Chem. J. Chinese Universities ›› 2025, Vol. 46 ›› Issue (9): 20250076.doi: 10.7503/cjcu20250076

• Physical Chemistry • Previous Articles     Next Articles

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)

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

CLC Number: 

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