Amorphous TiO _x Overcoating Triggers the Dynamic Embedding of IrO _x Cluster for Efficient Acidic Water Oxidation

ABSTRACT The large‐scale deployment of proton exchange membrane water electrolyzers (PEMWEs) is hindered by the scarcity and instability of iridium‐based oxides (IrO x ) catalysts during the acidic oxygen evolution reaction. Herein, we report a dynamic embedding strategy to construct highly stable and active low‐iridium catalysts, which enables controlled incorporation of IrO x nanoclusters (NCs) into an amorphous TiO x overcoating supported on carbon nanotubes (IrO x /TiO x @CNT). Combined experimental and theoretical studies reveal that the dynamic embedding process enables coordinated growth kinetics, facilitating continuous anchoring of IrO x NCs within the flexible amorphous TiO x matrix. The resulting strong IrO x ‐TiO x interaction promotes significant electron transfer from TiO x to IrO x , thereby optimizing the adsorption energetics of oxygen intermediates and suppressing IrO x dissolution. The optimized catalyst achieves an exceptionally low overpotential of 258 mV at 10 mA cm −2 and outstanding durability in 0.5 m H 2 SO 4 . In PEMWE, the catalyst enables a cell voltage of 1.70 V at 1.0 A cm −2 with an ultralow Ir loading (0.3 mg cm −2 ), coupled with low energy consumption (45 kWh kg −1 H 2 ) and hydrogen production cost (∼$0.9 kg −1 H 2 ). This work underscores the pivotal role of amorphous overlayers in creating dynamically stable interfaces for advanced electrocatalysis.