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In this study, pure ZnO and iron (Fe) and cobalt (Co) co-doped ZnO nanoparticles were synthesized by varying Fe and Co concentrations using the co-precipitation method. The physical properties of as-prepared samples were investigated through XRD, FTIR, SEM, and UV–vis spectroscopy. X-ray diffraction confirmed the strong influence of Fe and Co ions on structural parameters without disturbing the basic ZnO hexagonal structure. The microstructural study was executed by using the Scherrer, W–H, and SSP methods. FTIR confirmed the presence of Zn–O, and Zn–M–O (M = Fe, Co) vibrational modes, which further confirmed the successful incorporation of dopants ions. The energy bandgap (E g) extracted from UV–vis spectra has shown red-shift (3.37–2.7 eV) for decreasing Fe contents, whereas blue-shift (3.37–3.39 eV) for increasing Co concentration. SEM was used to investigate surface morphology, which represents the high rate of agglomeration. The photocatalytic test was performed on grown samples against various dyes and also observed the effects of varying concentrations of Fe and Co ions. The maximum degradation efficiency (98.8%) at 6%Fe and 4%Co under direct sunlight in 60 min against methylene blue (MB) was achieved. The photocatalytic activity of optimized concentration (6%Fe and 4%Co) was further tested against cresol red (CR), methyl orange (MO), safranin-O (SO), rhodamine-B (RhB), and methyl red (MR) dyes. The maximum degradation efficiency against MR dye (96.0%) was observed. The antibacterial test against Staphylococcus aureus and Klebsiella pneumoniae bacterial strains have shown that co-doped ZnO nanoparticles have a higher activity as compared to pristine ZnO, and furthermore, the sample with 6%Fe and 4%Co concentration exposed the highest antibacterial actively for both bacterial strains. [ABSTRACT FROM AUTHOR]

Bi–Cr-substituted Y-type hexa-ferrites were prepared via a micro-emulsion method. Formation of the hexagonal phase was confirmed by X-ray diffraction (XRD) analysis. The size of the crystallites of all the samples was in the range 31.58–37.67 nm and their Fourier transform infrared (FTIR) spectroscopy bands were observed in the range ~ 450–650 cm-1. These bands indicated successful incorporation of Bi–Cr in the Y-type hexagonal ferrites. The existence of metal-oxygen bands at the tetrahedral and octahedral sites confirmed that all the prepared samples exhibit Y-type hexagonal ferrites structures. The magnetic parameters such as saturation magnetization, retentivity and coercivity revealed significant variations with the increase of Bi–Cr contents. Frequency and composition dependent variations in the dielectric constant (ε′), dielectric loss (ε"), tan loss, and other parameters were observed, for example the value of ε′ decreased as the Bi–Cr content increased. These optimised results are highly desirable for the application of these nanosized hard ferrites in various microwave devices [ABSTRACT FROM AUTHOR]

Thin films of ZnO and Co, Ni co-doped ZnO nanorods were successfully synthesized on the silicon substrate (100) by the hydrothermal method. The grown thin films were annealed at 105 °C for 4.5 h and characterized by employing different analytical techniques to investigate the effects of co-doping on structural, morphological, and optical properties of ZnO nanorods. X-ray diffraction (XRD) analysis confirmed the successful substitution of dopants (Co and Ni) without altering the hexagonal wurtzite structure of ZnO. The crystallite size and micro-strain of grown films were calculated by employing Scherer, W–H, and SSP methods. The unit cell volume and lattice parameters were increased for Co doping, moreover by increasing Ni concentration as a co-dopant these parameters were decreased. Crystallite size of ZnO, ZnCo, ZnCoNi3, ZnCoNi6 and ZnCoNi9 grown thin films were 73 nm, 42 nm, 71 nm, 60 nm, and 52 nm respectively. The Fourier transform infrared spectroscopy (FTIR) has shown the existence of characteristic vibrational bonds of Zn–O in all co-doped samples at 499.35 cm−1, 561.25 cm−1, 570.89 cm−1, 565.10 cm−1 , and 553.53 cm−1 , respectively. SEM images show the surface morphology of grown thin films, which indicates that the diameter of nanorods is increased by increasing Ni contents. The UV–visible spectroscopy was employed to measure the energy bandgap (E g) using Tauc's plot. The optical energy band gap was decreased (3.37–3.16) eV for all co-doped samples. The redshift in energy bandgap by Co and Ni co-doping is mainly due to the strong orbital coupling and generation of new energy states between the VB and CB. The other optical parameters including optical absorption coefficient (α) , transmittance (T) , skin depth, optical density (OD) , extinction coefficient (k), refractive index (n), optical conductivity (σ opt), and dielectric constants (ε r , ε i) of the grown thin films were also discussed. • Hydrothermally derived Co, Ni co-doped ZnO nanorods; Structural, optical, and morphological study. • Variation in microstructural parameters calculated by Scherrer, W–H, and SSP methods. • Nanorods are successfully grown on thin film of Si (100) substrate. • The optical parameters i.e. energy band gap, optical absorption coefficient, transmittance, skin depth, etc. were studied. [ABSTRACT FROM AUTHOR]

Novel Zn 0 · 95 Mn 0 · 05 O and Zn 0 · 9 Mn 0.05 M 0.05 O (M = Al, Bi, Sr, Ag) nanocrystals were prepared via the co-precipitation technique. The X-ray diffraction pattern confirmed the substitution of Mn, Al, Bi, Sr, and Ag dopants without altering the basic ZnO structure. The microstructural study was performed by employing the Scherrer plot, Williamson-Hall, and SSP methods. The energy bandgap calculated from UV–vis spectra using different methods observed red-shifted by co-doping. The other optical parameters were also studied and discussed in detail. The FTIR spectra confirmed the presence of Zn–O, and Zn-M–O vibrational modes. Raman spectra demonstrated the presence of ZnO phonon modes, and the Raman shift exhibited the structural defects induced by dopants. The PL spectra showed strong NBE and DLE in the UV and visible region due to extrinsic defects. The IV measurements exhibited the enhancement in the electrical conductivity of ZnO by co-doping. The photocatalytic activity was performed under direct sunlight for methyl orange and methylene blue dyes, and the enhanced degradation efficiency was achieved by co-doping. Furthermore, this article enhances the understanding of tuning the physical properties of ZnO by co-doping and introduces a new class of sunlight-driven photocatalysts. [ABSTRACT FROM AUTHOR]

Novel direct dual Z-scheme ZnO-Er 2 O 3 -Nd 2 O 3 @rGO heterostructured nanocomposite along with simple ZnO-Er 2 O 3 -Nd 2 O 3 nanocomposite was prepared by co-precipitation route. The X-ray diffraction pattern exhibited the diffraction peaks associated with ZnO (hexagonal), Er 2 O 3 (cubic), and Nd 2 O 3 (hexagonal) in both nanocomposites. The FTIR spectra further confirmed the formation of nanocomposites. The energy bandgap of simple and rGO decorated nanocomposites were 3.1 and 2.82 eV. The antibacterial characteristics of grown samples showed that the rGO anchored nanocomposite has higher antibacterial activity as compared to simple nanocomposite. The ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite exhibited higher photodegradation (97.0%) against methylene blue (MB) than simple nanocomposite (86.0%). The effectiveness of grown ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite as photocatalyst was also tested for degradation of other dyes such as RhB, MO, CR, and SO. The effect of operating parameters was investigated for ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite. A possible conventional heterojunction and Z-scheme for the degradation using ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposite has been designed to elucidate the photocatalytic mechanism. • ZnO-Er 2 O 3 -Nd 2 O 3 and ZnO-Er 2 O 3 -Nd 2 O 3 @rGO nanocomposites successfully prepared. • The photocatalytic application was studied using MB, RhB, MO, CR and SO dyes. • The effect of operating parameters for the degradation of SO dye investigated. • The antibacterial activity against different bacterial strains was investigated. [ABSTRACT FROM AUTHOR]