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.