Photo-degradation of a mixture of dyes using Barium doped ZnO nanoparticles

Abstract

The potential use of Barium (Ba) doped ZnO nanoparticles for the photo-degradation of a mixture of dyes that mimics natural effluents has been attempted. Undoped and Ba-doped ZnO nanoparticles were efficiently synthesized via co-precipitation method. The effect of Ba concentration on the structural, morphological, optical properties and photocatalytic activity of ZnO nanoparticles was probed. X-ray diffraction analysis disclosed the formation of hexagonal polycrystalline nanoparticles with ZnO wurtzite crystal structure having an average crystallite sizes ranging from 20 nm for pure ZnO up to 28 nm in diameter after adding different ratios of barium. The FE-SEM images revealed rod-like nanoflakes morphology for all of the samples with a clear influence of the presence of Ba impurities on the width of the rods. Mapping analysis showed even Ba distribution in the ZnO lattice. FTIR spectra manifested the presence of the characteristic absorption peak at 400–600 cm−1 of Zn–O stretching modes confirming the target nanoparticles synthesis. While the BET and BJH data analysis indicated increased specific surface area and reduced pore volume as a result of Ba intercalation. The incorporation of Ba into the ZnO matrix has shifted the 371 nm absorption band to 475 nm as observed in photoluminescence spectra for all samples. This red shift in the absorption was reflected in lowering the band energy enabling it to decolorize a dyes mixture under visible light illumination. Based on the aforesaid results, the Ba doping is responsible for the visible light driven photocatalytic activity of the composites.