Phytogenic fabrication of CeO₂@SnO₂ heterojunction nanostructures for antioxidant studies

Abstract

CeO2@SnO2 heterojunction nanostructures (HNs) have been synthesized via a green and phytogenic method using aqueous leaf extract of Tradescantia spathacea. The structural, optical and surface morphological studies were investigated using Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–Vis diffuse reflectance spectrophotometer (UV–Vis DRS), Photoluminescence (PL), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET). Powder XRD data revealed tetragonal rutile structure of SnO2 as well as the formation of cubic fluorite CeO2 in which the crystallite size was in the range of 10 to 24 nm. The functional groups of phytochemicals on the surface of HNs were confirmed by FTIR. UV–Vis DRS showed a red-shift toward visible light which showed a reduced band gap energy. This reduction in band gap was also confirmed by valence band-XPS (VB-XPS). BET study showed lower surface area to volume ratio which was supported by SEM results through surface modification. Photoantioxidant activities of SnO2 and CeO2@SnO2 HNs were tested, and it was found enhanced in the presence of light in comparison to dark condition. This suggests that CeO2@SnO2 HNs could be a potential candidate for biological related applications. Graphical Abstract: [Figure not available: see fulltext.]