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The utilization of the photo catalytic activation of permonosulfate (PMS) for the combined breakdown of pollutants has become a focal point in research. Layered double hydroxides (LDHs) have a unique layered structure which is conducive to the adsorption and diffusion of reactants, and can provide more active sites for photocatalytic reactions. The anions between the layers can be exchanged with a variety of substances so that specific catalytically active species can be introduced as needed. LDHs themselves have certain catalytic activity, which can produce synergistic catalysis between LDHs and the supported photocatalytic active substances, and further improve the degradation effect of antibiotics. In actual wastewater treatment, LDHs as a catalyst carrier have a good application prospect. However, the poor activation effect is attributed to the low separation efficiency of catalyst carriers and insufficient active sites. In this study, a dual active site system consisting of Co and Fe, known as CoFe-LDHs@MoS2, was developed as a catalyst to facilitate the synergistic degradation of norfloxacin (NOF) by PMS under visible light. The findings demonstrate that the material possesses an effective capacity for the synergistic degradation of NOF. A comprehensive investigation was conducted to assess the impact of different catalysts, PMS dosage, degradation systems (Vis, PMS, or Vis PMS), catalyst dosage, NOF concentration, pH, and cycle times on the degradation performance. The active free radicals, degradation pathways, and intermediate toxicity were elucidated through capture experiments, Electron Paramagnetic Resonance Spectrometer (ESR) analysis, a liquid mass spectrometry (LC-MS) toxicity assessment, and theoretical calculations. This research offers a novel approach for designing catalysts with exposed high activity sites for the effective removal of NOF from environmental water. [ABSTRACT FROM AUTHOR]

In the present study, we prepared novel polyaniline supported W 18 O 49 (PANI/W 18 O 49 ) nanocomposite by in situ oxidative polymerisation method. We herein focused on enhancing the stability and the photocatalytic performance of W 18 O 49 . The prepared PANI/W 18 O 49 was thoroughly characterized by FTIR, TEM, XRD, BET, UV–vis DRS and PL. The PANI support presented a great effect on the light harvesting and photo-charge transfer of the W 18 O 49 , and the optimum percentage of was found to be 10 wt%. As for treating Cr(VI), the effect of important water quality parameters (such as pH, ions, NOM, DO, temperature and SOAs) on photocatalytic performance was investigated under the visible light irradiation (λ > 420 nm). SOAs were shown to exert a dramatic accelerating influence on Cr(VI) reduction in the system. The obtained 10%-PANI/W 18 O 49 can completely catalytically reduce 1 mM Cr(VI) in the presence of tartaric acid (1:3) within 50 min. Meanwhile, it can be recycled at ten times without any loss of photocatalytic efficiency, indicating the high stability of the as-prepared photocatalyst. The results of the study demonstrate the potential of the new obtained photocatalyst in efficient utilization of solar energy for treating aqueous Cr(VI). [ABSTRACT FROM AUTHOR]

Sulfamethoxazole (SMX) is a common antibiotic used mainly for bacterial treatment. In this study, a novel three-dimensional cobalt-manganese bimetallic layered double hydroxide graphene hydrogel (CoMn-LDHs/rGO) has been prepared for photo-assisted permonosulfate (PMS)-activated degradation of SMX in water. Compared with the CoMn-LDHs/rGO + PMS and CoMn-LDHs/rGO + Vis systems, the degradation effect of CoMn-LDHs/rGO + PMS + Vis system is the best, and the degradation effect of CoMn-LDHs/rGO system could reach more than 98% under the optimal conditions. After 10 cycles, the catalytic degradation performance of CoMn-LDHs/rGO system remained good, while effectively preventing the leaching of metal ions. Based on the synergistic effect of photocatalysis and PMS oxidation, electron spin resonance spectroscopy and quenching experiments showed that three active substances (•OH, •SO 4 − and O 2 •−) were involved in the degradation of SMX. Density functional theory and liquid chromatography-mass spectrometry (LC-MS) results further proposed the SMX degradation transformation calculation. As expected, the study of the reaction mechanism of 3D CoMn-LDHs/rGO assisted PMS activation under visible light provides an efficient and rapid method for the sustainable degradation of pollutants in water system. [Display omitted] • Co 3 Mn-LDH/GH activates PMS under light-assisted conditions. • Reaction and optimal SMX degradation conditions can be controlled and selected. • Co 3 Mn-LDH/GH + PMS + Vis shows better chemical properties. • Sulfate and hydroxyl radicals are the major activation groups for SMX degradation. [ABSTRACT FROM AUTHOR]

In order to alleviate the increasingly serious energy problems, the researches and developments of photocatalysts with efficient solar energy utilization, low price and cost, and long-term stability are the critical problem to expand the application technology of photocatalysis. In this work, Co doped Sn 3 O 4 and g-C 3 N 4 were constructed into an S-scheme Co–Sn 3 O 4 /g-C 3 N 4 heterojunction photocatalytic system by simple and feasible solvothermal method for photocatalytic H 2 evolution. And different loading amounts of Co–Sn 3 O 4 /CN-X were obtained by mean of changing the dosage of Co–Sn 3 O 4. The synthesized photocatalysts represented exceptional H 2 evolution performance under visible light irradiation (λ>420 nm), among which Co–Sn 3 O 4 /g-C 3 N 4 -3 showed the best performance, and the H 2 yield reached 1793.88 μmol h−1 g−1. This value was significantly higher than that of single catalysts Sn 3 O 4 (294.82 μmol h−1 g−1) and g-C 3 N 4 (1111.28 μmol h−1 g−1). Moreover, the H 2 yield of reused Co–Sn 3 O 4 /g-C 3 N 4 -3 sample kept above 1737.67 μmol h−1 g−1 during cyclic test. XPS, UV–vis DRS and a series of photoelectrochemical analysis ascertained the establishment of internal electric field and bending of the energy band between the interface of Co–Sn 3 O 4 and g-C 3 N 4 , which provided the possibility for Co–Sn 3 O 4 and CN to construct Co–Sn 3 O 4 /g-C 3 N 4 S-scheme heterostructure. What's more, the mechanism of producing H 2 on the surface of Co–Sn 3 O 4 /g-C 3 N 4 by oxidizing H 2 O was proposed. This work demonstrated the application prospect of reasonably designing g-C 3 N 4 based photocatalysts with exceptional stability, sterling functionality and prominent efficiency for H 2 evolution, and provided availed guidance for the research and development of g-C 3 N 4 based photocatalysts. [ABSTRACT FROM AUTHOR]

Photocatalysis is an effective method to degrade ranitidine (RAN), which is a typical precursor of nitrosamine dimethylamine (NDMA), an extremely potent human carcinogen. Herein, MXene-Ti 3 C 2 /MoS 2 composites were prepared by a hydrothermal treatment aiming to use them for the photocatalytic degradation of RAN and the reduction of NDMA formation potential (NDMA-FP) under visible light irradiation for the first time. The analysis of the morphology, chemical composition and structure of these composites as well as the results of electrochemical experiments showed that a heterojunction was formed between MoS 2 and Ti 3 C 2 , which facilitated the separation of electron-hole pairs and charge transfer, and thereby the photocatalytic performance. The MXene-Ti 3 C 2 /MoS 2 composite (MT-4) exhibited the best photocatalytic performance in 60 min, with the highest RAN degradation and mineralization efficiencies of 88.4% and 73.58%, and the lowest NDMA-FP of 2.01%. Active species, including •O 2 - radicals, h+ and •OH radicals, all contributed to the degradation of RAN, among which •OH radicals were the main active species involved in the photocatalytic activity. The mechanism of the photocatalytic degradation of RAN over MXene-Ti 3 C 2 /MoS 2 photocatalyst under visible light irradiation was proposed. This work opens up a new perspective on the applications of MXene-based materials for photocatalytic degradation of challenging pollutants. [Display omitted] • MXene-Ti 3 C 2 /MoS 2 composites were prepared by a hydrothermal method. • A heterojunction was formed between MoS 2 and Ti 3 C 2 in the composite. • The highest RAN degradation and mineralization efficiencies were 88% and 74%. • The lowest NDMA formation potential of only 2.01% was achieved. • •OH radicals contributed most to the photocatalytic activity. [ABSTRACT FROM AUTHOR]

• Bi 4 O 5 Br 2 /g-C 3 N 4 heterostructure are prepared by a facile self-assembled method. • Bi 4 O 5 Br 2 /g-C 3 N 4 heterostructure exhibit an impressive production of H 2 O 2. • A Z-scheme photocatalytic mechanism is proposed for H 2 O 2 production. • The e−, ·O 2 − and h+ govern the photocatalytic production of H 2 O 2. Photocatalytic production of hydrogen peroxide from water and oxygen is a promising technique due to the green and sustainable solar-to-chemical energy conversion. However, in the absence of organic sacrificial agents as electron donors, the relatively low photocatalytic H 2 O 2 productivity is still far from satisfactory. Herein, we present a Z‐scheme photocatalytic production of hydrogen peroxide over Bi 4 O 5 Br 2 /g-C 3 N 4 heterostructure under visible light without additive organics. The obtained Bi 4 O 5 Br 2 /g-C 3 N 4 heterostructure exhibited a highest H 2 O 2 production of 124 μM in 60 min by a Z-scheme photocatalytic mechanism. The photoinduced electrons of Bi 4 O 5 Br 2 combine with the holes of g-C 3 N 4 at the contact interface, and the e− and h+ of the heterostructure are mainly derived from the conduction band of g-C 3 N 4 and valence band of Bi 4 O 5 Br 2 , respectively. As such, more e− and h+ of Bi 4 O 5 Br 2 /g-C 3 N 4 heterostructure are available to reduce oxygen and oxidize water, respectively, with more ·O 2 − and ·OH generated and thus more H 2 O 2 produced. [ABSTRACT FROM AUTHOR]

• MoS 2 /RGO heterojunctions were synthesized using a hydrothermal method. • Ranitidine was chosen for photodegradation in 60 min under visible light. • Highest efficiencies of degradation (74%) and mineralization (50%) were achieved. • NDMA formation potential after photodegradation maximally decreased to 6.76%. • Hydroxyl radical was the most important active group in photocatalytic degradation. Ranitidine (RAN) is a primary precursor of NDMA (N-nitrosodimethylamine), which is a carcinogenic disinfection by-product that poses a serious threat to human health and environmental safety. Photocatalysis is a useful and effective technology for degrading RAN and eliminating its NDMA formation potential. In our work, MoS 2 /RGO (reduced graphene oxide) composites with various mass ratios were fabricated using a hydrothermal method and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectrometer. In terms of the photocatalytic degradation of RAN, the MoS 2 -RGO-3 composite (with 23.2 wt% RGO) achieved the best performance with 74% RAN photodegraded in 60 min under visible light. Furthermore, this composite obtained the highest RAN mineralization efficiency (50%) and had the lowest NDMA formation potential (6.76%). Additionally, the generated hydroxyl radicals (OH), superoxide radicals (O 2 –) and holes (h+) were involved in the RAN photocatalytic degradation process, where OH was the most important active ingredient. This work may provide a new basis for the preparation of better photocatalysts under visible light for micro-pollutant degradation in water treatment. [ABSTRACT FROM AUTHOR]

In this study, different carbon quantum dots (CQDs)/NaBiO 3 hybrid materials were synthesized as photocatalysts to effectively utilize visible light for the photocatalytic degradation of contaminants effectively. These hybrid materials exhibit an enhanced photocatalytic reduction of hexavalent chromium (Cr(VI)) in the aqueous medium. Zero-dimensional nanoparticles of CQDs were embedded within the two-dimensional NaBiO 3 nanosheets by the hydrothermal process. Compared with that of the pure NaBiO 3 nanosheets, the photocatalytic performance of the hybrid catalysts was significantly high and 6 wt.% CQDs/NaBiO 3 catalyst exhibited better photocatalytic performance. We performed the first-principles density functional theory calculations to study the interfacial properties of pure NaBiO 3 nanosheets and hybrid photocatalysts, and confirmed the CQDs played an important role in the CQDs/NaBiO 3 composites. The experimental results indicated that the enhanced reduction of Cr(VI) was probably due to the high loading of CQDs (electron acceptor) on NaBiO 3, which made NaBiO 3 nanomaterials to respond in visible light and significantly improved their electron-hole separation efficiency. Image, graphical abstract [ABSTRACT FROM AUTHOR]

[Display omitted] • Metal-free RP/PDI was successfully prepared by a facile self-assembly method. • The RP/PDI exhibited impressive performance in removing bromate. • A p-n junction mechanism for reducing bromate on RP/PDI was proposed. • The possible removal pathways of bromate were discussed. Using solar energy to reduce bromate in drinking water is promising. Unfortunately, most effective photocatalysts for bromate conversion are metal-based semiconductors. Here, for the first time, metal-free hybrid composites made of red phosphorus and perylene diimide (RP/PDI) were successfully designed and constructed, and their excellent catalytic performance for removing bromate under visible light was demonstrated. Characterizations such as XRD, FTIR, Raman, SEM and XPS confirmed the successful preparation of the hybrid catalyst, and the impact of water matrices suggests that it can be used for the actual treatment of bromate. The bromate reduction rate of the prepared RP/PDI-2 was 4.2 times and 7.0 times faster than pure RP and PDI, respectively. As evidenced by EIS and EPR results, this improvement is mainly due to the formation of p-n heterojunctions, which enhanced the separation of charge carriers and inhibited the production of active species (O 2 − and OH) with strong oxidative capabilities. Considered holistically, the current study provides not only a metal-free photocatalyst with good photoreduction performance, but also some guidance for the rational design of hybrid photocatalyst in the treatment of aqueous bromate. [ABSTRACT FROM AUTHOR]