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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]

Based on the fact that the photo-Fenton process can directly use solar energy to degrade various pollutants, it has received widespread attention. However, it has attracted widespread attention due to the rapid recombination of photo-generated carriers and the low light response range. Therefore, the construction of a Z-scheme heterojunction in this paper can effectively enhance the electron–hole separation, increase the reduction and oxidation potential, and enhance the redox capability of the photocatalysis. This paper reports the successful preparation of visible-light-induced ZnFe2O4/BiOI composite photocatalysis. There is a Z-scheme heterojunction structure of ZnFe2O4 and BiOI. At the same time, the PL and UV absorption spectra showed that the light absorption performance of the composite nanomaterials was enhanced, the photo-generated carrier recombination rate was reduced, and the photo-Fenton performance was also significantly improved. And the photocurrent of ZnFe2O4/BiOI is more than 27 times that of pure ZnFe2O4. In addition, ZnFe2O4/BiOI can degrade the simulated pollutant RhB 100% within 20 min under simulated sunlight. It shows that ZnFe2O4/BiOI binary composite has excellent photo-Fenton properties. In addition, ZnFe2O4/BiOI still maintains a high photo-Fenton ability after three cycles. Therefore, it has potential application prospects of the industrial photodegradation of organic pollutants. [ABSTRACT FROM AUTHOR]

• BiOI is an excellent connector between ZnFe 2 O 4 and AgI to form a double Z-type heterojunction structure ZnFe 2 O 4 /BiOI/AgI composite through precise electronic regulation. • The existence of a double Z-heterojunction structure and Ag0 makes the electrons on the interface transfer and separate effectively. • Rich oxygen vacancies also provide more active sites for photocatalysis and photo-Fenton process. As a bridge, BiOI nanosheets connect ZnFe 2 O 4 nanoparticles and AgI clusters (∼300 nm) via hydrothermal-coprecipitation. A ternary composite with a double Z-type heterojunction structure is obtained through precise electronic regulation. Compared with ZnFe 2 O 4 and ZnFe 2 O 4 /BiOI, the photo-Fenton degradation RhB of ZnFe 2 O 4 /BiOI-AgI-3 samples is obviously improved under simulated sunlight. Rich oxygen vacancies also provide more active sites for photocatalysis and photo-Fenton process. The main active specie in photo-Fenton degradation is ·OH. The existence of a double Z-heterojunction structure and Ag0 makes the electrons on the interface transfer and separate effectively. Notably, the intensity of PL luminescence ZnFe 2 O 4 /BiOI/AgI is lower than that of ZnFe 2 O 4 and ZnFe 2 O 4 /BiOI because of reducing the recombination rate of photogenerated carriers. ZnFe 2 O 4 /BiOI/AgI composites have excellent stability of photo-Fenton degradation. Furthermore, the formation of a built-in electric field inhibits the recombination of electron-hole pairs, enhances visible light absorption, results in improving the efficiency of ternary composite materials to degrade pollutants. [Display omitted] [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]

The binary flower-like BiOI/CoFe 2 O 4 photocatalysts with magnetic retrievability were successfully synthesized via coprecipitation method. The effects of composite ratio on the microstructure, morphology, optical, photo-electrochemical and photocatalytic properties of the samples were studied. The experimental results show that BiOI/CoFe 2 O 4 nanocomposites contain tetragonal structure BiOI and cubic spinel structure CoFe 2 O 4 with good crystallization. Spherical CoFe 2 O 4 nanoparticles are uniformly decorated on the surface of BiOI nanosheets to establish hierarchical flower-like 3D- BiOI/CoF 2 O 4 heterojunctions. BiOI/CoFe 2 O 4 nanocomposites show excellent visible light absorption ability. PL spectra show the intensity decrease for BiOI/CoFe 2 O 4 nanocomposites. BiOI/CoFe 2 O 4 nanocomposites can promote the separation of photon-generated carriers, improve the migration efficiency, and improve the redox activity of nanocomposites. BiOI/CoFe 2 O 4 nanocomposites exhibit better photocatalytic activity during the process of degrading the RhB dye solution under the irradiation of simulated visible light. The degradation efficiency of BiOI/CFO-3 photocatalysts is 80.24% after 3 cycles, and exhibit better recyclable stability. Also, ·O 2 − is the main reactive species in the degradation process, which plays a crucial role in the RhB degradation. Image 1 • The binary flower-like BiOI/CoFe 2 O 4 photocatalysts with magnetic retrievability were synthesized via coprecipitation method. • BiOI/CoFe 2 O 4 nanocomposites show excellent visible light absorption ability. • BiOI/CoFe 2 O 4 nanocomposites accelerate the separation and migration efficiency of carriers, and improve the redox activity. • BiOI/CFO -3 samples have the best photocatalytic performance, and the degradation efficiency is 80.24% after 3 cycles. [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 magnetically separable MnFe 2 O 4 nanoparticles (15–50 nm) are synthesized onto SnS 2 microflowers (diameter 1–1.5 μm, thickness 50 nm), fabricating a direct Z-scheme MnFe 2 O 4 @SnS 2 heterojunction nanocomposite via two-step hydrothermal. The MnFe 2 O 4 @SnS 2 composites with an appropriate SnS 2 content exhibit enhanced photo-Fenton degradation performances to make efficient separation of photoexcited electron/hole pairs. In the photo-Fenton degradation tests, MnFe 2 O 4 @SnS 2 -2 shows excellent performance that 92.08 % of methylene blue (MB) could be photocatalyzed within120 min with pH = 9 and 1.5 mL H 2 O 2 , which is about 2.43 times than that of bare MnFe 2 O 4 nanoparticles. In general, the Mn2+ and Fe2+ in-situ regenerated through accepting electrons from the cathode as the result of the Z-scheme electron transfer. Moreover, over 88 % of MB is still removed in the 5th run is attributed that SnS 2 driven also extend the longevity of the MnFe 2 O 4 catalyst. Different capture agents IPA, BQ and TEOA investigation displays that ·OH is the main active specie. [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]

• A surface molecularly imprinted Z-type heterojunction composite photocatalyst was synthesized. • Photocatalytic materials can specifically recognize ceftriaxone sodium in water and preferentially adsorb it for photocatalytic degradation. • The selectivity depends on the holes with specific recognition ability on the surface of molecularly imprinted photocatalyst. • Molecularly imprinted photocatalyst has high stability and excellent reusability. By using the surface molecular imprinting technique, BiOCl/Bi 3 NbO 7 was used as the substrate photocatalyst and ceftriaxone sodium (CTRX) was used as the template. A molecularly imprinted photocatalyst with specific recognition and photocatalytic synergy for CTRX was synthesized. Due to the excellent photoelectric properties and the successful formation of CTRX-imprinted cavities on the imprinted layer surface. The characterization results showed that MIP-3 has the advantages of uniform particle size and high separation efficiency of photogenerated carriers. The molecularly imprinted photocatalyst MIP-3 showed remarkable synergy and selectivity in both adsorption-photocatalysis of CTRX. Further experimental results showed that MIP-3 exhibited high selective adsorption performance for both high and low concentrations of CTRX in the 30 min static adsorption experiment. About 92 % of CTRX was degraded in the 100 min light experiment, which was a large improvement compared with BiOCl/Bi 3 NbO 7. The selectivity of MIP-BNO was evaluated by comparing the degradation efficiency of MIP-3 on CTRX and chloramphenicol (CIP). Compared to non-imprinted photocatalyst NIP-BNO, MIP-3 has a higher selectivity coefficient of 2.58 and a faster degradation kinetic rate of 0.0169 min−1. The stability experiments showed that MIP-3 has good recoverability and stability during photocatalytic degradation. The mechanism of selective photocatalytic degradation of CTRX by MIP-3 was investigated by UV–visible spectroscopy, radical capture experiments, and electron spin tests. The possible degradation pathway of CTRX was also analyzed by LC-MS. In conclusion, this study confirms that the combination of surface molecular imprinting and photocatalyst has great potential to provide a promising solution for the treatment of low-level, highly toxic target pollutants in mixed wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Z-scheme Bismuth iodide/Bismuth niobate heterojunction was synthesized. • Photodegradation activity was rely on the interface structure of the photocatalyst. • Interface was continuously transitional with a proper molar ratio of the Nb and Bi. • DFT analysis and the Fukui index was used to explore the degradation pathway. A direct Z-scheme bismuth iodide/bismuth niobate (BiOI/BiNbO) heterojunction photocatalysts with a different molar ratio of Bi/Nb were prepared. The structural and photoelectrical properties of these as-prepared samples were investigated, photocatalytic activity and different effect factors were evaluated. The experiment results indicated that the highest RhB degradation efficiency was that of the sample with Bi/Nb = 0.7, bringing a lower interface resistance that facilitate the separation and transportation of photogenerated carrier. Furthermore, active species trapping experiments suggested that •OH was the most contributor responsible for the RhB photocatalytic process. The photodegradation mechanism and a reasonable degradation pathway were further proposed by DFT theoretical calculation. [ABSTRACT FROM AUTHOR]