催化学报

催化学报 ›› 2011, Vol. 32 ›› Issue (4): 624-629.DOI: 10.3724/SP.J.1088.2011.01012

• 研究论文 • 上一篇    下一篇

Co3O4/C 催化氧还原反应的活性及机理

李赏, 朱广文, 邱鹏, 荣刚, 潘牧   

  1. 武汉理工大学材料复合新技术国家重点实验室, 湖北武汉 430070
  • 收稿日期:2010-10-19 修回日期:2010-01-17 出版日期:2011-04-18 发布日期:2014-08-30

Electrocatalytic Activity of Co3O4/C for Oxygen Reduction and the Reaction Mechanism

LI Shang*, ZHU Guangwen, QIU Peng, RONG Gang, PAN Mu   

  1. State Key Laboratory of Advanced Technology for Materials Synthesis and Progressing, Wuhan University of Technology, Wuhan 430070, Hubei, China
  • Received:2010-10-19 Revised:2010-01-17 Online:2011-04-18 Published:2014-08-30

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摘要： 采用液相控制沉淀法制备了平均粒径约为 10 nm 的 Co3O4/C 催化剂, 运用 X 射线衍射和透射电镜对催化剂进行了表征, 通过循环伏安法和线性扫描伏安法测试了催化剂催化氧还原反应的性能. 结果表明, 在酸性条件下, Co3O4/C 对氧还原反应具有电催化活性. 利用 Koutecky-Levich 理论计算得到了交换电流密度为 1.1x10-9  A/cm2, 电子转移数为 2.0569, 表明氧还原过程是两电子还原过程. 利用 Materials Studio 分子模拟软件对 Co3O4 表面上氧吸附过程进行了模拟, 计算得到了 O 和 Co 原子吸附前后的态密度、电子密度、键长和吸附能. 结果表明, 几何构型的限制使得 O 在 Co 活性点上只能发生端基吸附, 吸附后 O 2p 轨道和 Co 3d 轨道重叠杂化, 生成新的化学键. 这主要是通过 Co 原子周围的电子向 O 原子周围富集来弱化 O2 中的 π 键, 并活化未吸附端 O 原子, H+ 易从另一侧与未吸附端 O 原子形成新的化学键, 发生二电子反应.

关键词: 液相控制沉淀法, 氧还原反应, 电催化, 反应机理, 吸附模式, 碳, 四氧化三钴

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