A Doping-Induced SrCo 0.4 Fe 0.6 O 3 /CoFe 2 O 4 Nanocomposite for Efficient Oxygen Evolution in Alkaline Media.

Perovskite and spinel oxides are promising alternatives to noble metal-based electrocatalysts for oxygen evolution reaction (OER). Herein, a novel perovskite/spinel nanocomposite comprised of SrCo 0.4 Fe 0.6 O 3 and CoFe 2 O 4 (SCF/CF) is prepared through a simple one-step method that incorporates iron doping into a SrCoO 3- δ matrix, circumventing complex fabrication processes typical of these materials. At a Fe dopant content of 60%, the CoFe 2 O 4 spinel phase is directly precipitated from the parent SrCo 0.4 Fe 0.6 O 3 perovskite phase and the number of active B-site metals (Co/Fe) in the parent SCF can be maximized. This nanocomposite exhibits a remarkable OER activity in alkaline media with a small overpotentional of 294 mV at 10 mA cm -2 . According to surface states analysis, the parent SCF perovskite remains in its pristine form under alkaline OER conditions, serving as a stable substrate, while the second spinel CF is covered by 5/8 monolayer (ML) O*, exhibiting considerable affinity toward the oxygen species involved in the OER. Analysis based on advanced OER microkinetic volcano model indicates that a 5/8 ML O* covered-CF is the origin for the remarkable activity of this nanocomposite. The results reported here significantly advance knowledge in OER and can boost application, scale-up and commercialisation of electrocatalytic technologies toward clean energy devices.