Forming high entropy oxide provides a feasible approach to finding a balance among moderate 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 (LaTMO). However, due to the compositional complexity, clarifying the relevance among the high entropy components, occupancy, TM-O properties, and ORR performance still remains a challenge. Herein, adopting the B site entropy-driven strategy, a series of LaTMO (TM = Cr, Mn, Fe, Co, Ni) with tunable occupancy and TM-O bond properties are synthesized, and the correlations between high entropy elements, 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(CrMnFeCoNi)O delivers a low overpotential of 493 mV (vs. 503 mV for LaMnO) and a minuscule decline by only 1.7% (vs. 4.4% for LaMnO) in half wave potential after 10,000 cycles, which can be associated with the tailored occupancy (1.06) and the significant enhancement in both TM-O covalency (4%) and lattice energy (691.75 kJ mol). This work not only demonstrates the prospects of high entropy LaTMO 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.

中文翻译：

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高熵 La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 具有针对氧还原反应定制的占有率和过渡金属-氧键特性

形成高熵氧化物提供了一种在适度占有率、高过渡金属氧（TM-O）共价和晶格能之间找到平衡的可行方法，这对于确保钙钛矿镧系元素的高效和持久的氧还原反应（ORR）过程至关重要-过渡金属氧化物（LaTMO）。然而，由于成分的复杂性，阐明高熵成分、占有率、TM-O 性质和 ORR 性能之间的相关性仍然是一个挑战。本文采用B位熵驱动策略，合成了一系列具有可调占有率和TM-O键性质的LaTMO（TM=Cr、Mn、Fe、Co、Ni），并分析了高熵元素、占有率、基于晶体场理论和 Phillips-Van Vechten-Levine (P-V-L) 价键理论定量揭示了 TM-O 性质和 ORR 性能。高熵 La(CrMnFeCoNi)O 具有 493 mV 的低过电势（LaMnO 为 503 mV），并且在 10,000 次循环后半波电势仅微弱下降 1.7%（相对于 LaMnO 为 4.4%），这可以与具有定制的占有率 (1.06) 以及 TM-O 共价 (4%) 和晶格能 (691.75 kJ mol) 的显着增强。该工作不仅展示了高熵LaTMO在ORR领域的前景，而且为高熵氧化物ORR催化剂构效关系的定量分析提供了新的视角。