Hybrid perovskites as oxygen evolution electrocatalysts for high-performance anion exchange membrane water electrolyzers

Highly active and platinum group metal-free (PGM-free) oxygen evolution reaction (OER) electrocatalysts are essential for producing low-cost and clean hydrogen in anion exchange membrane water electrolyzers (AEMWEs). Thanks to the unique characteristics of perovskite oxides, which include low cost, tunable electronic structure and cation deficiency, high electronic conductivity, high durability, high specific catalytic activity, and environmental friendliness, they have been widely designed and employed as the OER electrocatalysts. Here, a set of novel hybrid perovskites, La x Sr 4-x Ni y Fe 3-y O 10-δ (L x S 4-x N y F 3-y ), were demonstrated, which consist of a single-layer perovskite phase (P phase) and two Ruddlesden–Popper perovskite phases (RP phases). These hybrid perovskites synergize the advantages of the P phase and RP phases, which improves the oxygen-ion diffusion rate, leading to enhanced OER activity. Furthermore, the concentration of each phase can be tuned by alternating the compositional stoichiometry. A relatively uniform distribution of the P phase and RP phases can maximize the interfacial area and achieve the highest oxygen-ion diffusion rate. L 3 S 1 N 2 F 1, L 2 S 2 N 1 F 2, and L 2 S 2 N 1.5 F 1.5 exhibit outstanding OER activity, which achieve 10 mA/cm 2 at a low overpotential of less than 360 mV in 1.0 M KOH. Additionally, herein, the hybrid perovskites are implemented as the anodes of AEMWEs, which deliver an exceptional current density of > 1.0 A/cm 2 at 1.8 V.