Synthesis of Ternary Nanocomposites (Srfe12 O19/Tio2/Zno) By Sol-Gel Method for Application of Pollutant Abatement of Organic Dye Degradation Studies

The current study is focused on fabrication of a ternary metal oxide nanocomposite (ZnO/CuO/Ag2O) as an efficient and superior photocatalyst by step-wise implanting of p-type CuO and Ag2O semiconductors onto an n-type semiconductor (ZnO) via a chemical method. The structural and textural characteristics of the manufactured samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy combined with electron dispersive spectroscopy (FESEM-EDS) and UV–visible spectroscopy. The photocatalytic performance of the fabricated ternary nanocomposite was tested against the photocatalytic degradation of crystal violet (CV) and rhodamine B (RhB) organic dyes under solar light irradiation. The ternary nanocomposite demonstrated about 99.05% and 97.38% degradation efficiency toward CV and RhB dyes under solar light irradiation in a time period of 105 min. The calculated rate constants (k, min−1) for degradation under solar light over the ZnO/CuO/Ag2O nanocomposite were 4.26 and 3.61 times higher than the k value obtained over ZnO nanoparticles for CV and RhB dyes, respectively. The main reactive species taking part in the photodegradation processes were •OH and •O2− over ZnO/CuO/Ag2O photocatalysts under solar light illumination. Furthermore, the recycle experiments confirmed good reusability and photo-stability of the ZnO/CuO/Ag2O ternary nanocomposite.

The pure titania (TiO2) and the heterogeneous ternary magnetic nanocomposite of copper ferrite/ferrite oxide (CuFe2O4/Fe2O3) deposited by titanium dioxide (TiO2) were fabricated using a facile one-pot hydrothermal synthesis for the photocatalytic decomposition of methylene blue (MB) dye, under visible light. The nanocomposite was encoded as TCF in this work, where T stands for TiO2, C for CuFe2O4 and F for Fe2O3. Various techniques such as powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy, diffuse reflectance spectroscopy, nitrogen physisorption, and vibrational sample magnetometry (VSM) were used to characterize the prepared samples. The PXRD data showed that the samples had pure anatase structure and the average crystal size of anatase TiO2 in the pure titania and ternary nanocomposite were calculated 147 Å and 135 Å, respectively. The nitrogen physisorption analysis data showed that the pore diameter was increased from 10.6 nm in pure titania to 16.0 nm in TCF. The pore volume was also increased from 0.316 in titania to 0.383 cm3/g in TCF sample. It also increased the typical magnitude of the mesopores’ diameter and volume per weight but it reduced the specific surface area of the samples. The VSM analysis of the ternary nanocomposite showed a considerable magnetic property of the sample (1.99 emu/g), qualifying it as a paramagnetic material. The photocatalytic decomposition efficiency of MB reached 77% and 68% in the presence of pure titania and TCF ternary nanocomposite, after 240-min exposure by the visible light. Active species trapping experiments showed that the major active species responsible for the photodecomposition of MB in the presence of TCF are {text{O}}_{2}^{ cdot - } radicals and holes (h+).

Constructing Mn3O4/Cu hybrid nanorods as superior photocatalyst

To heighten the absorption to visible light and improve photocatalytic degradation to organic pollutants, a novel photocatalyst of m-Bi2O4/Bi2O2CO3 was constructed through a facile hydrothermal method. The crystal structure, optical properties, morphology, composition and photocatalytic ability of the photocatalysts were characterized via X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, field emission scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscope (TEM), high resolution TEM, selected-area electron diffraction and X-ray photoelectron spectroscopy technologies. The as-prepared photocatalysts could efficiently degrade rhodamine B and mixed dye under visible light. The removal rate was up to 95.3% within 50 min. The results demonstrated that m-Bi2O4/Bi2O2CO3 photocatalysts showed outstanding photocatalytic degradation ability compared to the single photocatalyst with the narrow band gap. In addition, photocurrent response tests certified that the heterostructure of the photocatalysts effectively accelerated the separation and migration of photo-induced electrons and holes. Active species trapping experiments indicated that holes (h+) and superoxide radical (•O2−) were major species rather than hydroxyl radicals (•OH) during the degradation process of organics. According to the test results, a probable photocatalytic mechanism was proposed. This work provided a new and efficient photocatalyst for environmental remediation and water treatment.

Synthesis of iron(II,III) oxide/zinc oxide/copper(II) oxide (Fe3O4/ZnO/CuO) nanocomposites and their photosonocatalytic property for organic dye removal

We report the synthesis of TiO 2-supported monometallic Ag , Sn and bimetallic AgSn nanoparticle catalysts prepared using sol–gel method via a rational nanoparticle encapsulation route. The samples were thoroughly characterized by ultraviolet-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) with image mapping and Brunauer–Emmett–Teller (BET) surface area analyzer. The supported bimetallic AgSn catalyst had the anatase structure, surface area of 50 m2/g and 2.6 ± 0.6 nm particle size. The efficiency of the catalysts was evaluated on photodegradation of methylene blue (MB) dye under visible light. The photocatalytic activity of MB was significantly enhanced in the presence of bimetallic AgSn nanoparticles (NPs) as compared to individual metal nanoparticles. Reusability study of the photocatalyst showed that the catalyst can be reused upto 5 runs with minimal loss in activity. Kinetic study revealed that the degradation reaction follows a pseudo first-order pathway.

TiO2/NiFe2-xCexO4/rGO ternary magnetic nanocomposite as separable and recyclable photocatalyst

Facile synthesis of Ni-based layered double hydroxides with superior photocatalytic performance for tetracycline antibiotic degradation

A novel magnetic cadmium titanate–copper ferrite (CdTiO3/CuFe2O4) nanocomposite, in which spherical CuFe2O4 nanoparticles were loaded onto the surface of CdTiO3 nanoplates, was successfully synthesized via a sol–gel hydrothermal route at 180 °C. The structure, morphology, magnetic and optical properties of the as-prepared nanocomposite were respectively characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area analysis, UV-visible diffuse reflectance spectroscopy (DRS), vibrating sample magnetometry (VSM) and photoluminescence (PL) spectroscopy. The photocatalytic activity of this novel CdTiO3-based magnetic nanocomposite was investigated for the degradation of organic dye pollutants such as methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) in the presence of H2O2 under visible light irradiation. The results showed that the photocatalyst completely degraded three dyes within 90–100 min. Compared with pure CdTiO3 and CuFe2O4, the heterogeneous CdTiO3/CuFe2O4 nanocomposite exhibited significantly enhanced photocatalytic efficiency. On the basis of the results of the OH trapping and photoluminescence (PL) experiments, the enhanced photocatalytic performance was mainly ascribed to the efficient separation of photo-induced electron–hole pairs and the formation of highly active hydroxyl radicals (OH) species in the CdTiO3/CuFe2O4 photocatalytic oxidation system. The PL measurements of the CdTiO3/CuFe2O4 nanocomposite also indicated an enhanced separation of photo-induced electron–hole pairs. Moreover, the nanocomposite could be easily separated and recycled from contaminant solution using a magnet without a decrease in their photocatalytic activity due to their good magnetic separation performance and excellent chemical stability. Based on these findings, CdTiO3/CuFe2O4 nanocomposite could be a promising visible-light-driven magnetic photocatalyst for converting solar energy to chemical energy for environmental remediation.

Transition metal sulfide semiconductors have achieved significant attention in the field of photocatalysis and degradation of pollutants. MoS2 with a two dimensional (2D) layered structure, a narrow bandgap and the ability of getting excited while being exposed to visible light, has demonstrated great potential in visible-light-driven photocatalysts. However, it possesses fast-paced recombination of charges. In this study, the coupled MoS2 nanosheets were synthesized with ZnO nanorods to develop the heterojunctions photocatalyst in order to obtain superior photoactivity. The charge transfer in this composite is not adequate to achieve desirable activity. Therefore, heterojunction was modified by reduced graphene oxide (RGO) nanosheets and carbon nanotubes (CNTs) to develop the RGO/ZnO/MoS2 and CNTs/ZnO/MoS2 ternary nanocomposites. The structure, morphology, composition, optical and photocatalytic properties of the as-fabricated samples were characterized through X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray (EDX), elemental mapping, Photoluminescence (PL), Ultraviolet–Visible spectroscopy (UV-VIS), and Brunauer-Emmett-Teller (BET) techniques. The photo-catalytic performance of all samples was evaluated through photodegradation of aniline in aqueous solution. The combination of RGO or CNTs into the ZnO/MoS2 greatly promoted the catalytic activity. However, the resulting RGO/ZnO/MoS2 ternary nanocomposites showed appreciably increased catalytic performance, faster than that of CNTs/ZnO/MoS2. Charge carrier transfer studies, the BET surface area analysis, and the optical studies confirmed this superiority. The role of operational variables namely, solution pH, catalyst dosage amount, and initial concentration of aniline was then investigated for obtaining maximum degradation. Complete degradation was observed, in the case of pH = 4, catalyst dosage of 0.7 g/L and aniline concentration of 80 ppm, and light intensity of 100 W. According to the results of trapping experiments, hydroxyl radical was found to be the main active species in the photocatalytic reaction. Meanwhile, a plausible mechanism was proposed for describing the degradation of aniline upon ternary composite. Moreover, the catalyst showed excellent reusability and stability after five consecutive cycles due to the synergistic effect between its components. Total-Organic-Carbon concentration (TOC) results suggested that complete mineralization of aniline occurred after 210 min of irradiation. Finally, a real petrochemical wastewater sample was evaluated for testing the catalytic ability of the as-fabricated composites in real case studies and it was observed that the process successfully quenched 100% and 93% of Chemical Oxygen Demand (COD) and TOC in the wastewater, respectively.

Nanophotocatalysts are applied for different applications, and their usage has been enhanced remarkably since a decade. On the other hand, cross-coupling reactions of C–N bonds have found increasing popularity for coupling derivatives of organic compounds such as aniline using diverse catalysts. Nanoheterogeneous photocatalysts can offer suitable platforms for the C–N coupling of aniline derivatives. However, the design of a photocatalyst on the nanoscale with remarkable activity and selectivity, made of noble-free elements, is highly welcome. In this study, the half-filled electronic configuration and shallow trapping properties of Fe were employed to reduce the energy band gap of the system. Moreover, the large ionic radius of lanthanide leads to large surface activity. Thus, bi- and trinuclear nano-oxide nanophotocatalysts were synthesized based on the titanium, iron, and lanthanide elements (TixFeyOz, TixFeyLamOz) to obtain logically designed photocatalysts with high selectivity, durability, and operation speed under visible light. In addition, designing photocatalysts in the nanoscale was the ultimate target of this study to use the highest benefit of the nanoscale, which is high surface activity. The developed nanophotocatalysts were used for coupling aniline and its 10 derivatives under visible light. The mechanism of the migration of electrons and the C–N reaction was also investigated in detail. In addition, both obtained nanophotocatalysts were applied in five different solvents and eight different conditions so the best condition for the reaction could be determined. Furthermore, the photocatalytic mechanism was studied in detail. The final nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), inductively coupled plasma mass spectrometry (ICP-MS), Brunauer–Emmett–Teller (BET) surface activity, Barrett–Joyner–Halenda (BJH) method, UV–vis spectroscopy, photoluminescence emission spectra, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), NMR spectra, mass spectra, and CHN elemental analysis. Both nanocomposites exhibited high photocatalytic activities in coupling aniline and its derivatives under visible light. However, the TixFeyLamOz nanophotocatalyst showed a higher activity (90% conversion to obtain 2,4 dinitro-n-phenylaniline) than the TixFeyOz nanophotocatalyst (68% conversion to obtain 2,4 dinitro-n-phenylaniline), which is mainly due to its higher surface activity because of its lanthanide content.

N-heterocyclic carbene-Pd(II) complex based on theophylline supported on Fe3O4@SiO2 nanoparticles: Highly active, durable and magnetically separable catalyst for green Suzuki-Miyaura and Sonogashira-Hagihara coupling reactions

This study reports the synthesis and characterization of an environmentally friendly, cost‐effective, and sustainable Pd‐heterogeneous catalyst anchored on superparamagnetic silica‐coated iron oxide. The synthesized Pd‐SB/MNP nanomagnetic catalyst was extensively characterized using Fourier transform infrared (FTIR), inductively coupled plasma optical emission spectroscopy (ICP‐OES), X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), energy‐dispersive spectrometry (EDS), vibrating sample magnetometry (VSM), field emission scanning electron microscopy (FE‐SEM), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET), and high‐resolution transmission electron microscopy (HR‐TEM). The Pd‐SB/MNP catalyst showed remarkable efficiency in catalyzing the reduction of nitroarene and Cr(VI) under mild reaction conditions using an eco‐friendly solvent. The catalyst exhibits facile recovery through external magnetization, enabling its efficient recycling and reutilization for at least 10 cycles while demonstrating minimal Pd loss, as confirmed by rigorous hot filtration testing and ICP‐OES analysis. These results comply with the industry's prescribed thresholds for permissible levels of residual metallic content. The results suggest that the synthesized Pd‐SB/MNP catalyst holds great potential for various industrial applications.

Facile synthesis of mesoporous black N–TiO2 photocatalyst for efficient charge separation and the visible-driven photocatalytic mechanism of ibuprofen degradation

In this paper, a molecularly imprinted TiO2/WO3-coated magnetic Fe3O4@SiO2 nanocomposite was developed for photocatalytic degradation. Fe3O4 nanoparticles were first prepared by a traditional co-precipitation method, and then a SiO2 shell was grown on the surface of the Fe3O4 nanoparticles. Finally, a 4-nitrophenol imprinted TiO2/WO3 coating was obtained on the surface of the Fe3O4@SiO2 nanocomposite via a sol-gel method and subsequent calcination. The new composite was characterised by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high resolution TEM (HRTEM) and vibrating sample magnetometry (VSM). In addition, the adsorption ability and photocatalytic activity of the composite were investigated. Results showed that the imprinted composite had higher adsorption ability for the template than the non-imprinted composite. The imprinted catalyst could degrade 4-nitrophenol under visible light with a first-order reaction rate of 0.1039 h–1, which was ~2.5 times that of the non-imprinted catalyst. The new imprinted catalyst showed good catalytic selectivity, an ease of being recycled by an external magnetic field, good reusability, no need for additional chemicals, and allows the possibility of utilising solar light as energy resource. Therefore, the catalyst can be potentially applied for ‘green’, low-cost and effective degradation of 4-nitrophenol in real wastewater.