Effect of Co²⁺ and Ni²⁺ co-doping on SnO₂ synthesized via phytogenic method for photoantioxidant studies and photoconversion of 4-nitrophenol

Abstract

Tin dioxide (SnO2) and cobalt and nickel co-doped-SnO2 (Co,Ni)-SnO2 nanoparticles (NPs) have been synthesized via phytogenic and green method using an aqueous leaf extract of Tradescantia spathacea. The structural, optical and surface morphological studies were analyzed using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectrophotometer (UV–vis DRS), Photoluminescence spectroscopy (PL), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and BET. Powder XRD data revealed tetragonal rutile structure of SnO2 in which the crystallite size was in the range of 13–22 nm. The attachment of organic compounds on the surface of NPs was confirmed by FTIR. UV–vis DRS showed the red-shift to visible light in which the reduction of band gap was confirmed by Valence band X-ray photoelectron spectroscopy (VB-XPS). The PL intensity was reduced indicating the successful incorporation of Co and Ni dopants into SnO2 lattice. The photoantioxidant activities of the SnO2 and (Co,Ni)-SnO2 NPs were enhanced under visible light. Similarly, the photocatalytic conversion of 4-nitrophenol to 4-nitrophenolate ions was also enhanced under the visible light irradiation.