Z-Scheme Heterojunction g-C 3 N 5 /Bi 5 O 7 I High-Efficiency Mercury Removal Photocatalyst

Abstract

Photocatalysis technology is an effective means to address the issue of energy and environmental pollution. In this paper, defect engineering is introduced to couple g-C 3 N 5 , which further improves the photocatalytic oxidation of mercury by Bi 5 O 7 I. The experimental results show that defect engineering can not only regulate superoxide radicals as intermediates but also act as active sites to accelerate carrier transport, thereby increasing the photocatalytic mercury removal efficiency to 96.2%. The chemical reaction rate of g-C 3 N 5 /Bi 5 O 7 I heterojunction photocatalyst was 8.01 times that of pure g-C 3 N 5 and 4.58 times that of pure Bi 5 O 7 I. Through XPS and active radical capture test experiments, it was found that ·O 2 − , h + , and ·OH play a major role in mercury removal experiments. Finally, a collaborative strategy of vacancy structure and built-in electric field is proposed, which improves the charge transport efficiency of g-C 3 N 5 /Bi 5 O 7 I Z-scheme heterojunction interface. Our work provides theoretical support for the application of g-C 3 N 5 and its composites in the field of flue gas mercury removal.