Effect of copper dopant on microstructural and optical properties of NiTiO3 ilmenite materials synthesized by citrate method

In this work, the Ni1-xCuxTiO3 (0 ≤x ≤ 0.1) ilmenite materials were successfully synthesized using the citrate-gel method using nickel nitrate, copper nitrate and titanium (IV) isopropoxide as Ni, Cu, Ti sources and citric acid as complexing reagent. The evolution of the microstructural properties was investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Powder X-ray diffraction pattern confirms the formation of the ilmenite phase for all the samples. The particle size of the prepared samples substantially increased with increase of copper dopant content. The study of phonon vibration by Raman spectroscopy identified a change in structure of NiTiO3 due to Cu dopant. The optical properties with the Cu content was carried out using UV-vis absorption spectroscopy. The reduction of optical band gap from 2.31 eV to 1.99 eV was obtained for undoped NiTiO3 and 10 mol.% Cu dopant in NiTiO3, respectively. To evaluate the photocatalyst properties of NiTiO3, the photocatalytic degradation of congo red under visible light irradiation was carried out. Our results revealed that the copper dopant into NiTiO3 lattice promoted the increase of particle size, decrease of optical bandgap and enhancement of textile photodegradation.