Synthesis and characterization of mixed oxides : experimental and theoretical study of their photocatalytic activity

Abstract

In this study, LaFeO3 powders with crucial catalytic and photocatalytic performance were successfully prepared through the sol-gel method using chloride and nitrate salts. The influence of the used precursor on the crystallinity, morphology, specific surface area, and optical properties was investigated. TGA and XRD patterns confirmed the formation of the LaFeO3 orthorhombic perovskite phase (Pnma, #62). SEM images highlighted a significant effect of the precursor type on the surface morphology of the synthesized nanoparticles. The obtained band gap varies between 2.19 - 2.27 eV. The kinetic and isotherm adsorption studies revealed that the adsorption of MB molecules on LaFeO3 nanoparticles fitted well with the pseudo-second-order and Freundlich models. Moreover, the thermodynamic study demonstrated that the adsorption of MB on the LaFeO3 samples is spontaneous, exothermic, and more favorable at low temperatures while the magnitude of enthalpy changes energies suggested a physisorption. Hence, LaFeO3 samples prepared with chloride salts are expected to show high photodegradation efficiency of MB dye. In addition, our study was completed by the theoretical investigation, using DFT within GGA+U, of the Bulk and surface properties of LaFeO3. A perfect agreement is found between the experimental results and the theoretical ones.