Self-supported amorphous iridium oxide catalysts for highly efficient and durable oxygen evolution reaction in acidic media

• A novel electrodeposition method is developed to prepare self-supported amorphous IrO x /Ti electrode. • Pre-activation plays a significant role in in-situ constructing an amorphous film. • The amorphous IrO x film exposes high contents of active Ir III species and surface hydroxides to enhance the OER performance. • Amorphous-crystalline synergy and rich interface contribute to the superior stability and activity. • A super durability for 190 h at 10 mA cm −2 and 50 mA cm −2 was achieved for amorphous IrO x -50/Ti. Developing highly active and stable electrocatalysts for acidic oxygen evolution reaction is still a great challenge. Herein, we developed a novel self-supported amorphous IrO x catalyst (IrO x /Ti) encapsulated with a small number of crystalline nanoparticles for efficient acidic OER. The resulting IrO x -50-AC/Ti electrode exhibits a superior OER performance with an overpotential of 250 mV at 10 mA cm −2 and Tafel slope of 50.4 mV dec −1 in 0.1 M HClO 4 . High contents of Ir III species and surface hydroxide groups, hierarchically porous structure and high defective density contribute to boost the OER activity. Importantly, the amorphous IrO x -50-AC/Ti also demonstrates a super long-term durability for 190 h due to the strong interaction between IrO x film and Ti. The unique amorphous-crystalline structure also enhances the stability and the activity by promoting the synergy between amorphous phase and crystalline phase. This work provides some valuable insights on developing efficient Ir-based catalysts for acidic water splitting. A novel self-supported amorphous IrO x catalyst (IrO x /Ti) is developed by an electrodeposition strategy for efficient acidic OER. The optimized amorphous IrO x -50-AC/Ti demonstrates a super long-term durability for 190 h and an excellent activity with an overpotential of 250 mV to obtain 10 mA cm −2 in 0.1 M HClO 4 .