Critical trigger of self-assembled bimetallic Fe/Mn-MOF with SnS heterojunctions by persulfate activation for efficient tetracyclines photodegradation.

Developing advanced strategies, including exposing active site centers, regulating coordination environments, controlling crystallographic facets, optimizing electronic structures and constructing defects for enhancing photocatalytic performance is of great significance to improving the ecosystem. In this study, a novel self-assembled bimetallic Fe/Mn-MOF with SnS Z-scheme heterojunction photocatalyst was designed using a facile multistep solvothermal method. Benefiting from the interfacial heterojunction synergistic effect, the photocatalysts exhibited an outstanding catalytic performance. Nearly 91.4% efficiency of tetracyclines was degraded within 80 min through the assistance of a persulfate-based advanced oxidation process. DFT calculations utilizing the Fukui index identified the sites vulnerable to attack by the active species. As demonstrated by the trapping experiments and electron spin resonance (ESR), the involved oxygen-active species (•O and O) facilitated the rapid degradation of tetracycline. The degradation pathways were further guided in the elucidation of the rationale mechanism and the toxicity of derived intermediates was revealed. This work opens a new strategy for the rational design of bimetallic photocatalysts, emphasizing interface-modulated heterojunctions for efficient solar energy conversion.