Biosynthesis of NiO nanoparticles using Senna occidentalis leaves extract: Effects of annealing temperature and antibacterial activity

Abstract

In this work a cost effective and ecofriendly green method for the preparation of NiO nanostructures employing Senna occidentalis (S. occidentalis) leaves extract has been reported. XRD studies show that the 400 °C and 500 °C annealed nanostructures were authenticated as pure face centered cubic phase with an average crystallite size are about 27 nm and 15 nm, respectively. The SEM results show that both the annealed samples were nearly spherical with grain sizes ranging between 65 and 74 nm. The band gap of 400 °C and 500 °C annealed NiO nanoparticles (NPs) was estimated to be 5.28 eV and 5.40 eV, respectively from UV–visible studies while the occurrence of Ni-O stretching in the FTIR spectra validates the formation of NiO. Further this work witnesses that the NiO NPs synthesized from the green route offer better antibacterial activity. The observed maximum zone of inhibition of 500 °C annealed NiO NPs was found to be 20 mm and 19 mm for Serratia marcescens and Bacillus cereus strains and indicates that this material can serve as a prospective drug for biomedical application.