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Water recycling is a convenient way to get around the water shortage and wastewater analysis. The water can be reused for domestic purposes by eliminating organic pollutants through a photocatalytic process. For this aim, the sol-gel dip coating process synthesized ZrO2 nanostructured thin films with tunable structural, morphological, and optical properties and photocatalytic activities. Zr sources (acetate, nitrate, and chloride), annealing temperature (TA), and thickness (d)-dependent structural, morphological, optical, and photocatalytic performances of the ZrO2 films were scrutinized by x-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersive x-ray spectroscopy (EDS), mapping technique, and UV–Vis spectroscopy. The XRD, SEM, EDS, and mapping analyses confirmed the formation of nanostructured ZrO2 thin film. The results revealed that ZrO2 film had a tetragonal phase with various crystallite sizes and different surface morphologies as the Zr sources, TA, and d varied. There were significant variations in the optical absorbance, band gap, refractive index, and absorption coefficient based on Zr sources, TA, and d. Among all ZrO2 films, the film sample synthesized by the Zr-acetate source annealed at TA of 500 °C and with d of 940 nm was found to be the most effective film in terms of optical and crystalline quality as well as photocatalytic performance (94% efficiency in 150 min) for the degradation of methylene blue dye. The enhanced light utilization capability suppressed charge recombination, surface morphology, grain size, defect concentration, and optical band gap values of the nanostructured zirconia thin films are the key factors corresponding to enhanced photocatalytic performance. Highlights: Tunable funtionalities of sol-gel derived ZrO2 nanostructures by Zr sources. The Zr sources leads to variant ZrO2 grain morphologies. A relatively higher crystalline/optical quality owing to using Zr-acetate. The optimum annealing temperature (TA) is 500 °C and the film thickness (d) is 940 nm. Amongest all, the highest photocatalytic performance in zirconia film derived by Zr-acetate source. [ABSTRACT FROM AUTHOR]

The influences of La3+ substituent levels (x = 0–15 at. %) on the structural, surface, optical, photoluminescence, and optical constants of the Zn1-xLaxS (ZLS) thin films, synthesized by sol-gel dip-coating technique were investigated. The derived films have a predominant cubic structure with principally favored crystal plane direction of (111) and hexagonal phase. The crystalline quality and directional orientation of the ZLS thin films varied with the La3+substitution level. The surface anatomy of the films was dense and homogeneous and the average facet roughness was enhanced by increasing the La3+substitution level. UV-Vis explorations clarified that the La3+substitution resulted in a decrement in the band gap energy of the ZLS samples except for certain La3+substitution levels. The photoluminescence spectra exhibited that all samples emitted four chief emissions due to the near band and their variant crystal defects. The obtained optical constants showed strong dependence on the La3+substitution level and the highest values of them were detected for the 10 % La3+ substitution level. Among the produced film samples, the ZnS film sample with 10% La3+ substitution exhibited the best film crystallization and optical quality. Thus, it shows promise as a relatively suitable material for optoelectronic, solar cell, and photocatalytic applications, given its tunable characteristics. Highlights: The first detailed research on the sol-gel derived Zn1-xLaxS (x = 0–15 at. %) thin films. Improved crystalline quality of the ZnS films for the 10 at. % La compared with pure ZnS. Amongst all, the least roughness for the 1 at. % La substitution level. Amongst all, the highest luminescence intensity for the 1 at. % La substitution level. Comparatively, the higher optical constants for the 10 at. % La than those of other substitution levels. [ABSTRACT FROM AUTHOR]