The p-n heterojunction-engineered Bi₂MoO₆/KNbO₃ with 2D/3D architecture for enhanced photocatalytic activity towards benzene-containing contaminants under visible light illumination

It is extremely challenging for multi-targeted removal of benzene-containing contaminants (BCCs) due to their complex structure. Here, we successfully fabricate a novel two-dimensional (2D)/three-dimensional (3D) Bi2MoO6/KNbO3-3 (the molar ratio of Bi2MoO6 to KNbO3 is controlled at 1:3) p-n heterojunction through in-situ growth method, which can effectively degrade both typical BCCs: rhodamine B (RhB, 91.3% in 60 min) and oxytetracycline hydrochloride (OTC-HCl, 80.7% in 90 min). Bi2MoO6/KNbO3-3 exhibits great stability after four cycles with low metal ions leaching (< 0.34 ppm). The possible degradation pathways of typical BCC are proposed with the combination of N-de-ethylation, chromophore cleavage and mineralization, 14 intermediates are clarified. Three-dimensional excitation-emission matrix fluorescence spectra (3D EEMs) are conducted to grasp the overall change of OTC-HCl. Moreover, Bi2MoO6/KNbO3-3 can simultaneously degrade coexisted BCCs (RhB, malachite green and methylene blue) in real surface water under visible light illumination with the removal rates of 85.8%, 97.7% and 97.7%, respectively. This work provides a novel strategy for multi-targeted removal of BCCs in real surface water, and demonstrates that the structure of 2D/3D p-n heterojunction can effectively limit the leaching of metal ions which will avoid the potential secondary pollution.