Evidence for oxygen reduction reaction activity of a Ni(OH)2/graphene oxide catalyst

Abstract

Oxygen reduction reaction catalysis on a microwave synthesized Ni(OH)₂/graphene oxide material was investigated via cyclic voltammetry, rotating disk electrode measurements, chronoamperometry, and electrochemical impedance spectroscopy. Cyclic voltammetry in an 0.5 M alkaline solution indicated that the Ni(OH)₂/graphene oxide material possesses significant oxygen reduction reaction activity as evidenced by a peak potential of −310 mV vs. Ag/AgCl. This value was a shift of +110 mV as compared to the unsupported Ni(OH)₂ nanoparticles and +90 mV as compared to the graphene oxide support alone. Rotating disk electrode studies show that the limiting current density of the Ni(OH)₂/GO catalyst is 1.3 mA cm⁻² and the electron transfer number is 3.5. Chronoamperometry demonstrates that the current density attributable to the oxygen reduction reaction on the Ni(OH)₂/graphene oxide material sustained a steady state value of 60% of its initial value. Electrochemical Impedance spectroscopy showed that the charge transfer resistance of the Ni(OH)₂/graphene oxide catalyst was significantly lower than either the Ni(OH)₂ nanoparticles or the graphene oxide support. The electrocatalytic properties of the Ni(OH₎₂/graphene oxide material are discussed in the context of specific chemical interaction between the Ni(OH)₂ nanoparticles and the graphene oxide support.