion (UC) luminescence was investigated. Under the excitation of 980 ​nm, BiOBr: Yb 3+ /Tb 3+ nanosheets displayed emission bands at 494, 544, 584 and 622 ​nm arise from transitions 5 D 4 → 7 F J ( J  ​= ​6, 5, 4, 3) of Tb 3+ ions, respectively. Furthermore, the concentration dependence of UC luminescence was comprehensively explored, and the BiOBr:15%Yb 3+ /3%Tb 3+ nanosheets exhibited the most outstanding luminescent properties by the cooperative energy transfer. Moreover, the degradation rate of RhB by Yb 3+ /Tb 3+ co-doped BiOBr reaches 98.9% for 30 ​min under full spectral irradiation, and 51.7% for 5 ​h under 980 ​nm irradiation, respectively. This work proves that Yb 3+ /Tb 3+ co-doped BiOBr nanosheets have excellent green UC emission and have potential application in the field of near infrared activated photocatalysts .