Seed-Mediated Growth of Mesoporous Pyrochlore for Efficient and Durable Acidic Oxygen Evolution

Proton exchange membrane water electrolysis (PEMWE) is a promising route to hydrogen, yet sluggish anodic oxygen evolution reaction (OER) kinetics and durability limitations in acidic media still constrain device efficiency and lifetime. Here we report Y 2 Ir 1.2 Ru 0.8 O 7, a pyrochlore catalyst in which dual active sites are precisely constructed at the B site via seed-mediated growth, enabling concurrent high activity and durability for acidic OER. The mesoporous nanosphere architecture creates a superhydrophilic, high surface area microenvironment that improves mass transport and facilitates bubble detachment. In 0.1 M HClO 4, the catalyst requires only 227 mV overpotential at 10 mA cm –2 and the cell voltage rises by about 20 mV after 1200 h of continuous operation. Operando characterization (FTIR/ 18 O–DEMS) combined with DFT results indicates that the OER on Y 2 Ir 1.2 Ru 0.8 O 7 follows an oxide pathway mechanism (OPM), thereby validating the feasibility of OPM at B site dual active centers in the pyrochlore structure. Notably, Y 2 Ir 1.2 Ru 0.8 O 7 supports direct coupling of *O–*O radicals during OER, thereby avoiding the formation of *OOH. A PEMWE cell using Y 2 Ir 1.2 Ru 0.8 O 7 as the anode maintains stability for more than 200 h at 2 A cm –2, indicating potential for scale up. This work provides a generalizable structure-mechanism codesign strategy for high performance, long-lived acidic OER catalysts tailored to PEMWE.