Preparation, characterisation and photocatalytic activity of La-doped ZnO nanopowders synthesised using auto-combustion

Abstract

Nanocrystalline nanoparticles of pristine ZnO and La-doped ZnO have been synthesised using a combustion method using various concentrations of lanthanum dopant followed by calcination for 3 h at 700 °C. The crystalline structure, chemical composition and optical characteristics have been characterised using X-ray diffraction (XRD), scanning electron spectroscopy (SEM) attached with energy dispersive X-ray (EDX) spectroscopy, Brunauer Emmett Teller (BET), UV-vis. spectroscopy and photoluminescence (PL) spectroscopy. Absorption spectra showed that the absorbance increased with La-doping and the blue shift observed was due to an increase in the band gap from 3.24 to 3.27 eV. The photocatalytic activities of the samples prepared were evaluated using the photocatalytic degradation of methyl orange (MO) under irradiation by sunlight. The textile mill effluents containing organic matter were also irradiated with sunlight inducing photocatalysis and the chemical oxygen demand (COD) of the treated effluent were investigated. The results showed that the ZnO photocatalyst doped with 1.0 at.% lanthanum exhibited four times enhancement in the photocatalytic activity compared to pure ZnO.