Abstract: The Co₃O₄/C catalyst with nanoparticles was synthesized by a liquid control precipitation method. X-ray diffraction and transmission electron microscopy were used to characterize the structure and morphology of the catalyst. The electrocatalytic activity of the catalyst was investigated by line-scan voltammetry and cyclic voltammetry using rotating disk electrode technique. The results indicated that the Co₃O₄/C has electrocatalytic activity for the oxygen reduction reaction (ORR). The exchange current density of Co₃O₄/C catalyst obtained by the Koutecky-Levich theory is 1.1 x10^-9 A/cm². The overall electron transfer number for the ORR was determined to be ~2, suggesting that the ORR catalyzed by Co₃O₄/C is a 2- electron transfer pathway. The process of oxygen adsorption on the surface of Co₃O₄/C was simulated through Materials Studio to explore the catalytic mechanism. The state density, electron density, bond length, and adsorption energy of O and Co were calculated. Restricted by the geometric configuration, O₂ can only be adsorbed by the Pauling adsorption mode. After adsorption, the O 2p orbit and Co 3d orbit hybridize with each other and form a new chemical bond. The π bond of O₂ is mainly weakened by the electron transfer from Co to O. At the same time, the other O atom is activated. H⁺ can easily bond with the other O and the catalytic reaction occurs through 2- electron transfer pathway.

Key words: liquid control precipitation method, oxygen reduction reaction, electrocatalysis, reaction mechanism, adsorption mode;carbon, cobaltosic oxide