The activities of the oxygen evolution reaction (OER) on iridium-oxide- and ruthenium-oxide-based catalysts are among the highest known to date. However, the OER activities of thermodynamically stable rutile iridium oxide (r-IrO2) and rutile iridium oxide (r-RuO2), normalized to catalyst mass or true surface area are not well-defined. Here we report a synthesis of r-IrO2 and r-RuO2 nanoparticles (NPs) of ∼6 nm, and examine their OER activities in acid and alkaline solutions. Both r-IrO2 and r-RuO2 NPs were highly active for OER, with r-RuO2 exhibiting up to 10 A/goxide at 1.48 V versus reversible hydrogen electrode. When comparing the two, r-RuO2 NPs were found to have slightly higher intrinsic and mass OER activities than r-IrO2 in both acid and basic solutions. Interestingly, these oxide NPs showed higher stability under OER conditions than commercial Ru/C and Ir/C catalysts. Our study shows that these r-RuO2 and r-IrO2 NPs can serve as a benchmark in the development of active OER catalysts for electrolyzers, metal-air batteries, and photoelectrochemical water splitting applications.

We report the structure-controlled synthesis of FePt/MgO NPs and their catalysis for oxygen reduction reaction (ORR) in 0.5 M H(2)SO(4) solution. The synthesis yields fcc-FePt/MgO and fct-FePt/MgO NPs with the MgO coating being readily removed for catalytic studies. The fct-FePt NPs show higher activity and durability than the fcc-FePt in the ORR condition. The results indicate that the fully ordered fct-FePt could serve as a practical Pt-based catalyst for fuel cell applications.

Monodisperse 8 nm Pt nanocubes are synthesized by reducing Pt(acac)2 in the presence of oleic acid, oleylamine, and a trace amount of Fe(CO)5. Self-assembly of these nanocubes results in a (100) textured array. The nanocubes show an enhanced catalysis toward oxygen reduction, and their specific activity is over twice as high as that from the commercial Pt nanoparticles.