Novel recyclable Z-scheme g-C3N4/carbon nanotubes/Bi25FeO40 heterostructure with enhanced visible-light photocatalytic performance towards tetracycline degradation

Constructing Z-scheme heterojunction has been treated as a superior strategy to boost the photocatalytic activity of photocatalysts for the removal of organic contaminants. Herein, a novel recyclable Z-scheme g-C3N4/carbon nanotubes/Bi25FeO40 (CN/CNT/BFO) heterojunction photocatalyst was successfully fabricated adopting a facile hydrothermal technique with ultrasonic assistance, in which CNT acted as an electron transfer bridge between CN and BFO. As a result, the degradation efficiency of tetracycline (TC) over optimal CN/CNT/BFO heterojunction reached 87.9% after 120 min of visible light exposure, which was higher than that of pristine CN, BFO and CN/BFO. The mechanism analysis indicated that the facilitated photocatalytic performance was associated with the CNT mediated Z-scheme heterojunction, leading to an outstanding separation of photoexcited electron-hole pairs as well as a high redox ability in the process of photocatalysis. Moreover, the CN/CNT/BFO heterojunction exhibited wide pH adaptability, excellent magnetic recyclability and stability. Finally, the possible degradation pathways of TC over CN/CNT/BFO heterojunction were proposed through the determined degradation intermediates. This research could provide an insight into the construction of promising and novel CNT mediated Z-scheme heterojunction photocatalysts for environmental applications.