Research has been focused on regulating the amorphous surface of Ir-based materials to achieve a higher oxygen evolution reaction (OER) activity. The IrO x amorphous layer is generally considered to be substantial enough to break the limitation created by the conventional adsorbate evolution mechanism (AEM) in acidic media. In this work, we used lanthanides to regulate IrO x amorphization−crystallization through inhibiting the crystallization of iridium atoms in the calcination process. The chosen route created abundant crystalline−amorphous (c-a) interfaces, which greatly enhanced the charge transfer kinetics and the stability of the materials. The mass activity of iridium in the synthesized IrO 2 @LuIr 1−n O x (OH) y structure reached 128.3 A/g Ir , which is 14.6-fold that of the benchmark IrO 2 . All the IrO 2 @LnIr 1−n O x (OH) y (Ln = La−Lu) structures reflected 290−300 mV of overpotential at 10 mA/cm geo 2 . We demonstrate that a highly active c-a interface possesses an efficient charge transfer capability and is conducive to the stability of the activated oxygen species. The surface-activated oxygen species and the tensile strain [IrO 6 ] octahedron regulated by lanthanides are synergistically beneficial for increasing the intrinsic OER activity. Our research findings introduce c-a interface generation by the regulation of lanthanides as a new method for the rational design of robust OER catalysts.

The surface reconstruction of iridium-based derivatives (A x Ir y O z ) was extensively demonstrated to have an excellent oxygen evolution reaction (OER) performance in an acidic medium. It is urgent to use various spectroscopy and computational methods to explore the electronic state changes in the surface reconstruction process. Herein, the underestimated Lu 2 Ir 2 O 7 was synthesized and investigated. Four typical forms of electrochemistry impedance spectra involved in the reconstruction process revealed three dominating forms of reconstructed pyrochlore in the OER stage, including the inner intact pyrochlore, mid metastable [IrO 6 ]−[IrO 6 ] framework, and the outer collapse amorphous layer. The enhancing electron transport efficiency of the corner-shared [IrO 6 ]−[IrO 6 ] framework was revealed as a critical role in acidic systems. The density of state (DOS) for the constructed [IrO 6 ]− [IrO 6 ] framework corroborated the enhancement of Ir−O hybridization and the downshift of the d-band center. Additionally, we contrast the pristine and reconstruction properties of the Pr 2 Ir 2 O 7 , Eu 2 Ir 2 O 7 , and Lu 2 Ir 2 O 7 in alkaline and acidic media. The DOS and the XANES results reveal the scale relationship between the O 2p band center and the intrinsic activity for bulk pyrochlore in alkaline media. The highest O 2p center and the highest Ir−O hybridization of Lu 2 Ir 2 O 7 exhibited the best OER performance among the Ir-based pyrochlore, up to a ninefold improvement in Ir-mass activity compared to IrO 2 . Our findings emphasize the electrochemical behavior of the reconstruction process for activated water-splitting performance.

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