Enhanced debromination and degradation of 2,4-dibromophenol by an Z-scheme Bi2MoO6/CNTs/g-C3N4 visible light photocatalyst

Abstract

An artificial all-solid-state Z-scheme Bi2MoO6/CNTs/g-C3N4 composite has been synthesized by hydrothermal technique, and its photocatalytic properties was investigated by the debromination and degradation of 2,4-dibromophenol (2,4-DBP). The morphology and surface analysis indicated that the Bi2MoO6/CNTs/g-C3N4 composite was a veritable ternary heterojunction rather than a simply physical mixture. The CNTs acted as excellent electron mediator for charge transfer due to the matched Fermi level between the Bi2MoO6 and g-C3N4. The unique Z-scheme structure had a remarkable contribution to affect the recombination of the electrons and holes. The optimal Bi2MoO6/CNTs/g-C3N4 composite exhibited an outstanding photocatalytic activity than the pure Bi2MoO6 and g-C3N4 for the debromination and degradation of 2,4-DBP. The photoexcited electrons aggregated in the g-C3N4 conduction band, and the holes in the Bi2MoO6 valence band have played equally important roles in the 2,4-DBP degradation. Debromination was the primary step for 2,4-DBP degradation, and the debromination process was launched by the photoexcited electrons aggregated in the g-C3N4 conduction band. The major intermediates during the debromination process were monobrominated and bromine-free products. Finally, the intermediates were mineralized by the photoexcited holes and the subsequent hydroxyl radicals.