Significantly improvement of the photocatalytic performance of vermiculite/g-C3N4 composite by the modification of BiOBr

Vermiculite/g-C 3 N 4 /BiOBr composite (MCVB-X, X = 20, 50, 70, 90) with significantly improved photocatalytic performance was prepared by in-situ growing 20 wt%, 50 wt%, 70 wt%, 90 wt% of BiOBr nanosheets , respectively, on the surface of vermiculite/g-C 3 N 4 composite (MVC). With the increasing of BiOBr content, the photocatalytic performance of MCVB-X composites enhanced gradually. After 180 min of photocatalytic reaction under the visible light irradiation , the degradation rate of tetracycline (TC) by MCVB-50, which contained 50 wt% of BiOBr, reached 91.34 %, which was close to that of pure BiOBr and much higher than those of MVC and bulk g-C 3 N 4 (CN). The reaction rate constant (k) (0.0131 min −1 ) of MVCB-90 was 38.53 times and 6.24 times that of CN and MVC, respectively, which was also greater than that of pure BiOBr nanosheets (0.0098 min −1 ). The main reason for the significant improvement of photocatalytic performance of MCVB-X composites was that the construction of g-C 3 N 4 /BiOBr heterojunction promoted the separation and migration of photogenerated carriers and reduced the recombination rate of photogenerated electron-hole pairs. The agglomeration of BiOBr nanosheets was inhibited and contributed to the adsorption of pollutants. Moreover, the band structure , main active species (⋅O 2 − ) and photocatalytic degradation mechanism were proposed.