Z-Scheme Heterojunction α-Fe₂O₃/Tubular g-C₃N₄ with C Defects for Photocatalytic Degradation of Microcystin-LR in Water: Generation and Effect of Critical Species ¹O₂

Abstract

Microcystin-LR (MC-LR) is susceptible to degradation by singlet oxygen ( 1 O 2 ) attack due to multiple unsaturated olefinic bond sites. In this study, the Z-scheme heterojunction α-Fe 2 O 3 /tubular g-C 3 N 4 with C defects (α-Fe 2 O 3 /TDCN) was synthesized via hydrothermal and cocalcination methods. The efficient generation of 1 O 2 was realized by enhancing the photogenerated carrier separation and oxygen adsorption capabilities and was used to investigate the degradation process and mechanism of MC-LR. The results show that the degradation rate of MC-LR can reach nearly 100% within 60 min under visible light irradiation, and α-Fe 2 O 3 /TDCN possesses good stability and environmental friendliness. The relationship between photocatalyst performance and 1 O 2 generation was analyzed by density functional theory (DFT) calculations. Based on probe experiments, LC–MS data, and DFT calculations, the mineralization process of MC-LR dominated by 1 O 2 was analyzed. This study provides a reference for addressing MC-LR pollution in eutrophic aquatic environments and the direction of specific control of MC-LR mineralization.