J. Mater. Sci. Technol. ›› 2024, Vol. 194: 236-246.DOI: 10.1016/j.jmst.2023.12.077

• Research Article • Previous Articles     Next Articles

High entropy La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 with tailored eg occupancy and transition metal-oxygen bond properties for oxygen reduction reaction

Wenyi Lia, Zhenxin Zhaoa, Jinyu Zhaoa, Yongzhen Wanga,b, Xiaomin Wanga,*   

  1. aCollege of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
    bShanxi Joint Laboratory of Coal based Solid Waste Resource Utilization and Green Ecological Development, Taiyuan 030024, China
  • Received:2023-09-13 Revised:2023-11-26 Accepted:2023-12-01 Published:2024-09-20 Online:2024-03-06
  • Contact: *E-mail address: wangxiaomin@tyut.edu.cn (X. Wang).

Abstract: Forming high entropy oxide provides a feasible approach to finding a balance among moderate eg occupancy, high transition metal-oxygen (TM-O) covalency, and lattice energy, which is essential to ensure efficient and durable oxygen reduction reaction (ORR) process for perovskite lanthanide-transition metal oxides (LaTMO3). However, due to the compositional complexity, clarifying the relevance among the high entropy components, eg occupancy, TM-O properties, and ORR performance still remains a challenge. Herein, adopting the B site entropy-driven strategy, a series of LaTMO3 (TM = Cr, Mn, Fe, Co, Ni) with tunable eg occupancy and TM-O bond properties are synthesized, and the correlations between high entropy elements, eg occupancy, TM-O properties, and ORR performances are revealed quantitively based on the crystal field theory and the Phillips-Van Vechten-Levine (P-V-L) valence bond theory. High entropy La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 delivers a low overpotential of 493 mV (vs. 503 mV for LaMnO3) and a minuscule decline by only 1.7% (vs. 4.4% for LaMnO3) in half wave potential after 10,000 cycles, which can be associated with the tailored eg occupancy (1.06) and the significant enhancement in both TM-O covalency (4%) and lattice energy (691.75 kJ mol-1). This work not only demonstrates the prospects of high entropy LaTMO3 in the ORR field but also provides a new perspective for the quantitative analysis of the structure-activity relationship for high entropy oxide ORR catalysts.

Key words: High entropy oxide, eg occupancy, TM-O covalency, TM-O lattice energy, LaTMO3, Oxygen reduction reaction