Surface Tip Effects Enhanced Performance of Proton Exchange Membrane Water Electrolyzers

IrO₂ is widely used as a benchmarking anode catalyst in a proton exchange membrane water electrolyzer (PEMWE) but suffers from insufficient activity. We report an urchin-like IrRuO_x catalyst synthesized by a one-step hydrothermal method, which exhibits impressive oxygen evolution reaction activity and stability. In a PEMWE device, it achieves a current density of 6.4 A cm^-2 at 2 V with an Ir loading of only 0.2 mg cm^-2. Notably, the catalyst also exhibits exceptional stability, operating over 1000 h at 1.0 A cm^-2. Dynamic testing between 0.1 and 3.0 A cm^-2 further demonstrates its superior stability. This outstanding performance is primarily attributed to the unique tip effect of the urchin-like structure, enhancing areal current density and improving kinetics. This work advances the concept of catalyst surface morphology design and construction, demonstrating a practical advantage of morphology-driven enhancements, which is a feasible strategy for PEMWE to industrial applications.