高等学校化学学报 ›› 2025, Vol. 46 ›› Issue (9): 20250076.doi: 10.7503/cjcu20250076

• 物理化学 • 上一篇    下一篇

尖晶石氧化物在电催化氧还原反应中的实际活性位点

倪宇隆, 李静()   

  1. 重庆大学化学化工学院,重庆 401331
  • 收稿日期:2025-03-17 出版日期:2025-09-10 发布日期:2025-05-20
  • 通讯作者: 李静 E-mail:lijing@cqu.edu.cn
  • 基金资助:
    国家自然科学基金(22279012)

Actual Active Sites in Spinel Oxides for Electrocatalytic Oxygen Reduction Reaction

NI Yulong, LI Jing()   

  1. School of Chemistry and Chemical Engineering,Chongqing University,Chongqing 401331,China
  • Received:2025-03-17 Online:2025-09-10 Published:2025-05-20
  • Contact: LI Jing E-mail:lijing@cqu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(22279012)

摘要:

以尖晶石型Co3O4为基体材料, 通过Zn2+和Al3+的选择性掺杂调控其活性位点的分布, 制备了仅保留单一Co3+(八面体位点)或Co2+(四面体位点)的ZnCo2O4和CoAl2O4模型催化剂. 通过X射线衍射(XRD)、 X射线光电子能谱(XPS)和拉曼光谱(Raman)等表征手段证实了掺杂离子对晶体结构的精确调控, 其中, Zn2+选择性占据四面体位点, 而Al3+优先取代八面体位点的Co3+, 从而分别实现了对Co3+和Co2+活性位点的单独研究. 在碱性介质氧还原反应(ORR)测试中, 半电池测试结果表明, 不同活性位点表现出显著的电催化性能差异. Co3O4展现出最优异的ORR活性, 而ZnCo2O4(仅含Co3+位点)的催化性能明显优于CoAl2O4(仅含Co2+位点), Co3O4的半波电位比ZnCo2O4高出50 mV, 而ZnCo2O4的半波电位比CoAl2O4高出120 mV, 表明八面体配位的Co3+在ORR过程中起主导作用. 原位傅里叶变换红外光谱分析结果表明, ZnCo2O4表面在反应过程中检测到明显的*O2-*O2中间物种吸附信号, 而CoAl2O4仅表现出微弱的含氧物种吸附峰, 证实Co3+位点对关键氧中间体的吸附能力显著强于Co2+位点.

关键词: 锌空电池, 氧还原反应, 非贵金属催化剂, 尖晶石氧化物, 电化学原位红外光谱

Abstract:

In this study, ZnCo2O4 and CoAl2O4 model catalysts retaining only a single Co3+(octahedral site) or Co2+(tetrahedral site) were prepared using spinel-type Co3O4 as the base material, and the distribution of their active sites was modulated by selective doping with Zn2+ and Al3+. The precise modulation of the crystal structure by dopant ions, in which Zn2+ selectively occupies the tetrahedral sites and Al3+ preferentially replaces Co3+ in the octahedral sites, has been confirmed by XRD, XPS and Raman spectroscopy, which enables the isolated study of Co2+ and Co3+ active sites, respectively. In the alkaline-mediated oxygen reduction reaction(ORR) test, the half-cell test results show that the different active sites exhibit significant differences in electrocatalytic performance. Co3O4 exhibits the optimal ORR activity, whereas the catalytic performance of ZnCo2O4(Co3+ sites only) is significantly better than that of CoAl2O4(Co2+ sites only), and the half-wave potential of Co3O4 is 50 mV higher than that of ZnCo2O4, while the half-wave potential of ZnCo2O4 is 120 mV higher than that of CoAl2O4, indicating that the octahedrally coordinated Co3+ plays a dominant role in the ORR process. In situ Fourier transform infrared spectroscopy analysis further revealed that obvious *O2- and *O2 intermediate species adsorption signals are detected on the surface of ZnCo2O4 during the reaction process, whereas CoAl2O4 exhibits only weak oxygen-containing species adsorption peaks, confirming that the adsorption capacity of the key oxygen intermediates at the Co3+ site is significantly stronger than that at the Co2+ site.

Key words: Zinc-air battery, Oxygen reduction reaction, Non-precious metal catalyst, Spinel oxide, In situ electrochemical infrared spectroscopy

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