Amorphous TiOx Overcoating Triggers the Dynamic Embedding of IrOx Cluster for Efficient Acidic Water Oxidation

The large-scale deployment of proton exchange membrane water electrolyzers (PEMWEs) is hindered by the scarcity and instability of iridium-based oxides (IrOx) 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 IrOx nanoclusters (NCs) into an amorphous TiOx overcoating supported on carbon nanotubes (IrOx/TiOx@CNT). Combined experimental and theoretical studies reveal that the dynamic embedding process enables coordinated growth kinetics, facilitating continuous anchoring of IrOx NCs within the flexible amorphous TiOx matrix. The resulting strong IrOx-TiOx interaction promotes significant electron transfer from TiOx to IrOx, thereby optimizing the adsorption energetics of oxygen intermediates and suppressing IrOx dissolution. The optimized catalyst achieves an exceptionally low overpotential of 258 mV at 10 mA cm−2 and outstanding durability in 0.5 m H2SO4. 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 H2) and hydrogen production cost (∼$0.9 kg−1 H2). This work underscores the pivotal role of amorphous overlayers in creating dynamically stable interfaces for advanced electrocatalysis.