Schiff base complex sol–gel method for LaCoO3 perovskite preparation with high-adsorbed oxygen

A novel Schiff base complex sol–gel method has been used to prepare LaCoO3 producing high ratios of adsorbed (or surface) oxygen (α) to lattice oxygen (β). The as-prepared gels, characterized by Fourier transform infrared spectroscopy (FTIR), showed that both lanthanum and cobalt ions were complexed before calcinations. IR spectra revealed that CO32− and NO3− presented on the sample surfaces during heat treatment. High-resolution transmission electron microscopic (HRTEM) images of all samples showed resolved lattice fringes with the inter-planar spacing 0.37–0.39 nm of the (0 1 2) plane in hexagonal perovskite. BET surface areas of LaCoO3 nano-crystals were 11.7–18.6 m2/g. Ratios of adsorbed (or surface) oxygen (α) to lattice oxygen (β) quantified by X-ray photoemission spectroscopy showed that LaCoO3 prepared by the Schiff base complex method produced higher ratios when bases had higher nitrogen content in molecules. Carbonate and nitrate which were resulting from the oxidation of functional groups in the Schiff base complex, can produce gaseous compounds and leave vacant sites for oxygen in the gas phase to adsorb.