Synthesis of magnetic layered double hydroxide (Fe3O4@CuCr-LDH) decorated with ZIF-8 for efficient sonocatalytic degradation of tetracycline

A series of Fe3O4@CuCr-LDH hybrids decorated with different amount of ZIF-8 (FLZ, 10-40 wt%) was prepared using simple methods and characterized with different techniques. The activity of the synthesized nanocomposites was investigated in the sonocatalytic degradation of tetracycline (TC) antibiotic from wastewater. When the content of ZIF-8 in the nanocomposite structure was 20 wt%, the FLZ-20 sonocatalyst exhibited the high performance in the sonocatalytic removal of TC. At optimum conditions (0.7 g/L catalyst dosage, pH of 7, 50 mg/L initial concentration of antibiotic, and 15 min sonication time) of the sonocatalytic removal of TC approached to 91.4% under ultrasonic irradiation (USI) using FLZ-20. This efficiency was much higher than those of obtained results by Fe3O4@CuCr-LDH and pristine ZIF-8. The formed ●OH and ●O2- exhibited the major roles in the sonocatalytic TC degradation process. The excellent performance of FLZ-20 can be attributed to the heterojunctions created between composite components, which could improve the electron transfer ability and effectively separate e-/h+ pairs. In addition, FLZ-20 showed the superior reusability and stability during three successive recycling. Moreover, the facile magnetically separation of the sonocatalyst from the aqueous solution was another outstanding feature, which prevents the formation of secondary pollutants. It can be concluded that the fabrication of heterojunctions is an efficient procedure to promote the sonocatalytic acting of the catalyst.

ZIF-8/g-C3N4 photocatalysts: enhancing CO2 reduction through improved adsorption and photocatalytic performance

Nowadays, the widespread concern over controlling CO2 emissions and mitigating the adverse effects of greenhouse gases on global climate has attracted significant attention. In this study, g-C3N4 was synthesized by thermopolymerizing urea. Subsequently, ZIF-8 was combined with g-C3N4 using an in situ deposition method, resulting in the fabrication of ZIF-8/g-C3N4 composite photocatalysts at various molar ratios. Effective incorporation of ZIF-8 into g-C3N4 suppressed the recombination of photogenerated electrons and holes, thereby enhancing CO2 capture capacity and preserving light absorption capabilities. The ZIF-8/g-C3N4 composite demonstrates excellent photocatalytic performance for CO2 reduction, where the optimized material exhibited a CO2 adsorption capacity 1.52 times that of pure g-C3N4 and increased the conversion of CO2 to CH4 by more than sevenfold. This study harnesses the superior CO2 adsorption properties of metal-organic frameworks to develop more efficient photocatalysts, enhancing CO2 conversion efficacy and offering insights for developing efficient photocatalysts that utilize CO2.

Bimetal doped Cu-Fe-ZIF-8/g-C3N4 nanocomposites for the adsorption of tetracycline hydrochloride from water

Bimetal doped Cu-Fe-zeolitic imidazole framework-8 (ZIF-8)/graphitic carbon nitride (GCN) (Cu-Fe-ZIF-8/GCN) nanocomposites were prepared via one-pot and ion-exchange methods. The main influencing factors, such as adsorbent concentration, TC concentration, initial pH, and coexisting ions, were evaluated in detail. Due to the suitable pore structures and the presence of multiple interactions on the surface, the nanocomposite showed a high adsorption capacity up to 932 mg g-1 for tetracycline hydrochloride (TC), outperforming ZIF-8 by 4.8 times. The adsorption kinetics and adsorption isotherm were depicted in good detail using pseudo-second-order kinetic and Langmuir models, respectively. Thermodynamic calculation revealed that the adsorption of the nanocomposite under experimental conditions was a spontaneous heat absorption process, and was primarily driven by chemisorption. After four cycles of use, the nanocomposite retained 87.2% of its initial adsorption capacity, confirming its high reusability and broad application prospects in removing tetracycline-type pollutants from wastewater.

A review of metal-organic framework (MOF) materials as an effective photocatalyst for degradation of organic pollutants

Water plays a vital role in all aspects of life. Recently, water pollution has increased exponentially due to various organic and inorganic pollutants. Organic pollutants are hard to degrade; therefore, cost-effective and sustainable approaches are needed to degrade these pollutants. Organic dyes are the major source of organic pollutants from coloring industries. The photoactive metal-organic frameworks (MOFs) offer an ultimate strategy for constructing photocatalysts to degrade pollutants present in wastewater. Therefore, tuning the metal ions/clusters and organic ligands for the better photocatalytic activity of MOFs is a tremendous approach for wastewater treatment. This review comprehensively reports various MOFs and their composites, especially POM-based MOF composites, for the enhanced photocatalytic degradation of organic pollutants in the aqueous phase. A brief discussion on various theoretical aspects such as density functional theory (DFT) and machine learning (ML) related to MOF and MOF composite-based photocatalysts has been presented. Thus, this article may eventually pave the way for applying different structural features to modulate novel porous materials for enhanced photodegradation properties toward organic pollutants.

SiC@FeZnZiF as a Bifunctional Catalyst with Catalytic Activating PMS and Photoreducing Carbon Dioxide

Herein, we encapsulated modified silicon carbide nanoparticles utilizing a metal-organic backbone. E-SiC-FeZnZIF composites were successfully prepared via Fe doping. The catalysis activity of this bifunctional composite material was evaluated by the degradation of tetracycline (THC) and carbamazepine (CBZ) and the reduction of carbon dioxide (CO₂). Nano SiC has received widespread attention in advanced oxidation applications, especially in the catalytic activation of peroxymonosulfate (PMS). However, the inferior activity of SiC has severely restricted its practical use. In this study of dual functional composite materials, nano SiC was firstly etched under aqueous alkali. Then, zeolite imidazolate frame-8 (ZIF-8) was used for immobilization. The filling of the etched nano SiC with FeZnZiF was confirmed by SEM, XRD, FTIR, BET, and XPS analyses. In addition, E-SiC-FeZnZIF exhibited excellent catalytic activation of peroxymonosulfate (PMS) to oxidize water pollutants, which can degrade tetracycline hydrochloride (THC), achieving a removal rate of 72% within 60 min. Moreover, E-SiC-FeZnZIF exhibited a relatively high CO₂ reduction rate with H₂O. The yields of CO and CH₄ were 0.085 and 0.509 μmol g^-1, respectively, after 2 h, which are higher than that of 50 nm of commercial SiC (CO: 0.084 μmol g^-1; CH₄: 0.209 μmol g^-1). This work provides a relatively convenient synthesis path for constructing metal skeleton composites for advanced oxidation and photocatalytic applications. This will have practical significance in protecting water bodies and reducing CO₂, which are vital not only for maintaining the natural ecological balance and negative feedback regulation, but also for creating a new application carrier based on nano silicon carbide.

CdTe QDs-sensitized TiO2 nanocomposite for magnetic-assisted photoelectrochemical immunoassay of SARS-CoV-2 nucleocapsid protein

A sensitive, reliable, and cost-effective detection for SARS-CoV-2 was urgently needed due to the rapid spread of COVID-19. Here, a "signal-on" magnetic-assisted PEC immunosensor was constructed for the quantitative detection of SARS-CoV-2 nucleocapsid (N) protein based on Z-scheme heterojunction. Fe₃O₄@SiO₂@Au was used to connect the capture antibody to act as a capture probe (Fe₃O₄@SiO₂@Au/Ab₁). It can extract target analytes selectively in complex samples and multiple electrode rinsing and assembly steps were avoided effectively. CdTe QDs sensitized TiO₂ coated on the surface of SiO₂ spheres to form Z-scheme heterojunction (SiO₂@TiO₂@CdTe QDs), which broadened the optical absorption range and inhibited the quick recombination of photogenerated electron/hole of the composite. With fascinating photoelectric conversion performance, SiO₂@TiO₂@CdTe QDs were utilized as a signal label, thus further realizing signal amplification. The migration mechanism of photogenerated electrons was further deduced by active material quenching experiment and electron spin resonance (ESR) measurement. The elaborated immunosensor can detect SARS-CoV-2 N protein in the linear range of 0.005-50 ng mL^-1 with a low detection limit of 1.8 pg mL^-1 (S/N = 3). The immunosensor displays extraordinary sensitivity, strong anti-interference, and high reproducibility in detecting SARS-CoV-2 N protein, which envisages its potential application in the clinical diagnosis of COVID-19.

Photocatalytic removal of toxic dyes, liquorice and tetracycline wastewaters by a mesoporous photocatalyst under irradiation of different lamps and sunlight

Simple recyclable K₅CoW₁₂O₄₀/TiO₂ was synthesized and used to remove methyl orange, rhodamine B, direct red 16 and crystal violet toxic organic dyes, liquorice industrial wastewater and tetracycline (TC) as an antibiotic. Photoactivity of the catalyst was checked out under irradiation of various lamps (such as 18 W fluorescent, 300 W Xenon, LED and IR lamps). The best efficiency was obtained by fluorescent lamp at catalyst loading of 3 g/L, initial pH of 5, initial dye concentration of 5 ppm, complete degradation was achieved after 30 min contact time. Mechanistic investigation showed that·O₂ radicals and h⁺ are majorly responsible for photodegradation in this process. Electrochemical investigation, Nyquist, Bode, Mott-Schottky, Tauc plots and photoluminescence proved that using this photocatalyst delay the electron-hole recombination, increase the lifetime of excited electron, extend light absorption to visible region and improve the light absorption capacity. This photocatalyst work well under winter sunlight. Also 97% and 84% dye removal was obtained for liquorice with 300 and 1000 COD at optimal condition. This catalyst showed similar activity for TC wastewater. Photocatalyst was characterized by FE-SEM, EDX, AFM, FT-IR, XRD, PL, DRS, EIS, BJH and BET.

One-pot hydrothermal synthesis of a double Z-scheme g-C3N4/AgI/β-AgVO3 ternary nanocomposite for efficient degradation of organic pollutants and DPC-Cr(VI) complex under visible-light irradiation

The Z-scheme photocatalytic system provides a promising way to achieve significant photodegradation efficiency. The work embodied here describes the synthesis of highly efficient double Z-scheme g-C₃N₄/AgI/β-AgVO₃ (g-CNAB) ternary nanocomposite using a one-pot hydrothermal route. The optical properties, phase structure, and morphology of the synthesized samples were investigated using UV-visible diffuse-reflectance spectroscopy (UV-Vis DRS), X-ray diffraction, and scanning electron microscopy, respectively. The transmission electron microscopy investigation revealed that synthesized composite material represents close interfacial interactions. X-ray photoelectron spectroscopy analysis confirms the presence of all the elements in the synthesized ternary nanocomposite materials. The photocatalytic performance of as-prepared photocatalysts has been systematically investigated using the photodegradation of a variety of pollutants, including Rhodamine B, Ciprofloxacin, and 1,5-diphenylcarbazide-Cr(VI) [DPC-Cr(VI)] complex under visible-light irradiation. Among all synthesized materials, such as g-C₃N₄, AgI, β-AgVO₃, and ternary nanocomposites with varying loading of β-AgVO₃ [g-CNAB_{(0.5, 1.0, 1.5, 2.0)}], the photocatalyst g-CNAB_(1.5) nanocomposite achieved a remarkably high photocatalytic efficiency. The quenching impact of several scavengers revealed that reactive species such as superoxide anion radical (O₂^·-) and hydroxyl radical (·OH) are significant in the degradation of various contaminants. Based on the characterization and application, a plausible photocatalytic mechanism has been sketched out to determine the reaction pathways involved in the degradation of pollutants present in the aqueous medium.

Artificial Nanoplatelets Depend on Size for Precisely Inducing Thrombosis in Tumor Vessels

Due to the heterogeneity of a tumor, the tumor vascular interruption-based therapy has become an ideal treatment strategy. Herein, artificial nanoplatelets are reported to induce selective thrombosis in tumor vessels, which can achieve rapid and large-scale necrosis of tumor cells. For one, the nanoplatelets are exploited to specially release thrombin into target regions without affecting the established coagulation factors system. For another, the thrombin elicits vascular infarction to provide tumor-ablation effects. More importantly, the size-dependent effect of nanoplatelets (with diameters of 200, 400, and 800 nm) in vivo on blocking the tumor vessels is evaluated. The results show that the nanoplatelets from nanometer to submicron have achieved different biodistribution and therapeutic effects through the vascular transport. Notably, 400 nm scale nanoplatelets can induce thrombosis in tumor vessels and achieve 83% of the tumor elimination rate, thus manifesting the effectiveness of anti-tumor strategy compared with the other two scales of nanoplatelets (200 and 800 nm). These findings highlight the need of concern about nanoparticle size, providing a promising strategy for the future design of advanced vascular targeting reagents and the clinical translation of tumor vascular interruption-based therapy.

Interfacial band bending induced charge-transfer regulation over Ag@ZIF-8@g-C3N4 to boost photocatalytic CO2 reduction into syngas

The use of the AZC-10 heterostructure enables excellent syngas production rates of 4076.4 μmol gcatalyst−1 h−1 and 3326.55 μmol gcatalyst−1 h−1 for CO and H2, respectively, much higher than other reported photocatalysts.

Controllably Electrodepositing ZIF-8 Protective Layer for Highly Reversible Zinc Anode with Ultralong Lifespan

Aqueous zinc-ion batteries with high safety and cost effectiveness have received much attention for large-scale energy storage. However, the inevitable dendrite growth derived from uneven zinc stripping/plating severely impedes practical application. In this work, we use controllable electrodeposition to construct a continuous and compact ZIF-8 protective layer and investigate the relationship between the morphology of the deposition layer and the zinc plating behavior. A continuous and insulating protective layer with suitable thickness can induce bottom deposition, and a prolonged battery life of over 5000 cycles at 10 mA cm^-2 for 1 mA h cm^-2 is achieved.

Engineering of g-C3N4-based photocatalysts to enhance hydrogen evolution

The technology of photocatalytic hydrogen production that converts abundant yet intermittent solar energy into an environmentally friendly alternative energy source is an attractive strategy to mitigate the energy crisis and environmental pollution. Graphitic carbon nitride (g-C₃N₄), as a promising photocatalyst, has gradually received focus in the field of artificial photosynthesis due to its appealing optical property, high chemical stability and easy synthesis. However, the limited light absorption and massive recombination of photoinduced carriers have hindered the photocatalytic activity of bare g-C₃N₄. Therefore, from the perspective of theoretical calculations and experiments, many valid approaches have been applied to rationally design the photocatalyst and ameliorate the hydrogen production performance, such as element doping, defect engineering, morphology tuning, and semiconductor coupling. This review summarized the latest progress of g-C₃N₄-based photocatalysts from two perspectives, modification of pristine g-C₃N₄ and interfacial engineering design. It is expected to offer feasible suggestions for the fabrication of low-cost and high-efficiency photocatalysts and the photocatalytic mechanism analyses assisted by calculation in the near future. Finally, the prospects and challenges of this exciting research field are discussed.

Novel SnO2@ZIF-8/gC3N4 nanohybrids for excellent electrochemical performance towards sensing of p-nitrophenol

Herein, a novel synthetic strategy has been proposed to prepare engineered SnO₂@ZIF-8/gC₃N₄ nanohybrids for electrochemical sensing of p-nitrophenol (p-NP). The electrochemical properties were investigated using cyclic voltammetry (CV), chronoamperometry (CA), and differential pulse voltammetry (DPV). The developed nanohybrid sensor displayed an excellent electrochemical performance towards sensing of p-NP with a detection limit of 0.565 μM. The sensitivity of the prepared nanohybrid was found to be 2.63 μAcm^-2μM^-1. Moreover, the newly fabricated sensor exhibited remarkable selectivity (over tenfold excess) in the presence of common interferents. The simultaneous detection of isomers of nitrophenol is difficult using the developed sensor. However, other common interferents, such as phenol and aminophenol have negligible effects on the sensitivity of SnO₂@ZIF-8/gC₃N₄ towards the detection of p-nitrophenol. Further, the newly developed sensor showed consistency of sensing response up to 30 days. Thus, implementation of SnO₂@ZIF-8/gC₃N₄ nanohybrids as a p-NP electrochemical sensor offers the advantages of simplicity, selectivity, and stability.

Metal–organic framework/carbon nitride nanosheets composites (TMU-49/CNNSs): efficient photocatalyst for aerobic oxidation of alcohols under visible light

The TMU-49/CNNSs composite was used as a photocatalyst for oxidation of alcohols.

The synergistic effect of Ag/AgCl@ZIF-8 modified g-C3N4 composite and peroxymonosulfate for the enhanced visible-light photocatalytic degradation of levofloxacin

In this work, a series of Ag/AgCl@ZIF-8 modified g-C₃N₄ composites were synthesized and used to degrade levofloxacin (LVFX) in water under visible light irradiation with the assistant of peroxymonosulfate (PMS). The morphologies and physicochemical properties of the materials were characterized by SEM, TEM, XRD, XPS, FTIR, and DRS technologies. The results of photocatalytic experiments showed that in the presence of PMS, the degradation rate of LVFX reached 87.3% in 60min. Furthermore, factors affecting photocatalytic efficiency such as the concentration of PMS, photocatalyst dosage and different pH values were investigated. The degradation products of LVFX were analyzed by LC-MS and the degradation pathway was inferred. Active species trapping experiments indicated that O₂^-, h⁺ and SO₄^- played important roles in the degradation process in the presence of PMS and the possible degradation mechanism was put forward. This work provides a photocatalyst system that is beneficial to the separation of photogenerated carriers and demonstrates the great potential of PMS-assisted photocatalysis in the purification of organic pollutants.

In situ growth of ZIF-8 nanoparticles on chitosan to form the hybrid nanocomposites for high-efficiency removal of Congo Red

The zeolitic imidazole framework (ZIF-8) dotted chitosan (CS) nanocomposites (ZIF-8@CS) were fabricated via in-situ growth method. The morphology, structure and chemical state of ZIF-8@CS were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform IR spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorption behavior of ZIF-8@CS composites on Congo Red (CR) in aqueous solution was systematically investigated. The adsorption isotherm data showed that the adsorption of CR by ZIF-8@CS was single-layer adsorption, which was consistent with the Langmuir isotherm model. The maximum adsorption capacity of ZIF-8@CS was 922 mg/g. The kinetics parameters were in accord with pseudo-second-order equation, which implied that the adsorption rate was mainly controlled by the chemisorption mechanism. The removal of CR was attributed to the participation of hydrogen bonds, electrostatic interactions, π-π conjugation and zinc coordination effects.

A Novel Bi₂MoO₆/ZIF-8 Composite for Enhanced Visible Light Photocatalytic Activity

A series of novel Bi₂MoO₆/zeolitic imidazolate framework-8 (ZIF-8) photocatalysts have been successfully fabricated through a facile self-assembly process. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectrophotometry, and X-ray photoelectron spectroscopy (XPS) characterized pure Bi₂MoO₆, pure ZIF-8, and a series of Bi₂MoO₆/ZIF-8 composites. The result indicated that, when compared with pure Bi₂MoO₆, the composite of Bi₂MoO₆/ZIF-8 exhibited excellent photocatalytic performance for the degradation of methylene blue (MB) under visible light. Moreover, the Bi₂MoO₆/ZIF-8-3 composite (the molar ratio of Bi₂MoO₆ to 2-MI is 3:3) has optimum photocatalytic performance because of the suitable amount of ZIF-8 decorated on the flower-like Bi₂MoO₆. The enhanced photocatalytic activity is probably due to the introduction of ZIF-8, which will promote the separation of electron–hole pair and the surface morphology. Benefitting from the diversity of the MOF species (ZIF-8 is one of them), this composing strategy of Bi₂MoO₆/MOF composite would provide new insight into the design of highly efficient visible light photocatalysts.

Surface conversion of ZnO nanorods to ZIF-8 to suppress surface defects for a visible-blind UV photodetector

ZnO nanomaterials are promising building blocks for an efficient UV photodetector; however, their slow sensing behavior and undesired response to visible light, which are attributed to surface defects, such as oxygen or zinc vacancies, are challenges that remain to be addressed. Here, we transformed the ZnO nanorod surface into a zeolitic imidazolate framework-8 (ZIF-8) to eliminate ZnO surface defects. Vertical-type photodetectors were fabricated incorporating a Schottky junction at the ZIF-8/gold (Au) top electrode and could respond to UV light with a rapid response and recovery (1-2 s) and demonstrated a UV-to-visible rejection ratio in the order of 10³, qualifying them as efficient visible-blind UV photodetectors. It is noteworthy that the ZIF-8 layer effectively separated the photogenerated electron-hole pairs, and thus reduced their recombination probability. The enhanced photodetector displayed excellent figures-of-merit: a responsivity of 291 A W^-1 and a detectivity of 5.9 × 10¹³ cm Hz^1/2 W^-1 under illumination at 295 nm.