Facile in-situ construction of highly dispersed nano zero-valent iron modified black TiO₂ Z-scheme recyclable heterojunction with highly efficient visible-light-driven photocatalytic activity

This research provides a innovatively designed mechanism of activating the passivation layer on Fe⁰ surface as semiconductor to construct a Z-scheme heterojunction in-situ for high-efficiency environmental remediation. Aggregation and passivation of Fe⁰ and poor visible-light absorption of TiO₂ were simultaneously improved by the facile synthesis of a recyclable Fe⁰@black-TiO₂ Z-scheme heterojunction without high-temperature hydrogen atmosphere. The results showed that tetracycline (TC) degradation efficiency with Fe⁰@black-TiO₂ was 1.23 and 2.63 times higher than that of pristine Fe⁰ and black-TiO₂, respectively. The superior degradation arose from strong reduction ability of highly dispersed Fe⁰ and in-situ constructed Z-scheme heterojunctions. High dispersion of Fe⁰, construction of the heterojunction, enhanced photodegradability of Fe⁰@black-TiO₂ were systematically elucidated by multiple characterization techniques. Furthermore, photodegradation pathways of TC based on the role of •O₂^- and •OH were identified. Our results have provided the necessary inspiration and guidance for the development and application prospect of Fe⁰@black-TiO₂ in environmental remediation.