Synthesis and enhanced visible light photocatalytic activity of g- C3N4/BiOClxBr1-x heterojunctions with adjustable energy band structure

Abstract

The g-C3N4/BiOClxBr1-x heterojunctions photocatalysts with different band gaps were successfully synthesized via a simple precipitation process. The photocatalytic activitys of the g-C3N4/BiOClxBr1-x composites were evaluated through the degradation of Tetracycline Hydrochloride (TC) under visible light irradiation. Compared with pure g-C3N4 and BiOClxBr1-x, the hybrids exhibited prominently enhanced visible light photocatalytic activity for the degradation of TC. The various photocatalytic perfprmances of g-C3N4/BiClxBr1-x heterojunctions with same content of g-C3N4 were determined by different optical absorption capabilities resulting from the band structures, which could be controlling by changing the molar ratio of Br to Cl in BiOClxBr1-x. The 10-CN/BiOCl0·5Br0.5 (g-C3N4 content: 10%) showed the highest photocatalytic activity toward TC, due to the optimal synergistic effect of bandgap structure and effective separation of electron-hole pairs. Furthermore, the capture experiments of 10-CN/BiOCl0·5Br0.5 during photocatalytic reaction were also carried out, the results indicted the holes (h+) and superoxide radicals (-O2-) were the main active substances causing the enhancement of photocatalytic activity. Finally, we proposed a reasonable photocatalytic degradation of this g-C3N4/BiOClxBr1-x heterojunction photocatalysts.