Feasibility of Active and Durable Lattice Oxygen‐Mediated Oxygen Evolution Electrocatalysts in Proton Exchange Membrane Water Electrolyzers Through d⁰ Metal Ion Incorporation

The primary hurdle faced in the practical application of proton exchange membrane water electrolyzer (PEMWE) involves improving the intrinsic kinetic activity of oxygen evolution reaction (OER) electrocatalysts while concurrently enhancing their durability. Although electrocatalysts based on lattice oxygen-mediated mechanism (LOM) have the potential to significantly enhance the activity in OER without being restricted by scaling relationships, they are neglected in acidic electrolytes due to limited durability. In this study, an innovative approach is presented to simultaneously promote the activation of lattice oxygen and improve the durability of LOM-based OER electrocatalysts by incorporating d⁰ metal ions into the RuO₂ electrocatalyst. Leveraging the unique electronic properties of the d⁰ metal ion, the O 2p band center and Ru-O covalency of the electrocatalyst are successfully engineered, resulting in the change in OER mechanism. Furthermore, in a single cell of PEMWE, the LOM-based electrocatalyst demonstrates outstanding performance, achieving 3.0 A cm^-2 at 1.81 V and maintaining durability for 100 h at 200 mA cm^-2, surpassing commercial RuO₂. This innovative strategy challenges the traditional viewpoint that suppressing lattice oxygen activation in OER is essential for enhancing PEMWE durability, offering new perspectives for the development of OER electrocatalysts in acidic electrolytes.