Photocatalytic performance of Ni1-xCuxFe2O4 nanoparticles: studies on structure, microstructure, electrical and optical properties and dye photodegradation

Abstract

Abstract Water pollution is a major global problem. Among its pollutants, dyes stand out, which are overused in a variety of industries and cannot be easily removed by conventional waste treatment methods. Ni 1-x Cu x Fe 2 O 4 nanoparticles (NPs), x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0, were synthesized by auto-combustion flash method for application as photocatalyst in the degradation of methylene blue (MB) dye. The synthesized NPs were characterized using different experimental techniques and their photocatalytic performance was investigated. The microstructure of the prepared Ni–-Cu ferrite nanoparticles was also explored using positron annihilation spectroscopy (PAS). The nanocrystalline structure with the main spinel and tetragonal phases for low and high Cu content samples, respectively, with the size ranging from 14.7 to 40.4 nm for the prepared ferrite samples was confirmed by the results of X-ray diffraction (XRD), Fourier transform infrared (FTIR) and transmission electron microscope (TEM) measurements. The UV–Vis absorption spectra of the synthesized ferrite nanoparticles reveal that the optical indirect band gap values of these samples ranged from 4.86 to 4.90 eV. The electrical measurement results found that the dielectric constant and electrical conductivity values of Ni–Cu ferrite sample x = 0.2 are the highest compared to other samples. Also, the microstructure of the Ni 0.8 Cu 0.2 Fe 2 O 4 sample showed the lowest average defect density compared to other samples and the defect structure of all prepared samples are similar. Results of photocatalytic measurements at pH 12.45 or addition of H 2 O 2 showed almost complete degradation (~ 97%) after 30 min of solar light irradiation. Correlation between photocatalytic activity and microstructure parameters as well as some measured parameters of other techniques used found that the microstructure has the most effective influence on the photocatalytic performance of the studied ferrite samples. Graphical abstract