Cobalt oxide nanocomposites and their electrocatalytic behavior for oxygen evolution reaction

In this work, we have described the simple preparation method of cobalt oxide nanocomposites where cobalt oxide nanoparticles were grown on the surface of carbon nanotube, graphene oxide and graphene (Co3O4@CNT, Co3O4@GO, Co3O4@G). The as-grown Co3O4@CNT, Co3O4@GO, Co3O4@G were investigated for H2O oxidation. The nanoparticles displayed high activity toward oxygen evolution. Further, the stability of the catalysts were tested in alkaline solution, which exhibited good stability. Among all nanoparticles, Co3O4@G exhibited higher current density at lower overpotential and also exhibited lower Tafel slope (157.1 mV dec−1) as compared to Co3O4@CNT and Co3O4@GO. The Co3O4@G delivered a current density of 10 mAcm−2 at 0.8 V (overpotential 535 V versus Ag/AgCl) in 0.1 M KOH solution, which is superior than many electrocatalysts reported for oxygen evolution so far. The good electrocatalytic performance might be due to the structural features of Co3O4@G, which cause enhancement of oxygen evolution activity.