Synthesis and microstructure of La_1−xCa_xCoO₃ nanoparticles and their catalytic activity for CO oxidation

Perovskite nanoparticles of La_1−xCa_xCoO₃ (x = 0, 0.2, 0.3, 0.5) were synthesized by the combustion method using polyvinyl alcohol (PVA) and corresponding metal nitrates. Microstructure of samples was characterized by high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) combined with x-ray diffraction (XRD). The nanoparticles were characterized by thermogravimetric and differential thermal analysis (TG-DTA) and BET (Brunauer–Emmet–Teller). A high surface area (15–21 m² g⁻¹) at low temperature (600 °C) of samples was obtained. The optimal preparative conditions were PVA/metals 2:1 by mole, pH = 3 and 80 °C for gel formation. Perovskites exhibit a good catalytic activity in total oxidation of CO at the low temperature (<250 °C) of reaction. (paper)