Exceptional lattice-oxygen participation on artificially controllable electrochemistry-induced crystalline-amorphous phase to boost oxygen-evolving performance

The development of crystalline-amorphous phase for oxygen-evolving reaction (OER) in water splitting is lagging, and the underlying catalysis mechanism is still unknown. Here, we can facilely construct electrochemistry-induced crystalline-amorphous phase in hybrid La_0.33SrCo_0.5Fe_0.5O_x (H-LSCF) nanofibers based on the behavior of high-valence cubic perovskites and Ruddlesden-Popper perovskites after the OER, where such unique combination can be artificially modulated. This nano-sized combination surpasses its pure-phase counterparts and exhibits ultra-low overpotentials of 260 mV and 240 mV at 10 mA cm⁻² in 0.1 M and 1 M KOH, respectively, which can be ascribed to their favorable solid-liquid contact, higher Co valence and stronger Co-O covalency to accelerate OER electron transport. The beneficial changes in various surface properties of H-LSCF ensure its stability for 80 h and 60 h in 0.1 M and 1 M KOH, respectively. In-situ ¹⁸O isotope-labelled experiments directly reveal that such combination can trigger exceptional lattice-oxygen activation mechanism.