Immobilization of cobalt oxide nanoparticles on porous nitrogen-doped carbon as electrocatalyst for oxygen evolution

[Display omitted] Highly efficient and robust electrocatalysts have been in urgent demand for oxygen evolution reaction (OER). For this purpose, high-cost carbon materials, such as graphene and carbon nanotubes, have been used as supports to metal oxides to enhance their catalytic activity. We report here a new Co3O4-based catalyst with nitrogen-doped porous carbon material as the support, prepared by pyrolysis of porous polyurea (PU) with Co(NO3)2 immobilized on its surface. To this end, PU was first synthesized, without any additive, through a very simple one-step precipitation polymerization of toluene diisocyanate in a binary mixture of H2O-acetone at room temperature. By immersing PU in an aqueous solution of Co(NO3)2 at room temperature, a cobalt coordinated polymer composite, Co(NO3)2/PU, was obtained, which was heated at 500 °C in air for 2 h to get a hybrid, Co3O4/NC, consisting of Co3O4 nanocrystals and sp2-hybridized N-doped carbon. Using this Co3O4/NC as a catalyst in OER, a current density of 10 mA·cm−2 was readily achieved with a low overpotential of 293 mV with a Tafel slope of 87 mV·dec−1, a high catalytic activity. This high performance was well retained after 1000 recycled uses, demonstrating its good durability. This work provides therefore a facile yet simple pathway to fabrication of a new transition metal oxides-based N-doped carbon catalyst for OER with high performance.