Controllable Synthesis of Cobalt Monoxide Nanoparticles and the Size-Dependent Activity for Oxygen Reduction Reaction

Abstract

In this work, carbon-supported cobalt monoxides with an average size of 3.5, 4.9, and 6.5 nm are synthesized via a facile colloidal method avoiding any surfactants of long chains. Along with controlling the CoO particle size, we investigate the dependence of ORR activity on particle size of the CoO/C composite. It is discovered that the turnover frequency of the ORR per CoO site is largely independent of the particle size in the range of 3–7 nm, and the enhanced ORR activity for the smaller CoO particles is attributed to the enlarged interface between CoO and carbon.