Facile chemical fabrication of Ni doped CoAl2O4 nano-spinel photocatalysts: Physico-chemical properties and photodegradation of toxic malachite green dye under visible light

Abstract

ABSTRACT In this present study, we report the facile chemical fabrication of Ni-doped CoAl2O4 (NCA) (Co1-xNixAl2O4-δ, where x = 0.0, 0.05, 0.10, 0.15 and 0.20) nano-spinel photocatalyst materials by a simple chemical precipitation route. The XRD data revealed the presence of cubic crystal structure for CoAl2O4 and Ni-doped CoAl2O4 samples. Presence of vibration modes of M − O, Al−O, and M − O− Al in the spinel lattice structure in the materials was found out by FTIR analysis. The particle size analysis and SEM confirmed the presence of nanosized grains in the samples. The occurrence of appropriate amount of Co, Al, O and Ni was detected by EDAX analysis. The optical characteristics of Co1-xNixAl2O4-δ were studied using UV spectral studies. The band gap energy (Eg) of NCA was found to be in the range of 2.14 to 2.32 eV. The photocatalytic activity studies confirmed that the fabricated NCA nanoparticles have good photocatalytic behaviour in the degradation of malachite green (MG) dye solution under visible light irradiation. Further, the obtained results revealed that the doping of Ni has influenced the structural, spectral, morphology and the photocatalytic properties of the CoAl2O4 spinel materials to a greater extent. In addition, the factors affecting the photo-degradation of MG including composition of photocatalyst, photocatalyst loading, pH of the dye solution and the irradiation time were investigated and reported. The studies indicate that the 15% Ni-doped CoAl2O4 is a promising candidate material among all for the photocatalytic degradation of highly toxic dyes such as MG.