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[Display omitted] • Z-scheme silver phosphotungstate/polyimide photocatalyst was synthesized. • Self-assembly and in-situ solid-phase thermal polycondensation were utilized. • Keggin units act as the shuttle redox mediators for Z-scheme photocatalytic system. • The target photocatalysts exhibit enhanced visible light photocatalytic activity. • Oil-H 2 O mixed system can enhance the degradation process of AFB1. Silver phosphotungstate/polyimide (MAPI) photocatalyst was successfully synthesized by a multi-step strategy combining the self-assembly and in-situ solid-phase thermal polycondensation. The construction of MAPI photocatalysts and their photocatalytic activity were investigated. The polyimide (PI) in MAPI photocatalysts obtains the weakened π-π stacking structure and more dendritic crystalline structure. However, the POMs-π interactions, charge-transfer form in conjugated organic ligands-modified polyoxometalate (POMs) materials, and the close contact between main components are beneficial to the charge transfer in MAPI photocatalysts. The coordination interactions of Keggin anions and organic ligands allow the Keggin units released during the thermal treatment process to act as shuttle redox mediators for Z-scheme heterojunction photocatalysts. The changes related to the physicochemical and interfacial interactions of the components enable the MAPI photocatalysts to exhibit the enhanced photocatalytic activity. Pristine PI shows little activity for photocatalytic degradation of Aflatoxin B1 (AFB1) under visible light (λ ≥ 420 nm) irradiation, but the rate constant k of 5-MAPI was 7.34 and 4.46 times than that of pristine AgPW and P25, respectively. The presence of H 2 O and the transfer behavior of AFB1 in the oil-H 2 O mixed system significantly promoted the photocatalytic degradation efficiency of AFB1 in peanut oil. Z-scheme charge transfer path and the photocatalytic degradation pathway of AFB1 were also proposed. Combined with the density functional theory (DFT) calculation results, AFB1 will be firstly degraded by the ·OH-induced cycloaddition reaction at the C19 = C20 of furan ring. Subsequently, methoxy (C23-O22), furan ring, lactone ring and carbonyl group (C9 = O10) are degraded in sequence. This work can provide some interesting insights into the construction of polymer/insoluble POMs photocatalysts and the photocatalytic degradation of exogenous harmful substances in vegetable oil. [ABSTRACT FROM AUTHOR]

[Display omitted] • E–TiO 2 @rGO with OVs were prepared through crystal defect engineering. • Mixed crystal and OVs enhanced electron-hole pairs separation efficiency. • E–TiO 2 @rGO improved 2,4,6-TCP dichlorination process and degradation efficiency. • The toxicity of 2,4,6-TCP and its intermediates was evaluated via ECOSAR and DFT. Chlorophenolic pollutants pose serious threats to the aquatic ecosystem. Photocatalysis technology has broad prospects for decontamination. In this work, MXene-derived TiO 2 nanocomposites with mixed-crystal characteristics and oxygen vacancies (OVs) (E–TiO 2 @rGO) were successfully synthesized by atmosphere modulation. Compared with commercial TiO 2 and N 2 –TiO 2 @rGO (anatase phase), the rate constants of E–TiO 2 @rGO (0.06874 min−1) over 2,4,6-trichlorophenol (2,4,6-TCP) degradation increased 4 and 1.3 times, respectively. The enhanced photocatalytic performance was attributed to the co-existence of anatase and rutile phases. On the one hand, the mixed-crystal phase narrowed the band gap, broadening the light absorption range. On the other hand, it induced the generation of OVs, which has been demonstrated by DFT calculation. The presence of OVs improved the adsorption and activation of O 2 and H 2 O molecules, beneficial for the formation of active free radicals. In addition, the incorporation of rGO promoted the separation of electron-hole pairs. The Gibbs free energy of 2,4,6-TCP degradation revealed that the OVs and mixed-crystal could reduce the energy barrier of the rate-determining step, thereby boosting the dichlorination efficiency of 2,4,6-TCP. The superoxide free radical (O 2 −) was determined as the dominant active species. Finally, a possible mechanism of 2,4,6-TCP degradation with E–TiO 2 @rGO was clarified clearly. The proposed mixed-crystal defect engineering represents a novel strategy in the design and synthesis of photocatalysts. [ABSTRACT FROM AUTHOR]