Ruddlesden–Popper (R-P) perovskite oxides have attracted much attention as highly active and stable bifunctional materials for the oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) in alkaline solutions due to the nonuse of precious metal elements. Herein, a triple (H⁺, O^2–, and electron) conductive R-P perovskite oxide, La_1.2Sr_0.8Ni_0.6Fe_0.4O_4+δ, was prepared, and the valence state of transition metal cations and highly oxidized oxygen (O^–/O₂^2–) in the structure was tuned by a low-temperature fluorine substitution treatment. The homogeneous distribution of the fluorine elements across the particles of the R-P perovskite oxide after its fluorination was confirmed by high-resolution transmission electron microscopy (HRTEM) images. By regulation of the amount of highly oxidative state oxygen species and the valence state of transition metal cations in the R-P perovskite structure, the material exhibits a significant enhancement for both the OER and ORR electrocatalytic activities. The fluoridated La_1.2Sr_0.8Ni_0.6Fe_0.4O_4+δF_y (LSNF-OF) achieves a low OER overpotential of 308.1 mV in a 1 M KOH electrolyte at a current density of 10 mA cm^–2. This is superior to both commercial Co₃O₄ and the pristine sample without fluorination. The LSNF-OF electrode in an aqueous Zn-air battery (ZAB) exhibits a peak power density of 19.15 W g^–1 at a current density of 24 mA g^–1. The low-temperature trace fluorination can enhance the electrocatalytic efficiency of perovskite oxides. This technique can be applied to various types of metal oxides.

中文翻译：

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低温氟化对RP钙钛矿La1.2Sr0.8Ni0.6Fe0.4O4+δ本征电催化活性的调控

由于不使用贵金属元素，Ruddlesden-Popper（RP）钙钛矿氧化物作为在碱性溶液中进行析氧反应（OER）/氧还原反应（ORR）的高活性和稳定的双功能材料而备受关注。在此，制备了三重（H ⁺、O ^2–和电子）导电RP钙钛矿氧化物La _1.2 Sr _0.8 Ni _0.6 Fe _0.4 O _4+δ，过渡金属阳离子和高度氧化的氧（O）的价态通过低温氟取代处理调整了结构中的^- /O ₂ ^2- )。高分辨率透射电子显微镜 (HRTEM) 图像证实了氟化后氟元素在 RP 钙钛矿氧化物颗粒上的均匀分布。通过调节RP钙钛矿结构中高氧化态氧的数量和过渡金属阳离子的价态，该材料表现出OER和ORR电催化活性的显着增强。氟化La _1.2 Sr _0.8 Ni _0.6 Fe _0.4 O _4+δ F _y (LSNF-OF) 在1 M KOH 电解质中、电流密度为10 mA cm ^–2时实现了308.1 mV 的低OER 过电势。这优于商业 Co ₃ O ₄和未经氟化的原始样品。水性锌空气电池 (ZAB) 中的 LSNF-OF 电极在电流密度为 24 mA g ^{–1时表现出 19.15 W g –1}的峰值功率密度。低温微量氟化可以提高钙钛矿氧化物的电催化效率。该技术可应用于各种类型的金属氧化物。