CoO nanoparticles anchored on nitrogen-doped reduced graphene oxide as a multifunctional catalyst for HO reduction, oxygen reduction and evolution reaction.

This study describes a facile and effective route to synthesize hybrid material consisting of CoO nanoparticles anchored on nitrogen-doped reduced graphene oxide (CoO/N-rGO) as a high-performance tri-functional catalyst for oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and HO sensing. Electrocatalytic activity of CoO/N-rGO to hydrogen peroxide reduction was tested by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry. Under a reduction potential at -0.6 V to HO, this constructing HO sensor exhibits a linear response ranging from 0.2 to 17.5 mM with a detection limit to be 0.1 mM. Although CoO/rGO or nitrogen-doped reduced graphene oxide (N-rGO) alone has little catalytic activity, the CoO/N-rGO exhibits high ORR activity. The CoO/N-rGO hybrid demonstrates satisfied catalytic activity with ORR peak potential to be -0.26 V (vs. Ag/AgCl) and the number of electron transfer number is 3.4, but superior stability to Pt/C in alkaline solutions. The same hybrid is also highly active for OER with the onset potential, current density and Tafel slope to be better than Pt/C. The unusual catalytic activity of CoO/N-rGO for hydrogen peroxide reduction, ORR and OER may be ascribed to synergetic chemical coupling effects between CoO, nitrogen and graphene.