Framework-derived Ir–doped Co3O4 to a reconstructed, self-preserving surface for stable acidic oxygen evolution

The scarcity of iridium demands efficient catalysts for the acidic oxygen evolution reaction in proton-exchange membrane water electrolyzers (PEMWE). This study reports a highly active and durable catalyst synthesized through a direct one-step doping of iridium into a cobalt-based zeolitic imidazolate framework (ZIF-67), followed by thermal conversion. This approach embeds iridium species within the resulting porous cobalt oxide lattice (Ir x% CoO δ ). The optimal Ir 5% CoO δ catalyst shows excellent performance in 0.1 M HClO 4 , requiring an overpotential of only 284 mV at 10 mA cm −2 and a low Tafel slope of 44.8 mV dec −1 , while demonstrating superior long-term stability over commercial IrO 2 . In a full-cell configuration with a Pt/C cathode (Ir 5% CoO δ || Pt/C), a cell voltage of only 1.565 V is required at 10 mA cm −2 , outperforming the IrO 2 || Pt/C benchmark with excellent durability. Gas quantification measurements confirmed a Faradaic efficiency of >97% for overall water splitting, validating the high charge-to-fuel conversion efficiency. Post-reaction analysis reveals that this stability arises from a synergistic surface transformation during operation: the catalyst surface reconstructs into nanocrystalline IrO 2 domains supported by a stable Co 3 O 4 scaffold. This composite structure prevents Ir agglomeration while the active layer resists acidic corrosion, creating a self-preserving interface. Furthermore, under industrially relevant PEMWE conditions, Ir 5% CoO δ achieved a cell voltage of only 2.0 V at 1 A cm −2 and maintained stable operation for over 100 h at 200 mA cm −2 with minimal degradation and no detectable metal leaching. This work provides a high-performance, low-iridium catalyst and establishes a generalizable strategy for framework-level doping and electrochemical interface engineering.