Search

Reactive oxygen species (ROS), as one kind of the most highly oxidizing oxidants, are difficult to generate and utilize in the natural light conditions, since many materials require external strong stimuli for ROS release to be effective as pollutant degradation or biocide. In this work, we surprisingly found the ROS generation on MIL‐100(Fe)/TiO2 driven by mild natural light. Then ROS generation patterns and mechanism was revealed by chemiluminescence (CL) and density functional theory (DFT). Meanwhile, rhodamine B (RhB) can also be removed by MIL‐100(Fe)/TiO2 under natural light, which further evidence the ROS generation under the natural light. This work provides a new direction for spontaneously generating ROS releasing without external strong stimuli and has the broad potential applications in the field of pollutant degradation or antimicrobials under natural conditions. [ABSTRACT FROM AUTHOR]

The coexistence of pollutants presents a great challenge to the implementation of photocatalysts. In this work, a novel MIL-101(Fe)/TiO2 composite prepared by in situ growth of MIL-101(Fe) on TiO2 was developed for the synergetic oxidation of MC-LR and Cr(VI) reduction. The heterojunction material shows elevated photocatalytic behavior under ultraviolet compared with the unary pollutant system. Furthermore, quenching experiments and electron spin resonance confirm that the enhanced photodegradation behavior is related to the synergistic effect between the photocatalytic reduction and oxidation process, in which MC-LR consumes the holes and Cr(VI) captures electrons, followed by efficient charge separation through the conventional double-transfer mechanism between MIL-101(Fe) and TiO2. This investigation provides a deeper understanding of the construction of MOFs/semiconductor heterojunctions for the pollutants removal in multi-component contaminants system. [ABSTRACT FROM AUTHOR]

Photo-induced holes (h + ) oxidation is an efficient approach for perfluorooctanoic acid (PFOA; C 7 F 15 COOH) removal. To maintain a high amount of h + on the surface of photocatalysts participating in the PFOA photodegradation could be a critical issue. Herein, a highly efficient spherical BiOBr-modified nano-TiO 2 (P25) was synthesised and used for PFOA photodegradation through direct oxidation with h + . A high number of h + could be generated and remain on the surface of P25/BiOBr due to the appropriate position of the conduction band (CB) and valence band (VB) levels between P25 and BiOBr. Meanwhile, PFOA molecules were coordinated to the P25/BiOBr's surface via unidentate binding, being directly activated and oxidised by h + , resulting in a decomposition yield of 99.5% (100 mg/L) under simulated solar light irradiation within 100 min, at the initial pH condition (3.5). A stepwise photodegradation pathway was proposed due to the significant intermediates detected as the short-chain perfluorinated carboxylic acids (C2-C7). Reactive oxygen species (ROS) generation, scavenging and trapping analysis indicated that the direct oxidation on h + followed PFOA degradation. In a real aqueous environment of Tangxun lake (adjusted pH 3.5), stable common anions and natural organic matter (NOM) would restrain the PFOA photodegradation. However, adding 10 mg/L of NO 3 - or HA could reduce the inhibition effect of PFOA photodegradation. These findings gave an alternative strategy to drive an h + directly oxidation to treat PFOA contaminated water bodies., (Copyright © 2022 Elsevier Ltd. All rights reserved.)