Promoting directional reconstruction of double perovskites for efficient water splitting

Abstract

Double perovskite oxides are promising electrocatalysts for water electrolysis due to their tunable structure and ordered ion arrangement. However, while in-situ surface reconstruction of perovskites enhances oxygen evolution reaction (OER) activity, this process is inherently uncontrollable, as structural instability drives irreversible phase transitions and active metal dissolution, ultimately degrading both activity and stability. Herein, we developed an Fe³⁺-induced directional reconstruction strategy that transforms double perovskite Sr₂NiMoO₆ into a heterostructure consisting of crystalline SrMoO₄ and amorphous NiFeO_xH_y. In-situ analyses reveal that this structural reconstruction simultaneously optimizes OH⁻ adsorption at NiFe dual-active sites and activates more lattice oxygen contributions to the reaction. Moreover, dynamically dissolved Mo species during the OER serve as electronic modulators to facilitate rapid reconfiguration of Ni ions while suppressing detrimental over-oxidation and dissolution. This strategy can be extended to optimize other double/triple perovskite oxides, where directional reconstruction and enhanced OER activity/stability are obtained.