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 Fe 0 surface as semiconductor to construct a Z-scheme heterojunction in-situ for high-efficiency environmental remediation. Aggregation and passivation of Fe 0 and poor visible-light absorption of TiO 2 were simultaneously improved by the facile synthesis of a recyclable Fe 0 @black-TiO 2 Z-scheme heterojunction without high-temperature hydrogen atmosphere. The results showed that tetracycline (TC) degradation efficiency with Fe 0 @black-TiO 2 was 1.23 and 2.63 times higher than that of pristine Fe 0 and black-TiO 2 , respectively. The superior degradation arose from strong reduction ability of highly dispersed Fe 0 and in-situ constructed Z-scheme heterojunctions. High dispersion of Fe 0 , construction of the heterojunction, enhanced photodegradability of Fe 0 @black-TiO 2 were systematically elucidated by multiple characterization techniques. Furthermore, photodegradation pathways of TC based on the role of •O 2 - and •OH were identified. Our results have provided the necessary inspiration and guidance for the development and application prospect of Fe 0 @black-TiO 2 in environmental remediation. A facile recyclable Fe 0 @b-TiO 2 with highly dispersed Fe 0 exhibits excellent reduction ability and constructs a Z-scheme heterojunction in-situ in the dark reaction, which is beneficial to the separation of photo-generated electron-hole pairs, the migration of carriers and the generation of highly active ROS (•O 2 - , •OH) during the photodegradation process, further realizing enhanced visible-light-driven photocatalytic ability for TC. • Facile synthesis of Fe 0 @black-TiO 2 with strengthened visible-light photocatalysis. • Enhanced TC removal via strong synergistic adsorption, reduction and photocatalysis. • Highly dispersed Fe 0 induced by black TiO 2 guarantees strong reduction ability. • In-situ constructed Z-scheme heterojunctions ensure superior photodegradation. • Novel heterojunctions of Fe 0 and black TiO 2 lead to dramatically improved activity.