Photocatalytic zinc oxide nanoparticles synthesis using Peltophorum pterocarpum leaf extract and their characterization

Abstract

For the first time, zinc oxide nanoparticles (ZnONPs) were synthesized using the aqueous extract of Peltophorum pterocarpum leaves by the reduction of zinc acetate. The phenolic compounds present in the leaf extract reduced zinc acetate to ZnONPs. The synthesis process was visually monitored and a strong absorption peak observed at 365 nm in UV–vis spectrum confirmed the formation of ZnONPs. The band gap energy was estimated as 3.39 eV. FE-SEM image revealed discrete flower-shaped ZnONPs and characteristic peaks for zinc and oxygen were observed in EDS spectrum. Hexagonal wurtzite structure was confirmed in XRD spectrum and the crystallite size was calculated as 11.64 nm. In addition, the lattice parameter values were consistent with the standard values for ZnONPs. BET analysis affirmed the mesoporous structure (pore diameter = 10.77 nm) with a relatively high surface area (13.56 m2/g). The thermal stability of the ZnONPs was evidenced from a TGA curve in which only 12% weight loss was observed. The specific functional groups responsible for reduction and capping of ZnONPs were denoted in FTIR spectrum. A sharp band at 425 cm–1 indicated the zinc-oxygen stretching. The photocatalytic potential of ZnONPs was evidenced by the degradation of methylene blue (MB) dye under sunlight irradiation. It was possible to degrade 95% of the dye within 120 min. Therefore, the synthesized ZnONPs can be used as photocatalysts for the degradation of dyes from wastewater.