Environmentally benign Azadirachta indica-mediated green approach for the zinc zirconate nanocomposite synthesis: An alternative to the toxic chemical approach

Abstract

Perovskite zinc zirconate nanocomposites were synthesized via two diverse methods (coprecipitation and biosynthesis) to compare their characteristics. The Azadirachta Indica (Neem) leaf extract was utilized in the green-mediated approach. The as-prepared samples were characterized using XRD, UV–Vis absorption, FTIR, and XPS analysis. X-ray diffraction results reveal the presence of ZnO/ZrO2/ZnZrO3 nanocomposites in a single matrix. The green variant unveiled a larger average crystallite size compared to the chemical variant. The UV–vis absorption spectra of the biosynthesized sample show a significant red shift to that of a chemically synthesized sample and hence the biosynthesized variant has a significantly lower optical band gap energy (3.19 eV) than the chemical variant (3.24 eV). FTIR analysis shows a similar pattern for both variants, however, the presence of biomolecules is noticed in the biosynthesized zinc zirconate nanocomposite. The presence of elements and their binding states was comprehended using XPS investigations. The biosynthesized sample demonstrated a clear splitting of the Zr 3d spin–orbit, despite the chemically synthesized sample having a broad peak. The SEM micrographs of synthesized ZnO/ZrO2/ZnZrO3 nanocomposites display the agglomeration of particles. The elemental analysis confirms the existence of zinc (Zn), zirconium (Zr), and oxygen (O). The TG/DTA analysis corroborates the thermal stability of the samples at elevated temperatures. Though both synthesis techniques exhibit comparable traits, the green-mediated ZnZrO3 nanocomposites have greater significance as they pave ways to synthesize ZnO/ZrO2/ZnZrO3 nanocomposites economically, environment-friendly, and by reducing the utility of hazardous chemical reagents.