The effects of B-site substitution (B═Mn, Fe, and Co) in La-based perovskite oxides (LPOs); LaMnO₃, LaFeO₃, LaCoO₃, as bifunctional electrocatalysts during oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in metal–air batteries (MABs) under an alkaline electrolyte (pH = 13) are investigated using density functional theory (DFT). It is found that LaMnO₃ exhibits higher ORR activity than others with ORR overpotential (η_ORR) of 0.57 V, but its OER activity is poor with OER overpotential (η_OER) of 1.12 V. The η_ORR (0.59 V) and η_OER (1.13 V) of LaMn_0.75Fe_0.25O₃ closely resemble those of LaMnO₃, suggesting that Fe substitution does not yield appreciable enhancements in activity. Fe substitution reduces the ORR and OER activity because the adsorption energies of intermediate species on Fe-substituted LPOs surfaces are too strong to obtain a potential determining step for ORR and OER. According to Sabatier's principle, the LaMn_0.25Co_0.75O₃ demonstrates superior OER activity compared to the other composition, while ORR activity approximates that of LaMnO₃, evidenced by η_ORR of 0.65 V and η_OER of 0.53 V. The Co-terminated LaMn_0.25Co_0.75O₃ shows bifunctional activity higher than Mn/Co termination, indicating that Co is an active site for OER and Mn is a promoter for improved ORR activity.

中文翻译：

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B位取代（B=Mn、Fe和Co）对La基钙钛矿氧化物作为可充电金属-空气电池双功能电催化剂影响的第一性原理研究

La基钙钛矿氧化物（LPO）中B位取代（B=Mn、Fe和Co）的影响；使用密度泛函理论研究了LaMnO ₃、LaFeO ₃、LaCoO ₃作为双功能电催化剂在碱性电解质（pH = 13）下金属空气电池（MAB）中氧还原反应（ORR）和析氧反应（OER）过程中的情况（密度泛函理论）。结果发现，LaMnO ₃表现出比其他材料更高的 ORR 活性，ORR 过电势 ( η _ORR ) 为 0.57 V，但其 OER 活性较差，OER 过电势 ( η _OER ) 为 1.12 V。η _ORR (0.59 V) 和η _OER LaMn _0.75 Fe _0.25 O _{3的(1.13 V)与LaMnO 3}的(1.13 V)非常相似，这表明Fe替代不会产生活性的明显增强。 Fe 取代降低了 ORR 和 OER 活性，因为 Fe 取代的 LPO 表面上的中间物质的吸附能太强，无法获得 ORR 和 OER 的潜在决定步骤。根据 Sabatier 原理，与其他组合物相比， LaMn _0.25 Co _0.75 O _{3表现出优异的 OER 活性，而 ORR 活性接近 LaMnO 3}，由0.65 V 的η _ORR和0.53 V 的η _{OER证明。 0.25} Co _0.75 O ₃显示出高于Mn/Co终止的双功能活性，表明Co是OER的活性位点，Mn是改善ORR活性的促进剂。