Biosynthesis and photocatalytic properties of SnO2 nanoparticles prepared using aqueous extract of cauliflower

Abstract

This work reports the biosynthesis of Sn(OH)2 using aqueous extract of fresh cauliflower (Brassica oleracea L. var. botrytis), and the subsequent preparation of SnO2 nanoparticles at two different annealing temperatures of 300 and 450 °C for 2 h. The obtained SnO2 nanoparticles were denoted as S1 and S2 for the samples prepared at 300 and 450 °C, respectively. XRD analysis identified rutile tetragonal phase of SnO2 nanoparticles and TEM results gave a quasispherical and spherical morphologies for S1 and S2 respectively of the size range 3.62–6.34 nm. The optical properties were studied with UV–vis and photoluminescence (PL) spectroscopies, and the nanoparticles showed blue shift in their absorption edges. The observed emission peak in the PL spectra found around 419 nm is attributable to oxygen vacancies and defects. Photocatalytic activities of the nanoparticles (S1 and S2) were studied using methylene blue (MB) under ultraviolet light irradiation and the results reveal 91.89 and 88.23% degradation efficiency of MB by S1 and S2 respectively over a period of 180 min.