Enhanced Oxygen Evolution Activity at Amorphous Hydroxide/Perovskite Interfaces

With increasing focus on sustainable development and clean energy, water electrolysis for hydrogen production is gaining attention as a green and renewable method. The oxygen evolution reaction (OER) at the anode, a four-electron transfer process, limits the efficiency of this reaction. In this work, we design an interface consisting of amorphous strontium-doped iron hydroxide (Sr–Fe(OH)x) and Ruddlesden–Popper (RP) type Sr3Fe2O7−δ perovskite (SFO7) via high concentration NaBH4 treatment. The formed catalyst (denoted as SFO7–S) offers a 180 mV overpotential at 10 mA cm–2 and an 18× activity enhancement at a 250 mV overpotential compared to the pristine SFO7. Electrochemical impedance spectroscopy measurements, tetramethylammonium (TMA+) tests, and in situ Raman spectroscopy studies reveal that the interfaces between amorphous Sr–Fe(OH)x and SFO7 perovskite facilitate intermediate adsorption and electron transfer, and thus enhancing the overall OER performance via the lattice oxygen pathway. In a membrane electrode assembly electrolyzer using 1 M KOH at 50 °C, SFO7–S achieves 200 h stable electrolysis at 300 mA cm–2 and 1.58 V with a cell degradation rate of 1.3 mV h–1.