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In the social context of increasing water pollution, we conducted an in-depth study to prepare ZnFe2O4@g-C3N4 heterojunction nanocomposites by hydrothermal method. The microscopic morphology and structure were analyzed using XRD, SEM, TEM, UV–Vis, and other characterization methods. The photo-Fenton activity of the highly concentrated antibiotic tetracycline was tested under visible light irradiation in combination with the presence of H2O2, and the catalytic mechanism was investigated. The results showed that the construction of heterojunction significantly improved the catalytic activity of ZnFe2O4@g-C3N4 catalyst prepared by hydrothermal method. The degradation rate of tetracycline at 40 mg L−1 was 92.6% within 60 min, and the degradation rate was 0.06 min−1, which was nearly six times higher than that of pure ZnFe2O4. The results of free radical trapping experiments and electron spin resonance technique indicated that hydroxyl radicals (·OH) and superoxide radicals (·O2−) played important roles in the photo-Fenton degradation of tetracycline. Notably, the catalyst maintained a high degradation rate (87.2%) after five cycles. The heterojunction designed in this thesis may provide a promising strategy for achieving maximum light absorption and is authoritative in meeting environmental requirements in the future. [ABSTRACT FROM AUTHOR]

Flower-shaped BiOI@SnS2 nanocomposites were synthesized by the coprecipitation method. The effects of different composite ratios on the chemical composition, microstructure, morphology, optical properties, photoelectric chemical properties and photocatalytic properties of the samples were discussed. And the photocatalytic performance of the samples were evaluated by the photodegradation of Rhodamine B (RhB) in an aqueous solution under the xenon lamp. The experimental results demonstrated that BiOI@SnS2 nanocomposites were three-dimensional nanoflower-like microsphere structures with good crystallization. BiOI@SnS2 nanocomposites can improve visible light absorption due to their larger specific surface area and optimized energy band structure. BiOI@SnS2 heterojunction can effectively broaden the light visible light response range, accelerate the separation of photogenerated carriers and inhibit the recombination of electron-hole pairs. BiOI@SnS2 Z-scheme heterojunction exhibit excellent photocatalytic activity compared with pure BiOI and SnS2 photocatalysts in the degradation of RhB and the photocatalytic degradation rate of BiOI@SnS2-2 reached 76.8% after 90 min. In addition,.O2− and OH as the main active species in the photocatalytic degradation of RhB. [ABSTRACT FROM AUTHOR]

Reasonable construction of multi-pore heterogeneous structures and enhancement of synergistic interaction between metal ions are important means to improve the performance of supercapacitors. This work selected metal organic frameworks (MOF) as the sacrificial template, and Se-doped needle-like nanosphere heterostructures Se-CoSe 2 @ZnSe were successfully prepared by in situ growth and selenization treatment. The specific capacity of the Se-CoSe 2 @ZnSe-5 (CZS-5) electrode is up to 2469.12 F g−1 at 1 A g−1, and the capacity retention rate of 3000 cycles at a current density of 10 A g−1 is 85.39 %. The CZS-5//AC hybrid supercapacitor has a high power density of 1280.00 W kg−1 at an energy density of 68.88 Wh kg−1. The excellent electrochemical properties are attributed to the construction of Se-CoSe 2 @ZnSe heterostructure of needle-shaped nanospheres enhances the synergy between Zn and Co ions; the doping of selenium effectively improves the conductivity of the electrode material; selenium vacancies produced during selenization increase the activity of the active site. In addition, the density functional theory (DFT) calculation shows that Se-CoSe 2 @ZnSe-5 has higher density of states (DOS) near the Fermi energy level, which provides additional theoretical support for the improvement of electrochemical performance. • Se-CoSe 2 @ZnSe is needle-like nanosphere with ZIF-8 as the core, which can effectively alleviate structural collapse. • Se-CoSe 2 @ZnSe heterojunction structure effectively promotes charge rearrangement and builds internal electric field. • The selenium-rich structure effectively improves the electrical conductivity and the electron/ion transfer rate. • DFT provides theoretical support for the improvement of electrochemical performance. [ABSTRACT FROM AUTHOR]

• Magnetically separable MnFe 2 O 4 nanoparticles are synthesized onto SnS 2 microflowers to fabricate a Z-scheme MnFe 2 O 4 @SnS 2 heterojunction. • The MnFe 2 O 4 @SnS 2 -2 composite photocatalyzes 92.08 % degradation of MB at 120 min under pH = 9 and 1.5 mL H 2 O 2. • MnFe 2 O 4 @SnS 2 heterojunction possesses the widened band gap and weakened luminescence. • OH is the main active specie in photo-Fenton degradation. The novel MnFe 2 O 4 /CeO 2 /SnS 2 (1:0.2:0.5, 1:0.2:1, 1:0.2:1.5) nano-photocatalysts with magnetic recyclability were prepared via a facile hydrothermal route. MnFe 2 O 4 and CeO 2 nanoparticles are decorated onto SnS 2 flowers to fabricate a MnFe 2 O 4 /CeO 2 /SnS 2 ternary heterojunction. SnS 2 is an excellent connector between MnFe 2 O 4 and CeO 2 in synthesized MnFe 2 O 4 /CeO 2 /SnS 2 composite with a suitable band gap to accelerate methylene blue (MB) of photodegradation, which is attributed to its highly efficient separation of photogenerated electron-hole pairs. Compared with pure MnFe 2 O 4 , the photo-Fenton degradation of the MnFe 2 O 4 /CeO 2 /SnS 2 composites significantly enhance in the presence of H 2 O 2. Notably, the MnFe 2 O 4 /CeO 2 /SnS 2 (1:0.2:1) composite displays a slightly decreased charge-transfer resistance and an increased photocurrent density with good cycling stability after five runs, exhibiting the excellent photocatalytic and photo-Fenton performance under simulated sunlight. Consequently, the photo-Fenton mechanism of MnFe 2 O 4 /CeO 2 /SnS 2 is explained on the basis of coexistence of Mn2+/Mn3+ and Fe3+/Fe2+ redox couples. Meanwhile, OH is the main active specie. [ABSTRACT FROM AUTHOR]

Ag2S quantum dots were dispersed on the surface of SnS2 nanoflowers forming a heterojunction via in-situ ion exchange to improve photocatalytic degradation of RhB. All samples exhibit the hexagonal wurtzite structure. The size of Ag2S@SnS2 composites are ~ 1.5 μm flower-like with good crystallinity. Meanwhile, the Eg of 3% Ag2S@SnS2 is close to that of pure SnS2. Consequently, the 3% Ag2S@SnS2 composite displays the excellent photocatalytic performance under simulated sunlight irradiation with good cycling stability, compared to the pure SnS2 and other composites. Due to the blue and yellow luminescence quenching, the photogenerated electrons and holes is effectively separated in the 3% Ag2S@SnS2 sample. Especially, the hydroxyl radicals and photogenerated holes are main active species. [ABSTRACT FROM AUTHOR]