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In the present investigation, ZnO nanoflakes was prepared via sonochemical synthesis route. Effect of ultrasonic treatment time was studied based on structural, morphological and optical properties. X-ray diffraction (XRD) reveals the formation of wurtzite hexagonal crystalline structure of ZnO nanoflakes. Ultrasonic treatments affected the crystallite size and the density of dislocation, which is due to increased nucleation and growth rates of nanoflakes. The samples synthesized at 40–50 min ultrasonic treatment showed a strong absorption band at 605 and 650 (cm−1) versus other treatments, which is an indication of 2D nanostructure (nanoflakes). FE-SEM analysis further confirms the formation of 2D nanostructures of the ZnO. The composition and purity was confirmed by the energy dispersive X-ray (EDX) analysis, which displays the occurrence of Zn and O elements in the sample. Photocatalytic activity (PCA) of ZnO nanoflakes was studied for methyl orange (MO) dye degradation under UV light exposure and up to 93.13 % dye degradation is achieved within 90 min. Effect of various parameters (dye concentration, mass of photocatalytic material) and kinetic study was also performed. Results revealed that the ultrasonic treatment affected the optical and photocatalytic properties of the of ZnO nanoflakes, which could be employed for the remediation of dyes in textile effluents.

A series of Sr1-xZnxFe1-yNiyO19 with composition of x = 0.0, 0.15, 0.30, 0.45, 0.60 and y = 0.0, 0.2, 0.3, 0.4, 0.5 were prepared using micro-emulsion approach and characteristics were studied by XRD, FTIR and UV–vis techniques. The effect of doping was investigated based on the optical, dielectric, structural and photocatalytic properties of Sr1-xZnxFe1-yNiyO19. XRD analyses confirmed the hexagonal crystal structure of pure and doped SrFe12O19 NPs. The lattice parameters, X-ray density, porosity, bulk density and crystallite size of Sr1-xZnxFe1-yNiyO19 and SrFe12O19 were compared. The FTIR analysis confirmed that there was shifting of peaks from region of lower to higher frequency in Sr1-xZnxFe1-yNiyO19, due to the reduction of the size of grains after doping. The current–voltage I-V data shows that there is gradual increase in the conductivity of as prepared doped-material, but the reverse was the case for resistivity, which exhibit good conducting behavior of the fabricated material. Evaluation of the dielectric properties of the samples shows that the AC conductivity and dielectric constant enhanced, while tangent, dielectric loss and resistivity decreased with concentration of the dopants (Zn and Ni). These excellent properties of doped material can be used for the fabrication of various electronic, electrical, microwave and high frequency devices applications. The photocatalytic activity of Sr1-xZnxFe1-yNiyO19 and SrFe12O19 was tested against methyl green (MG) dye. Results revealed that Sr1-xZnxFe1-yNiyO19 degraded 72.23 % of MG dye in 60 min under the exposure of solar light. The recyclability and usability tests revealed that there was a minute loss after successive four runs. Sr1-xZnxFe1-yNiyO19 might have potential applications as a photo-catalyst under solar light irradiation.