Chinese Journal of Catalysis ›› 2025, Vol. 72: 164-175.DOI: 10.1016/S1872-2067(24)60276-7

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Active non-bonding oxygen mediate lattice oxygen oxidation on NiFe2O4 achieving efficient and stable water oxidation

Jiangyu Tanga, Xiao Wangb, Yunfa Wanga, Min Shia, Peng Huoa, Jianxiang Wua, Qiaoxia Lia,*(), Qunjie Xua,c,*()   

  1. aShanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai Engineering Research Center of Energy-Saving in Heat Exchange Systems, Shanghai University of Electric Power, Shanghai 200090, China
    bSchool of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China
    cShanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
  • Received:2024-12-06 Accepted:2025-02-03 Online:2025-05-18 Published:2025-05-20
  • Contact: *E-mail: liqiaoxia@shiep.edu.cn (Q. Li), xuqunjie@shiep.edu.cn (Q. Xu).
  • Supported by:
    National Natural Science Foundation of China(22172098);Science and Technology Commission of Shanghai Municipality(23ZR1424900);Science and Technology Commission of Shanghai Municipality(22010501200);Science and Technology Commission of Shanghai Municipality(21ZR1425000);Science and Technology Commission of Shanghai Municipality(19DZ2271100)

Abstract:

The oxygen evolution reaction (OER) serves as a fundamental half-reaction in the electrolysis of water for hydrogen production, which is restricted by the sluggish OER reaction kinetics and unable to be practically applied. The traditional lattice oxygen oxidation mechanism (LOM) offers an advantageous route by circumventing the formation of M-OOH* in the adsorption evolution mechanism (AEM), thus enhancing the reaction kinetics of the OER but resulting in possible structural destabilization due to the decreased M-O bond order. Fortunately, the asymmetry of tetrahedral and octahedral sites in transition metal spinel oxides permits the existence of non-bonding oxygen, which could be activated by rational band structure design for direct O-O coupling, where the M-O bond maintains its initial bond order. Here, non-bonding oxygen was introduced into NiFe2O4 via annealing in an oxygen-deficient atmosphere. Then, in-situ grown sulfate species on octahedral nickel sites significantly improved the reactivity of the non-bonding oxygen electrons, thereby facilitating the transformation of the redox center from metal to oxygen. LOM based on non-bonding oxygen (LOMNB) was successfully activated within NiFe2O4, exhibiting a low overpotential of 206 mV to achieve a current density of 10 mA cm-2 and excellent durability of stable operation for over 150 h. Additionally, catalysts featuring varying band structures were synthesized for comparative analysis, and it was found that the reversible redox processes of non-bonding oxygen and the accumulation of non-bonding oxygen species containing 2p holes are critical prerequisites for triggering and sustaining the LOMNB pathway in transition metal spinel oxides. These findings may provide valuable insights for the future development of spinel-oxide-based LOM catalysts.

Key words: Non-bonding oxygen, Lattice oxygen oxidation mechanism, Oxygen evolution reaction, NiFe2O4, Spinel oxide