Oxygen evolution on well-characterized mass-selected Ru and RuO2 nanoparticles

Well-defined mass-selected Ru and RuO 2 nanoparticles exhibit an order of magnitude improvement in the oxygen evolution activity, relative to the state-of-the-art, with a maximum at around 3–5 nm. Oxygen evolution was investigated on model, mass-selected RuO 2 nanoparticles in acid, prepared by magnetron sputtering. Our investigations include electrochemical measurements, electron microscopy, scanning tunneling microscopy and X-ray photoelectron spectroscopy. We show that the stability and activity of nanoparticulate RuO 2 is highly sensitive to its surface pretreatment. At 0.25 V overpotential, the catalysts show a mass activity of up to 0.6 A mg –1 and a turnover frequency of 0.65 s –1 , one order of magnitude higher than the current state-of-the-art.