Water Oxidation Catalyzed by Cobalt(II) Adsorbed on Silica Nanoparticles

Abstract

A novel, highly efficient, and stable water oxidation catalyst was prepared by a pH-controlled adsorption of Co­(II) on ∼10 nm diameter silica nanoparticles. A <i>lower limit</i> of ∼300 s^–1 per cobalt atom for the catalyst turnover frequency in oxygen evolution was estimated, which attests to a very high catalytic activity. Electron microscopy revealed that cobalt is adsorbed on the SiO₂ nanoparticle surfaces as small (1–2 nm) clusters of Co­(OH)₂. This catalyst is optically transparent over the entire UV–vis range and is thus suitable for mechanistic investigations by time-resolved spectroscopic techniques