High electrochemical stability and low-agglomeration of defective Co3O4 nanoparticles supported on N-doped graphitic carbon nano-spheres for oxygen evolution reaction

The design of hybrid electrocatalysts with abundant active sites and long term stability is crucial for efficient oxygen evolution reaction (OER) application. Cobalt oxide is considered as one of the most promising electrocatalysts to replace noble metal due to its low cost, availability, and electrocatalytic activity towards the oxygen evolution reaction in alkaline media. However, nano-scale cobalt oxide suffers from severe surface self-agglomeration during the OER process, so that leading to poor activity and durability. Herein, ultra-small cobalt oxide nanoparticles are anchored on the surface of nitrogen doped porous 3D graphitic carbon nano-spheres (N-ACS@Co3O4) to increase the amount of exposed active site and avoid the self-agglomeration. The obtained electrocatalyst (N-ACS@Co3O4) is enriched with abundant oxygen vacancies and exhibits a superior OER activity (Overpotential of 237 mV at 10 mA.cm-2) and exceptional stability for at least 30 h in alkaline electrolyte (1 M KOH). The DFT calculations demonstrate that the strong adsorption of Co3O4 on N-doped graphene can prevent its agglomeration, and therefore improves the stability of Co3O4 nanoparticles during OER process in line with the experimental results.