ZIF-8 templated assembly of La3+-anchored ZnO distorted nano-hexagons as an efficient active photocatalyst for the detoxification of rhodamine B in water

Sulfur vacancy-rich bismuth sulfide nanowire derived from CAU-17 for radioactive iodine capture in complex environments: Performance and intrinsic mechanisms

Effective capture and immobilization of volatile radioiodine from the off-gas of post-treatment plants is crucial for nuclear safety and public health, considering its long half-life, high toxicity, and environmental mobility. Herein, sulfur vacancy-rich Vs-Bi2S3@C nanocomposites were systematically synthesized via a one-step solvothermal vulcanization of CAU-17 precursor. Batch adsorption experiments demonstrated that the as-synthesized materials exhibited superior iodine adsorption capacity (1505.8 mg g-1 at 200 °C), fast equilibrium time (60 min), and high chemisorption ratio (91.7%), which might benefit from the nanowire structure and abundant sulfur vacancies of Bi2S3. Furthermore, Vs-Bi2S3@C composites exhibited excellent iodine capture performance in complex environments (high temperatures, high humidity and radiation exposure). Mechanistic investigations revealed that the I2 capture by fabricated materials primarily involved the chemical adsorption between Bi2S3 and I2 to form BiI3, and the interaction of I2 with electrons provided by sulfur vacancies to form polyiodide anions (I3-). The post-adsorbed iodine samples were successfully immobilized into commercial glass fractions in a stable form (BixOyI), exhibiting a normalized iodine leaching rate of 3.81 × 10-5 g m-2 d-1. Overall, our work offers a novel strategy for the design of adsorbent materials tailed for efficient capture and immobilization of volatile radioiodine.

Construction of direct FeMoO4/g-C3N4-2D/2D Z-scheme heterojunction with enhanced photocatalytic treatment of textile wastewater to eliminate the toxic effect in marine environment

A novel FeMoO₄/g-C₃N₄-2D/2D Z-scheme heterojunction photocatalyst was prepared via wet chemical method. The observed structural morphology of FeMoO₄/g-C₃N₄ reveals the 2D-iron molybdate (FeMoO₄) nanoplates compiled with the 2D-graphitic carbon nitride (g-C₃N₄) nanosheets like structure. The photocatalytic activity of the g-C₃N₄, FeMoO₄, and FeMoO₄/g-C₃N₄ composites were studied via the degradation of Rhodamine B (RhB) as targeted textile dye under visible light irradiation (VLI). The optimal FeMoO₄/g-C₃N₄ (1:3 ratio of g-C₃N₄ and FeMoO₄) composite show an enhanced degradation performance with rate constant value of 0.02226 min^-1 and good stability even after three cycles. Thus, the h+ and O₂^•－are the key radicals in the degradation of RhB under VLI. It is proposed that the FeMoO₄/g-C₃N₄ Z-scheme heterojunction effectively enhances the transfer and separation ability of e^-/h⁺ pairs, by the way increasing the photocatalytic efficiency towards the RhB degradation. Thus, the newly constructed Z-scheme FeMoO₄/g-C₃N₄ heterojunction photocatalyst is a promising material for the remediation of wastewater relevant to elimination of toxic effect in marine environment.

Removal of toxic dye from dye-laden wastewater using a new nanocomposite material: Isotherm, kinetics and adsorption mechanism

In this study, (hemi)cellulosic biochar-based environment-friendly non-toxic nanocomposite (nAg-AC) was fabricated for an inordinate overlook of toxic dye-laden wastewater depollution. This hybrid nanocomposite grafted with silver nanoparticles, numerous hydroxyl and π-bond containing functional groups exhibited outstanding physicochemical properties. FESEM images indicated the heterogeneous porous structure of nAg-AC, while BET analysis revealed mesoporous property with a significant increment of overall surface area (132%). Imbedding of silver nanoparticles and the presence of multiple hydroxyl groups was evident from the XRD and XPS spectrum. Further, the TGA result indicated excellent thermal stability, and FTIR analysis suggested the involvement of surface functional groups like -OH, =C = O, =NH, =C = C = , and -CH in Rhodamine B (RhB) adsorption. The adsorbent matrix provided the overall mechanical strength and facilitated recycling, while the functional matrix (biochar) provided the adsorptive locus for augmented RhB adsorption efficiency (92.77%). Experiments pertaining to adsorption isotherms and kinetics modeling suggested that RhB was removed through multilayer chemisorption on the heterogeneous nAg-AC surface. The main RhB adsorption mechanism included cumulative efforts of H-bindings, π-π stacking interaction, pore-filling, and electrostatic interactions. The nAg-AC maintained mechanical robustness with significant RhB adsorption even after three consecutive regeneration cycles signifying facile recycling. The nAg-AC displayed an outstanding efficacy for the real industrial wastewater depollution, indicating high effectiveness for practical environmental applications. Finally, the cost analysis (incorporating economic, environmental, and social dimensions) suggested a significant role of the nAg-AC in promoting and establishing sustainable development with the circular economy.

Facile Synthesis of Copper-Coated-Reduced-Graphene-Oxide and Its Application as a Highly Sensitive Electrochemical Sensor for Hydroquinone

A facile step-by-step approach for synthesizing copper nanoparticles (CuNPs) loaded on the wrinkled surface of reduced-graphene-oxide (Cu/rGO) was conducted using a reductant at room temperature. Multiple characterization methods were applied to specify the morphology and composition of the nanocomposites. The scanning electron microscope and transmission electron microscope of Cu/rGO show that spherical CuNps were dispersed uniformly on the surface of rGO. In addition, the characteristic peaks of Cu and carbon in energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy analyses spectra proved that Cu/rGO nanocomposites were synthesized. Soon afterwards, a new hydroquinone electrochemical sensor was prepared with Cu/rGO and a glassy carbon electrode. The sensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Hydroquinone was detected by differential pulse voltammetry using the composite electrode. Under the optimal condition, the linear response range was from 0.05 μM to 90 μM; the detection limit is 0.02 μM (S/N = 3) for hydroquinone. The electrochemical sensor exhibited high sensitivity in practical environmental water sample detection.

Metal Organic Framework-Derived ZnO@GC Nanoarchitecture as an Effective Hydrogen Gas Sensor with Improved Selectivity and Gas Response

Although they are not as favorable as other influential gas sensors, metal-oxide semiconductor-based chemiresistors ensure minimal surface reactivity, restricting their gas selectivity, gas response, and reaction kinetics, particularly when functioning at room temperature (RT). A hybrid design, which includes metal-oxide/carbon nanostructures and passivation with specific gas filtration layers, can address the concerns of surface reactivity. We present a novel hierarchical nanostructured zinc oxide (ZnO), decorated with graphitic carbon (GC) and synthesized via a wet-chemical strategy, which is then followed by the self-assembly of a zeolitic imidazolate framework (ZIF-8). Because of its large surface area, high porosity, and efficient inspection of other analyte (interfering) gases, the ZnO@GC can provide intensified surface reactivity at RT. In the present study, such a hybrid sensor confirmed extraordinary gas sensing properties, which was characterized by excellent H₂ selectivity, fast response, rapid recovery kinetics, and high gas response (ΔR/R₀ ∼ 124.6%@10 ppm), particularly in extremely humid environments. The results reveal that adsorption sites provided by the ZIF-8 template-based ZnO@GC frameworks facilitate the adsorption and desorption of H₂.

Rational design of ZnO-zeolite imidazole hybrid nanoparticles with reduced charge recombination for enhanced photocatalysis

Semiconducting zinc oxide nanoparticles (ZnO NPs) hold great potential as photocatalysts in wastewater treatment because of their favorable bandgap and cost-effectiveness. Unfortunately, ZnO NPs usually show rapid charge recombination that limits their photocatalytic efficacy significantly. Herein, we report a facile way of modifying ZnO NPs with zeolite imidazole framework-8 (ZIF8). A synergy between the two components may tackle the drawback of fast charge recombination for pristine ZnO NPs. Improved performance of photocatalytic degradation of methylene blue (MB) is confirmed by comparing with pristine ZnO and ZIF8 as the catalysts. The ZIF8 in the composite serves as a trap for photogenerated electrons, thus reducing the rate of charge recombination to enhance the photocatalysis rate. In addition, the hybridization process suppresses the aggregation of ZnO NPs, providing a large surface area and a greater number of active sites. Moreover, a small shift in the absorption band of ZnO@ZIF8 (10) NPs towards higher wavelength, also witnessed a little contribution towards enhanced photocatalytic properties. Mechanistic studies of the photocatalytic process of MB using ZnO@ZIF8 NPs catalyst reveal that hydroxyl radicals are the major reactive oxygen species. The facile hybridization of ZnO with ZIF8 provides a strategy for developing new photocatalysts with wide application potential.

Unveiling the Redox Electrochemistry of MOF-Derived fcc-NiCo@GC Polyhedron as an Advanced Electrode Material for Boosting Specific Energy of the Supercapattery

Metal organic frameworks (MOFs), which constitute a new class of porous organic-inorganic hybrid materials, have gained considerable attention in the fields of electrochemical energy storage and conversion devices owing to their open topological structures, large surface areas, tunable morphologies, and extreme redox activity. A synthesis protocol that comprises coprecipitation followed by controlled calcination processes to design a battery-type electrode is used. This electrode consists of three-dimensional (3D), ant cave-like polyhedrons of nickel-cobalt alloy on graphitic carbon (GC; NiCo@GC) nanostructures; trimesic acid is used as a potential MOF-linker. The developed NiCo@GC sample exhibits mesoporous characteristics with the maximum surface area of 94.08 m² g^-1 at 77 K. In addition, the redox activity at different sweep rates reveals the battery-type charge storage behavior of the NiCo@GC electrode; its three-electrode assembly provides 444 C g^-1 specific capacity at 2 A g^-1 with long-term capacity retention. The constructed supercapattery (SC) devices (i.e., AC//NiCo@GC) achieved capacity, specific energy, and specific power are 74.3 mAh g^-1 , 39.5 Wh kg^-1 , and 665 W kg^-1 , respectively. Owing to its reasonable electrochemical characteristics, the prepared NiCo@GC material is a promising candidate for supercapattery electrodes for portable electronic devices.

Fabrication of nonenzymatic electrochemical sensor based on Zn@ZnO core-shell structures obtained via pulsed laser ablation for selective determination of hydroquinone

Herein, we fabricated a more sensitive nonenzymatic electrochemical sensor for the selective determination of hydroquinone as a targeted pollutant at zinc@zinc oxide (Zn@ZnO) core-shell nanostructures. The nanostructured Zn@ZnO materials were produced using pulsed laser ablation in an aqueous medium without the use of any reducing agents or surfactants. The detailed structural, morphological, elemental composition, and electrochemical voltammetric analyses revealed a significant improvement in Zn@ZnO performance for selective hydroquinone detection. A broad linear calibration response was obtained as 10-90 μM with high sensitivity of 0.5673 μA μM^-1 cm^-2 and the low detection limit was 0.10443 μM for detection of hydroquinone. The modified Zn@ZnO electrode's excellent electrochemical sensing performance was attributed to the accessibility of a high electrochemically active surface area (EASA = 0.00345 μF/cm²) and an improved electron transfer rate. Stability and antiinterference tests were also carried out. A 100 fold increase in the concentration of common cations and anions (Na⁺, Mg²⁺, Cl^-, SO₄^2-, and NO₃^-) did not affect the selective determination of HQ. As a result, the fabricated electrochemical sensor has a wide range of potential applications in environmental and biomedical science.

Visible light-driven photocatalytic rapid degradation of organic contaminants engaging manganese dioxide-incorporated iron oxide three dimensional nanoflowers

Water pollution via hazardous organic pollutants poses a high threat to the environment and globally imperils aquatic life and human health. Therefore, the elimination of toxic organic waste from water sources is vital to ensure a healthy green environment. In the current work, we synthesized α-MnO₂-Fe₃O₄ 3D-flower like structure using a two-step hydrothermal method and explored the combination in a visible-light-assisted photocatalytic degrdation of dyes. The attained high specific surface area of 82 m²/g with mesoporous nature of α-MnO₂ and Fe₃O₄ together can generate more active sites after exposure to visible light, leading to remarkable photodegradation performance. Significantly, twofold higher dye (methylene blue, MB (94.8%/120 min; crystal violet, CV (93.7%/120 min)) and drug (LVO 91%/90 min) photodegradations were observed with α-MnO₂-Fe₃O₄ as catalyst than pure α-MnO₂ and Fe₃O₄ at pH 6, respectively. This is attributed to the higher surface area and synergistic effect between Mn and Fe. More than 85% stability was observed with optimized catalysts employing MB and CV dyes, demonstrating the excellent reusability of the α-MnO₂-Fe₃O₄. The underlying mechanism indicates that the formation of reactive oxygen species predominantly plays a role in the photodegradation of dyes under visible light. Consequently, these new insights will shed light on the practical applications of the α-MnO₂-Fe₃O₄ 3D-flower-like spherical structure for eco-friendly remediation via wastewater treatment.

Environmental decomposition and remodeled phytotoxicity of framework-based nanomaterials

Zeolitic imidazole frameworks (ZIFs) have attracted a considerable amount of attention for use in environmental applications (e.g., pollutant adsorption and photocatalysis in water treatments). The environmental stability and toxicity of ZIFs are key prerequisites for their practical applications, but information about these factors is largely lacking. The present work finds that pristine ZIFs (ZIF-8 and ZIF-67) photodegrade from frame structures into two-dimensional nanosheets and are oxidized to zinc carbonate (ZIF-8) and Co₃O₄ (ZIF-67) under visible-light irradiation. The photoinduced electrons, holes and free radicals promote dissolution of the metal cores and organic ligands, leading to collapse of the frame structure. The photodegradation of ZIF-8 alleviates developmental inhibition, oxidative stress, plasmolysis, and photosynthetic toxicity, while the photodegradation of ZIF-67 aggravates nanotoxicity. The integration of metabolomics and transcriptomics analysis reveals that unsaturated fatty acid biosynthesis and metal ion-binding transcription contribute to the altered toxicity of ZIF photodegradation. These findings highlight the roles of photodegradation in structural transformation and alteration of the toxicity of ZIFs, alarming the study of pristine metal-organic frameworks (MOFs).

Structure, morphology and modelling studies of polyvinylalcohol nanocomposites reinforced with nickel oxide nanoparticles and graphene quantum dots

Nickel oxide (NiO) nanoparticles (NPs) and graphene quantum dots (GQDs) reinforced polyvinyl alcohol (PVA) nanocomposite films were prepared using a solution casting technique. The physicochemical characteristics of PVA/NiO/GQDs (PNG) nanocomposite films were studied using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). The obtained PNG nanocomposite films showed good mechanical flexibility and improved tensile strength. The influence of nanofiller concentrations on PNG nanocomposite film. The obtained results demonstrate an increase in the activation energy (Ea) up to PNG3 upon increasing the GQDs concentration and thereafter, its decreases. The fundamental interactions of the constituents of PNG nanocomposite film were investigated using density functional theory (DFT). This study on electronic structure reveals that the PVA model indirectly interacts with GQDs through the NiO model. This configuration is favoured in terms of interaction energy (-78 kJ/mol) compared to the one in which PVA interacts directly with the GQDs model.

Ternary Zn1-xNixSe nanostructures as efficient photocatalysts for detoxification of hazardous Congo red, methyl orange, and chrome yellow dyes in wastewater sources

Water contamination by hazardous organic pollutants poses an extreme threat to the environment and globally endangers aquatic life and human health. Hence, the removal of toxic organic effluents from water sources is necessary to ensure a healthy green environment. To this end, a new class of emerging, visible-light-driven Zn- and Ni-based ternary metal-selenide (Zn_1-xNi_xSe) nanophotocatalysts, with tunable nanostructures via regulation of the stoichiometric ratios of Zn and Ni, were synthesized for efficient water purification by a facile one-pot hydrothermal process. These catalysts exhibit outstanding porous properties, with large surface areas and average particle sizes of around 80 ± 10 nm. The as-prepared ternary Zn_1-xNi_xSe catalysts enable improved optical properties, intrinsic conductivity, bandgap reductions, and large numbers of active sites compared with pristine materials, thereby exhibiting outstanding degradation properties against various dye molecules, including Congo red, methyl orange, and chrome-IV upon visible light irradiation. The improved photodegradation capabilities of the Zn_1-xNi_xSe catalysts may be attributed to the synergistic combinations of Zn and Ni selenides, which in turn minimize the recombination rates of the photogenerated carriers compared to their individual constituents. These findings clearly demonstrate that the proposed ternary Zn_1-xNi_xSe catalysts could be potentially used to remove toxic organic contaminants from industrial wastewater.