Spinel oxides are considered as promising low-cost non-precious metal electrocatalysts for oxygen evolution reaction (OER) due to their desirable catalytic activities and fast kinetics. However, as a result of the structural complexity of spinel oxides, systematic and in-depth studies on enhancing the OER performance of spinel oxides remain inadequate. In particular, the construction of active sites regarding the large number of unoccupied octahedral interstices has not yet been explored. Herein, more octahedral sites with high OER activities are constructed on the surface of spinel oxides via a cationic misalignment, which is induced by the defects in the spinel oxide solutions, i.e., MoFe₂O₄ and CoFe₂O₄ nanosheets supported on an iron foam (MCFO NS/IF). With increased active sites and modified electronic structure, the state-of-the-art electrocatalyst exhibits the excellent OER catalytic activity with an onset potential of 1.41 V versus RHE and an overpotential of 290 mV to achieve a current density of 500 mA cm⁻². Moreover, such an electrocatalyst also demonstrates fast kinetics with the Tafel slope of 38 mV dec⁻¹ and superior durability by maintaining the OER activity at 250 mA cm⁻² for 1000 h.

中文翻译：

---

从尖晶石氧化物固溶体中的原子尺度几何工程构建活性位点，实现高效、稳健的析氧反应电催化剂

尖晶石氧化物由于其理想的催化活性和快速的动力学而被认为是用于析氧反应（OER）的有前途的低成本非贵金属电催化剂。然而，由于尖晶石氧化物结构的复杂性，对于提高尖晶石氧化物OER性能的系统和深入研究仍然不足。特别是，尚未探索关于大量未占据的八面体间隙的活性位点的构建。在此，通过阳离子错位在尖晶石氧化物表面构建了更多具有高OER活性的八面体位点，这是由尖晶石氧化物溶液中的缺陷引起的，即负载在铁上的MoFe ₂ O ₄和CoFe ₂ O ₄纳米片泡沫（MCFO NS/IF）。通过增加活性位点和改进的电子结构，最先进的电催化剂表现出优异的OER催化活性，相对于RHE，起始电势为1.41 V，过电势为290 mV，可实现500 mA cm -2 的电流^密度。此外，这种电催化剂还表现出塔菲尔斜率为38 mV dec ^{-1的快速动力学，以及通过在250 mA cm -2}下保持OER活性1000小时而表现出优异的耐久性。