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

Based on that high-valence cubic perovskite can keep crystalline while Ruddlesden-Popper perovskites tend to become amorphous after oxygen evolution reaction (OER), a unique electrochemistry-include crystalline-amorphous phase on La 0.33 SrCo 0.5 Fe 0.5 O x nanofiber is develpoed as a superior catalyst for OER. La 0.33 SrCo 0.5 Fe 0.5 O x nanofiber triggers an exceptional lattice-oxygen activation mechanism to exhibit a top-level OER performance. • Nano-sized crystalline-amorphous combination triggers lattice-oxygen activation mechanism to boost oxygen-evolving performance. • La 0.33 SrCo 0.5 Fe 0.5 O x - nanofiber delivers ultra-low overpotential of 260 mV and 240 mV to achieve 10 mA cm −2 in 0.1 M KOH and 1 M KOH, respectively. • Unique crystalline-amorphous combination can be artificially modulated by initial doping level and sintering temperature. 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 0.33 SrCo 0.5 Fe 0.5 O 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 18 O isotope-labelled experiments directly reveal that such combination can trigger exceptional lattice-oxygen activation mechanism.