Oxide-supported IrNiO_x core-shell particles as efficient, cost-effective, and stable catalysts for electrochemical water splitting

Active and highly stable oxide-supported IrNiO_x core-shell catalysts for electrochemical water splitting are presented. IrNi_x@IrO_x nanoparticles supported on high-surface-area mesoporous antimony-doped tin oxide (IrNiO_x/Meso-ATO) were synthesized from bimetallic IrNi_x precursor alloys (PA-IrNi_x/Meso-ATO) using electrochemical Ni leaching and concomitant Ir oxidation. Special emphasis was placed on Ni/NiO surface segregation under thermal treatment of the PA-IrNi_x/Meso-ATO as well as on the surface chemical state of the particle/oxide support interface. Combining a wide array of characterization methods, we uncovered the detrimental effect of segregated NiO phases on the water splitting activity of core-shell particles. The core-shell IrNiO_x/Meso-ATO catalyst displayed high water-splitting activity and unprecedented stability in acidic electrolyte providing substantial progress in the development of PEM electrolyzer anode catalysts with drastically reduced Ir loading and significantly enhanced durability.