Electrochemical Preparation of N‐Doped Cobalt Oxide Nanoparticles with High Electrocatalytic Activity for the Oxygen‐Reduction Reaction

Nitrogen-doped CoO (N-CoO) nanoparticles with high electrocatalytic activity for the oxygen-reduction reaction (ORR) were fabricated by electrochemical reduction of CoCl2 in acetonitrile solution at cathodic potentials. The initially generated, highly reactive nitrogen-doped Co nanoparticles were readily oxidized to N-CoO nanoparticles in air. In contrast to their N-free counterparts (CoO or Co3 O4 ), N-CoO nanoparticles with a N content of about 4.6 % exhibit remarkable ORR electrocatalytic activity, stability, and immunity to methanol crossover in an alkaline medium. The CoNx active sites in the CoO nanoparticles are held responsible for the high ORR activity. This work opens a new path for the preparation of nitrogen-doped transition metal oxide nanomaterials, which are promising electrocatalysts for fuel cells.