Polyaniline engineering defect-induced nitrogen doped carbon-supported Co3O4 hybrid composite as a high-efficiency electrocatalyst for oxygen evolution reaction

[Display omitted] •The Co3O4/CN HNPs is successfully fabricated as high-efficiency OER electrocatalyst.•The Co3O4/CN HNPs has the advantages of high conductivity and exposed active sites.•The formation of Co-N bonds is instrumental in strengthening structural stability.•The existence of defects over Co3O4 nanoparticles is favorable for OER kinetics.•The Co3O4/CN HNPs presents excellent OER performance and unprecedented stability. The development of earth-abundance electrocatalyst with high performance for oxygen evolution reaction (OER) is of paramount importance in sustainable water splitting. Herein, the novel defect-induced nitrogen-doped carbon-supported Co3O4 nanoparticles is successfully fabricated as OER electrocatalyst (denoted as Co3O4/CN HNPs) through a wetness-impregnation treatment of Co/polyaniline (PANI) followed by a thermal annealing. This advanced architecture of Co3O4/CN HNPs can not only improve its conductivity and electrocatalytically active sites but also generate a large number of oxygen-vacancy defects and crystal defects, which effectively exert the preponderance in facilitating interfacial electronic transfer and optimizing the adsorption energy for intermediates, thus imparting the extraordinary activities in catalyzing OER. In addition, there are evidences demonstrating the formation of C-N coordination bonds through the strong interaction of the interconnected interface and the generation of pyridinic-N species after the annealing treatment, which enables the structural stability to get further strengthened and accelerates oxygen releasing for reduction of OER overpotential, respectively. Benefiting from the above desirable properties, the Co3O4/CN HNPs affords a lower overpotential of 290 mV at a current density of 10 mA cm−2 as compared to those of pure Co3O4 and PANI, outperforming commercial IrO2 and the representative Co3O4-based OER electrocatalysts as recently reported. Moreover, the Co3O4/CN HNPs also exhibits long durability with negligible activity degeneration at a current density of 10 mA cm−2 for 20 h. ̵.