Synthesis of Co3O4 nanoparticles with controllable size and their catalytic properity

Co₃O₄ nanoparticles of controllable size were synthesized via a variant microemulsion method combined with hydrothermal treatment. With this improved method, Co₃O₄ nanoparticles with uniform shape and narrow size distribution were controllably synthesized. By varying the surfactant and water ratio, particles of around 27.97 nm, 42.88 nm and 48.99 nm were synthesized. These nanoparticle catalysts behaved differently at low and high temperature. These samples showed high activity for CO oxidation and 100% CO conversion was achieved at 30 °C. However, the catalysts gradually lost their activity after about 100 min. Our research found that CO₂ had a huge influence on the stability of catalysts at low temperature. The relationship between stability at 30 °C and ratio of Co³⁺/Co²⁺, as well as particle size and desorption rate of CO₂, was also thoroughly investigated in this work.