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Delicate fabrication grounded on 2D epitaxial heterostructure can be identified as an available strategy to sufficiently discover and utilize its preponderances. Herein, bismuth sulfide-bridged Bi2S3/sulfuretted ZnAl-LDHs (Bi2S3/ZnAlSx) heterojunctions were rationally designed and fabricated via simple ion-exchange and hydrothermal treatment methods. The photocatalytic activities of the heterojunction composites were evaluated for the degradation of tetracycline (TC) under visible-light irradiation. Compared to the ZnAl-LDHs and ZnAlSx, the composites showed the best visible-light-driven photocatalytic performance for TC degradation due to the intimate contact between ZnAlSx and Bi2S3. In additional, upon the proper weight ratio of Bi2S3 (20 wt%), the as-synthesized production exhibited the highest photodegradation efficiency for TC (90.89%) under visible-light irradiation. Surprisingly, the apparent reaction rate constant (k) of Bi2S3/ZnAlSx is approximately 3.3-folds higher than ZnAlSx. Moreover, the possible reaction mechanism of the enhanced photocatalytic activity was proposed resulting from inhibited the recombination between photogenerated electrons and holes. Additionally, the 20 wt% Bi2S3/ZnAlSx showed the high removal efficiency (80.18%) for TC pollutants after four continuous cycles. This work underlines the important of heterostructure construction and further testifies that bismuth sulfide-bridged Bi2S3/sulfuretted ZnAl-LDHs (Bi2S3/ZnAlSx) are promising photocatalysts for the decomposition of antibiotics from waste water under visible-light irradiation.

The ZnAl calcined layered double hydroxides/ZIF-8 composites (ZnAl-CLDH/ZIF-8) were successfully synthesized by a simple and efficient co-precipitation method. Characterizations including XRD, SEM, XPS, UV–vis DRS and EIS were used to investigate the structures and the morphologies of the fabricated photocatalysts. Furthermore, the photocatalytic properties of the composites were evaluated by the photodegradation of Methyl blue (MB) under irradiation. The catalyst showed a high efficiency (97.35%) at the mass ratio of ZIF-8 was 5%. It is worth mentioning that the removal efficiency of MB is still higher than 90% for reused ZnAl-CLDH/ZIF-8 after five cycle runs, confirming the promising practical application. Based on the experimental results, a possible mechanism of decomposition of MB by the ZnAl-CLDH/ZIF-8 heterojunction was proposed.

This study reports that the novel binary g-C3N4@NiFe-LDH heterostructured photocatalysts were simply prepared by loading well-dispersed g-C3N4 nanosheets on the surface of NiFe-LDH precursor via the hydrothermal synthesis process. The morphologic structure, chemical composition and optical properties of the as-prepared nanocomposites were clearly characterized by using XRD, SEM, FT-IR, UV–Vis DRS, XPS and N2 adsorption–desorption techniques. In the photocatalytical degradation experiments, it can be seen that the optimal g-C3N4@NiFe-LDH nanocomposites can achieve the highest degradation efficiency (99%) for rhodamine B (RhB) within 240 min under visible light irradiation, and the corresponding pseudo-first-order rated constant is 0.912 h−1. The improvement of photocatalytical performance can be attributed to the enhanced visible light absorption and fast separation of the photo-generated electron–hole pairs. Besides, the degradation efficiency can still remain more than 80% via four cycle processes, demonstrating its remarkable stability and reusability. More importantly, a possible Z-scheme photocatalytic mechanism was proposed according to the analysis of energy band structure and the radicals trapping experiments. This study will be beneficial for the design and research of Z-scheme g-C3N4-based heterojunction photocatalysts in the environmental remediation field.

A visible-light-responsive hybrid photocatalyst, the BiOI/calcined ZnCo-layered double hydroxides (BiOI/ZnCo-CLDH), has been prepared via hydrothermal method. The property of samples was characterized by XRD, SEM, FT-IR, UV-vis and XPS, respectively. The photocatalytic activity of BiOI/ZnCo-CLDH was investigated by photodegradation of rhodamine B (RhB) and tetracycline hydrochloride (TCH) under visible light. The BiOI/ZnCo-CLDH hybrid photocatalyst which contains ZnCo-CLDH with mass fraction of 5wt% (BiOI/CLDH-3) shows the best degradation efficiency of RhB and TCH. The degradation efficiency of RhB (10 mg/L) can be achieved to 99.73 % in 40 min and the degradation efficiency of TCH (20 mg/L) can be achieved to 86.60 % in 90 min. Furthermore, the capture experiment demonstrates that h+ and ·OH are the primary active substance and the auxiliary active substance in the system of reaction, respectively. After five degradation experiments, the degradation efficiency of RhB and TCH by the composites can still achieve to 86 % of its initial activity, proving that the composites have remarkable reusability and stability.

The g-C3N4-based heterojunction photocatalysts have aroused worldwide attention for improving photogenerated charge carrier’s lifetime and photocatalytic activity. In this study, a series of CuWO4/g-C3N4 composites were prepared by a simple hydrothermal method, and then its structural characteristics were analyzed using XRD, SEM, FT-IR, UV–vis DRS, XPS, and N2 adsorption–desorption techniques. The photocatalytical activities of CuWO4/g-C3N4 composites were clearly evaluated by the photodegradation experiments of rhodamine B (RhB). The obtained results shown that CuWO4/g-C3N4 composite with the mass ratio of 10% CuWO4 displayed the highest degradation efficiency (93%) for RhB within 150 min in the photodegradation processes, which corresponded well with the pseudo-first-order kinetics. Obviously, the construction of Z-scheme CuWO4/g-C3N4 heterojunction can effectively improve photocatalytical efficiency, which is owing to fast separation of electron–hole pairs and enhancement of redox ability. Besides, the photodegradation efficiency can still keep more than 80% after four cycles, and then the reaction mechanism of photocatalysis was fully discussed to prove the formation of Z-scheme system. This work provides a certain theoretical foundation for the designation and research of g-C3N4-based Z-scheme heterojunction photocatalyst.

In this work, SnWO4/ZnFe-layered double hydroxide (LDH) composites were prepared by a simple hydrothermal method. The as-prepared products were characterized by XRD, SEM, TEM, EDX, FT-IR, XPS, UV–Vis DRS, and N2 adsorption–desorption techniques, which confirmed the successful synthesis and the excellent optical properties of the composites. In addition, the photocatalytic properties of the SnWO4/ZnFe-LDH composites are tightly related to the mass ratio of SnWO4 and LDH. When loaded with 5% ZnFe-LDH, the photocatalytic degradation efficiency of SnWO4/ZnFe-LDH composites for methyl orange (MO) reached 95.14% within 40 min under visible light irradiation. The enhanced photocatalytic activity of SnWO4/ZnFe-LDH composites could be attributed to the concerted photocatalysts effect between two components. Based on various characterization and experimental results, a possible photocatalytic mechanism was proposed. Furthermore, the resultant catalysts possess remarkable reusability and stability in five successive cycles. The SnWO4/ZnFe-LDH composites are expected as a promising catalyst for practical water purification and provide new ideas in the field of photocatalysis.

In this work, novel ZnS nanosheet was synthesized by using ZnAl-layered double hydroxide template for UV-light-driven photocatalytic degradation of tetracycline pollutant. The morphology, structure and UV light capacity of the obtained materials were characterized by XRD, SEM, TEM, HRTEM, EDS, FT-IR, UV–vis DRS, XPS, EIS Nyquist plots and PL spectrum, respectively. The results demonstrated that the as-synthesized ZnS nanosheet maintained layered structure and revealed the better photocatalytic activity than that of other materials toward tetracycline pollutant. The photocatalytic degradation efficiency of tetracycline pollutant was 85.73% under UV light irradiation using 500 W mercury lamp in 80 min, which was 1.53 times higher than that of pure ZnS microspheres. Besides, the as-prepared ZnS nanosheet exhibited higher stability and reusability after four runs. Eventually, a possible photodegradation mechanism was presented according to free radical trapping experiment. In addition, this work provided some references for the synthesis of related new photocatalytic materials.

Sulfate radicals (SO4 −)-based advanced oxidation processes have obtained far-reaching attention due to their high catalytic activity and selectively for intricate water environmental pollutants. The couple of cheap and readily available iron-based materials and peroxymonosulfate (PMS) or persulfate (PS) is an effective measure to generate incalculabe reactive sulfate radicals. The article analyzed the latest research progress on different typical heterogeneous iron-based catalysts for PMS or PS activation. The microstructure and electrical properties of these catalysts and the effects of different tailoring engineering approaches (such as structure defect, heteroatom doping, and rugulation of pore structure, etc) in PMS or PS activation were summarized. In addition, the environmental factors of iron-based materials-PMS (PS) systems in organic pollutants degradation and related advanced oxidation processes were also summarized. Finally, critical discussion and possible future prospects on challenges related to degradation mechanism exploration, potential catalysts development as well as practical catalytic system application were also proposed.