Co₃O₄ nanoparticles anchored on nitrogen-doped reduced graphene oxide as a multifunctional catalyst for H₂O₂...

This study describes a facile and effective route to synthesize hybrid material consisting of Co₃O₄ nanoparticles anchored on nitrogen-doped reduced graphene oxide (Co₃O₄/N-rGO) as a high-performance tri-functional catalyst for oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and H₂O₂ sensing. Electrocatalytic activity of Co₃O₄/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 H₂O₂, this constructing H₂O₂ sensor exhibits a linear response ranging from 0.2 to 17.5 mM with a detection limit to be 0.1 mM. Although Co₃O₄/rGO or nitrogen-doped reduced graphene oxide (N-rGO) alone has little catalytic activity, the Co₃O₄/N-rGO exhibits high ORR activity. The Co₃O₄/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 Co₃O₄/N-rGO for hydrogen peroxide reduction, ORR and OER may be ascribed to synergetic chemical coupling effects between Co₃O₄, nitrogen and graphene.