Successful synthesis of LaFeO3 nanoporous powders with high catalytic and photocatalytic performances: Investigation of precursor effect

Abstract

Porous LaFeO3 powders with high catalytic and photocatalytic activities were successfully synthesized by sol-gel method using nitrate and chloride precursors. The precursor effect on the crystal structure, morphology, specific surface area and optical properties of the prepared powders was fully determined. Thermogravimetric and X-ray diffraction analyzes showed the formation of the orthorhombic perovskite phase (Pnma, #62) at annealing temperature of 800 and 1000 °C for powder prepared by nitride and chloride salts, respectively. The scanning electron microscopy images revealed a significant effect of precursor type on nanoparticles morphology. It was found that powder prepared from chloride salts is more porous than that prepared with nitrate salts. The estimated surface area of LaFeO3 nanoparticles ranges between 5.94 and 11.56 m2/g and the band gap varies from 2.19 to 2.27 eV. Methylene blue (MB) dye was used to investigate the catalytic and photocatalytic properties of LaFeO3 powders. Both prepared powder types showed good catalytic activity and high photocatalytic performance under visible irradiation in removing MB dye. The adsorption kinetics data of MB molecules on LaFeO3 nanoparticles are well fitted to the pseudo-first order model. Powder synthesized with chloride salts demonstrated high photodegradation efficiency of MB dye compared to that prepared by nitrate salts, which can be attributed to its relatively small band gap and high porosity. These two factors ensure a greater number of photogenerated electrons and more sites for photocatalytic reactions.