ZnO/CuSe composite-mediated bandgap modulation for enhanced photocatalytic performance against methyl blue dye

Study of Photodegradation of Bentazon Herbicide by Using ZnO-Sm2O3 Nanocomposite Under UV Light

The removal of organic pollutants from water is significantly important as they have harmful effects on the ecosystem. Heterogeneous photocatalysis is a potential technique for the removal of organic pollutants from the wastewater. In this article, zinc oxide (ZnO) and samarium oxide (Sm2O3) nanoparticles and ZnO-Sm2O3 nanocomposite (ZS) were synthesized by the co-precipitation method. We report the bandgap engineering of zinc oxide (ZnO) by making a composite with samarium oxide (Sm2O3) to enhance the photocatalytic activity. The smaller optical energy bandgap of the ZS nanocomposite as compared to the individual oxide nanoparticles shows that it has a light absorption range from UV to natural light. The photodegradation of bentazon herbicide as a model pollutant has been investigated by using the prepared samples. The photocatalytic activity of the prepared sample against bentazon herbicide was carried out under UV light for 140 min. The degradation efficiency against bentazon of the prepared samples was ZS > ZnO > Sm2O3, respectively. The ZnO-Sm2O3 nanocomposite showed a higher photocatalytic performance against bentazon and achieved a 90% degradation efficiency under a UV light source in 140 min. The pseudo-first-order degradation kinetic was studied under different operational conditions, such as catalyst loading, initial pH and bentazon concentration, showing that the degradation rate of bentazon was strongly influenced by these operational parameters. The obtained optimization conditions for practical application were a catalyst loading of 20 mg, pH of solution equal to 7 and bentazon concentration of 5 ppm for ZS nanocomposite in 60 mL of contaminated water. Furthermore, based on the scavenger study, hydroxyl and superoxide radicals play major role in the degradation experiment. The obtained results show that ZS nanocomposite can be a good potential candidate for wastewater treatment.

Efficient Degradation of Methylene Blue in Industrial Wastewater and High Cycling Stability of Nano ZnO

Photocatalytic degradation research has attracted significant attention in the wake of the increasingly severe global challenge of water pollution. In this study, nano-ZnO was synthesized through a straightforward method using zinc acetate anhydrous as the precursor. The experimental results revealed that annealing conditions significantly influenced the bandgap energy (Eg) of ZnO, with a positive correlation observed between the intensity of photoluminescence (PL) spectra and photocatalytic activity. Under optimal annealing conditions at 300 °C for 1.5 h, the photocatalytic degradation efficiency of methylene blue (MB) exceeded 98% within 40 min of ultraviolet (UV) irradiation, surpassing the efficiencies reported for ZnO in recent studies. This high performance underscores the excellent photocatalytic activity of the synthesized ZnO samples. Furthermore, after five photocatalytic cycles, the degradation efficiency of MB remained above 90%, and the crystalline structure of the ZnO samples remained stable, demonstrating their exceptional structural stability during the photocatalytic process. Additionally, this study examined the effects of stirring conditions and different light sources on MB degradation, providing valuable insights for future research in related fields.

Exploring secondary optical transitions: a study utilizing the DITM method, and enhanced photocatalytic properties in Ni-doped CuSe

This study explores the simultaneous presence of two metal ions of Nickel (Ni) and Copper (Cu) on the formation of a metal selenide (Ni-doped CuSe) in an alkaline environment. The impact of Ni ions on creating the second optical transitions is investigated. Different concentrations amounts of Ni ions (0.01, 0.02, and 0.03 mol) are utilized to produce Ni-doped CuSe semiconductor thin films through a chemical solution deposition method with deposition times varying from 3 to 6 h. Absorbance spectra are employed to determine the band-gap, while Field Emission Scanning Electron Microscopy is utilized for morphological analysis. Structural and elemental analyses are conducted using X-ray Diffraction and Energy Dispersive X-ray Spectroscopy techniques. Additionally, a relatively innovative approach for determining the optical transitions, termed the Derivation Ineffective Thickness Method (DITM), is employed. DITM eliminates the need for thin film thickness and assumptions about the type of transition (direct or indirect) for band-gap calculation. Moreover, a comparison is made between the band-gap obtained from the Tauc model and the transitions obtained by DITM method. Furthermore, it is demonstrated that the optical transitions exhibit two distinct band-gaps associated with nickel selenide (NiSe) as second transition and copper selenide (CuSe) as fundamental transition. The presence of Ni is also found to enhance crystal quality. The study also briefly explores the improved photocatalytic properties of CuSe in the presence of Ni.