Enhancing Heterointerface Coupling for Durable Industrial‐Level Proton Exchange Membrane Water Electrolysis

Abstract The industrial‐level application of proton exchange membrane water electrolysis (PEMWE) lies in the capacity of operating at high current density in order for higher power density and lower operational cost. However, it poses a significant challenge to the overall performance of catalysts. Heterointerface engineering has emerged as an ideal strategy for addressing the anodic intrinsic activity limitations. Nevertheless, due to the fragile interface structure with weak interactions between different components, it is difficult to maintain the high activity and long‐term stability of heterostructured catalysts. Herein, we report a ternary heterostructured catalyst, RuIrO x –CeO 2 , featuring a strong‐coupled interface between RuIrO x phase and CeO 2 phase. This strong‐coupled interface exhibits both electronic and oxygen interaction, which effectively inhibits the active phase separation. When applied in PEMWE (0.8 mg Ir  cm −2 for the anode and 0.4 mg Pt  cm −2 for the cathode), the resultant catalyst expresses impressive activity, achieving a current density of 3.0 A cm −2 at a cell voltage of 1.75 V in PEMWE and demonstrates a stable 2000‐h operation at 5.0 A cm −2 with an imperceptible voltage degradation of <1 µV h −1 .