ZnO/La2O3/NiO based ternary heterostructure nano-photocatalyst: Preparation, characterization and its application for the degradation of methylene blue

Abstract

ZnO based ternary heterostructure ZnO/(X wt%)La2O3/NiO (X = 1%, 3% and 5% of La2O3) nanoparticles were successfully synthesized employing waste curd as fuel by facile one-pot combustion procedure. The composition, morphology and structure of the fabricated heterostructures were characterized using various microscopic and spectroscopic instruments including using XRD, FTIR, UV–Visible, EDX, FESEM and HRTEM analysis. To evaluate the photo-catalytic degradation efficacy of the prepared ternary nanocomposite, textile dye methylene blue (MB) was selected as benchmark reaction under solar irradiation. The influence of several catalytic variables including light source, catalyst loading, photocatalyst dose, MB concentration, irradiation time, and pH value on the photo-degradation performance was systematically examined and the results were discussed. The results reveal that 3 wt% La2O3 doped ternary ZnO/NiO photocatalyst exhibits excellent performance towards the photocatalytic degradation of the studied dye. The ternary heterostructure i.e. ZnO/(3 wt%) La2O3/NiO exhibits superior MB degradation efficacy of 98% at 150 min under natural solar irradiation. The obtained observations conclude that the prepared nanocomposite exhibits pH dependent photo-catalytic efficacy, and for better results, concentrations of dye and photocatalysts have to be kept in a specific range. Moreover, different light sources have also been applied and their results are compared.

Keywords

• ZnO/La2O3/NiO
• Heterostructure
• Sunlight
• Photocatalyst
• Methylene blue
• Dye degradation