Ultrafine iridium nanoparticles prepared without a surfactant for the acidic oxygen evolution reaction

Ultrafine metal Ir nanoparticles prepared by a surfactant-free synthesis method exhibit excellent OER activity in acidic media, with a low overpotential of 299 mV at 10 mA cm −2 and a high mass activity of 132 A g Ir −1 at 1.53 V vs. RHE.