Adsorption and photocatalytic characteristics of cobalt ferrite-reduced graphene oxide and cobalt ferrite-carbon nanotube nanocomposites

Abstract

In this research, cobalt ferrite (CF)-reduced graphene oxide (rGO) and CF-carbon nanotube (CNT) nanocomposites were successfully prepared through a facile co-precipitation method at a low temperature. The structure, microstructure, magnetic, optical and photocatalytic properties of the as-prepared nanocomposite samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM), diffuse reflectance spectroscopy (DRS), Photoluminescence (PL) spectrometer and Fourier transform infrared spectroscopy (FTIR). The mean particle size and saturation magnetization were decreased by the addition of rGO and CNT to the CF. The band gap of the CF decreased from 1.55 to 1.50 and 1.45 eV in presence of rGO and CNT, respectively. The recombination rate of photo-induced electron-hole pairs was further decreased by CNT compared to the rGO. A detailed study on the mechanism and kinetics of dark adsorption and photocatalytic degradation of methylene blue (MB) aqueous solutions by different samples was done. The degradation results were fitted with a high degree of correlation to the Langmuir-Hinshelwood (L-H) model and those for adsorption to the Langmuir model. CF-CNT nanocomposite showed the highest dark adsorption capacity and MB degradation efficiency in all MB concentrations. For the degradation of 10 mg/L methylene blue (MB) solution under visible light, the photocatalytic efficiency of CF-CNT nanocomposite reached 97% within 180 min of reaction time, which was 1.8 times higher than that of CF-rGO nanocomposite and up to 2.5 times than that for pure CF nanoparticles. The remarkable visible light photocatalytic performance CF-CNT nanocomposite with a maximum kinetic rate constant was mainly attributed to the structural, morphological and optical properties. According to the reusability test, only a slight decrease of 4% was observed after the third cycle.