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A significant amount of pollutants containing organics, toxic elements, and heavy metals are discharged daily from the textile and pharmaceutical industries into clean water leading to various diseases worldwide. In the present work, sunlight-mediated yttrium (Y)-praseodymium (Pr) co-doped ZnO photocatalysts anchored on reduced graphene (rGO) and conducting polymer (PANI) were synthesized via co-precipitation and ultrasonication approach for the photodegradation of synthetic dyes. The as-synthesized catalysts were characterized through XRD, FTIR, Raman, FE-SEM, UV–Vis, and PL for structural, morphological, and optical studies. The XRD diffraction peaks have confirmed the successful doping of Y and Pr without altering the basic hexagonal structure of ZnO and anchoring of rGO and PANI. FTIR demonstrated the Zn–O bond vibration, and Raman exhibited the peaks related to optical phonon modes of ZnO in all grown samples with a small shift. Roughly spherical particles anchored on PANI and rGO were confirmed by FE-SEM images. The optical energy bandgap has shifted towards the visible region for grown samples, evident from UV–Visible spectra. PL spectra exhibited lower recombination of charge carriers in rGO and PANI-based catalysts. The photocatalytic degradation experiment against methylene blue (MB) and methyl orange (MO) dyes under solar light demonstrated that rGO anchored catalyst completely degraded both dyes under 40 min solar light irradiation with an observed rate constant 0.1403 min−1, and 0.1402 min−1, respectively, and has higher reusability up to 6th cycle towards MB dye. The enhanced photodegradation efficiency is because of lower recombination of charge carriers in rGO-based composites than others, electron acceptor nature, fast electron mobility, massive surface area, and higher generation of reactive species such as superoxide and hydroxyl radicals (confirmed by scavengers tests). Moreover, the results exhibit the importance of grown catalysts for potential application in wastewater treatment. [ABSTRACT FROM AUTHOR]

The structural, magnetic, and dielectric properties of Yb ions substituted Ca-hexaferrites (Ca-HFs) synthesized using the citrate sol–gel method were studied. XRD and SEM, techniques were used to evaluate the size and shape of the samples. X-ray powder diffraction (XRD) patterns of prepared samples revealed the production of a single M-type single phase hexagonal ferrite with space group 167: R-3c, hexagonal of P63/mmc for structural characterization. Using a scanning electron microscope, the surface morphology of the particle was investigated, and the particle size was determined (SEM). FTIR spectra confirmed the iron–oxygen bands of X-type hexagonal ferrites at tetrahedral and octahedral sites. The high influence of Yb+3 substitutions on the FTIR spectra further confirmed that the dopants play a significant role in these ferrites. The electrical and dielectric properties of Yb substituted Ca-HFs were investigated using the complex impedance spectroscopy technique at various temperatures, frequencies, and substitution ratios. Yb substitution was discovered to have a significant impact on dielectric loss, dielectric constant, Ac conductivity, and dissipation factor. It was fascinating to see how Ytterbium replacement resulted in a significant improvement in magnetic characteristics. With a given substitution ratio, activation energy levels can be altered to a certain level. The Verway Hopping Model, Maxwell Wagner Model, and Koop's theory were used to describe the conduction and polarization mechanisms. The trend was also influenced by the substitution of Yb. Eddy current losses, devices like Multi-Layer Chip Inductors (MLCI), and other microwave applications can benefit from the achieved ranges of both features. [ABSTRACT FROM AUTHOR]

Nano-composites consisting of polyvinyl alcohol (PVA) immersed with Sr0.7Cr0.3Fe12O19 hexaferrites nanoparticles were successfully synthesized by two-step process. Nanoparticles (Sr0.7Cr0.3Fe12O19) were prepared by the sol–gel auto-combustion method and then embedded with polyvinyl alcohol matrix by the ultrasound in situ emulsion technique. The result indicates that the fabricated nanoparticles were homogeneously diffused in the matrix of PVA. Characterization of the synthesized material was done by the X-ray diffraction, Raman spectra and EDX analysis. The peaks of the XRD pattern become more intense with increasing the ferrite content in the polymer matrix which suggests that the crystallinity was improved with the addition of the ferrite content in the polymer matrix. Crystallite size and cell volume lie in the range of 34–59 nm and 688.83–693.82 nm, respectively. The magnetic field-dependent magnetic properties of the synthesized samples were inspected at room temperature by the vibrating sample magnetometry (VSM). The linearity of Ms, Hc, Mr values and shape of the hysteresis loop clearly indicate that the prepared ferrites nanoparticles were dispersed evenly within the polymer matrix. With the addition of ferrites in polymer composites, saturation magnetization, remanence, and coercivity were found to be enhanced. Saturation magnetization and remanent magnetization ranges from 6–42 emu/g and 4–22 emu/g, respectively, and magnetocrystalline anisotropy ranges from 3.7–5.6 (105 erg/cm3). At low frequency, dielectric constant and dielectric loss are high with few relaxation peaks. Both the real and imaginary parts of permittivity demonstrate increasing trend with the addition of ferrite content in the polymer matrix. AC conductivity of the Ferrite–PVA nano-composites was found to be increased with the increase of frequency following the Joncher's law. The increasing behavior of dielectric parameters with increasing ferrite ratio in PVA is suitable for different applications, especially in energy storage devices. [ABSTRACT FROM AUTHOR]

Binary NiO-Fe2O3, NiO-CdO nanocomposites, and ternary NiO-Fe2O3-CdO nanocomposite are synthesized using facile co-precipitation method, and their photocatalytic and antibacterial properties are studied. The as-obtained products are characterized using different analytical techniques. The microstructural parameters were calculated using X-ray diffraction data. UV–vis spectra technique was used to calculate the bandgap and listed 3.1, 2.7, and 2.5 eV for NiO-Fe2O3, NiO-CdO, and NiO-Fe2O3-CdO nanocomposite, respectively. The photocatalytic activity of as-obtained products was tested under visible light against methylene blue (MB) dye. The NiO-Fe2O3-CdO nanocomposite has shown higher degradation efficiency as compared to binary nanocomposites and revealed improve electron–hole separation efficiency. The photocatalytic performance of NiO-Fe2O3-CdO nanocomposite was also tested for other synthetic dyes such as rhodamine-B (RhB), methyl orange (MO), and cresol red (CR). The antibacterial performance of grown products was tested against E. coli bacteria. The ternary NiO-Fe2O3-CdO nanocomposite has shown higher antibacterial activity than binary NiO-Fe2O3 and NiO-CdO nanocomposites. [ABSTRACT FROM AUTHOR]