Plasma-engineered cobalt nanoparticle encapsulated N-doped graphene nanoplatelets as high-performance oxygen reduction reaction electrocatalysts for aluminum–air batteries

Abstract

The increasing demand for continuous and eco-friendly alternative energy has prompted interest in aluminum–air (Al–air) batteries owing to their high energy density and safety. On the other hand, the sluggish oxygen reduction reaction (ORR) rate in alkaline electrolytes, which adversely affects the efficiency of the Al–air battery, is still a challenge. A transition metal electrocatalyst consisting of cobalt nanoparticles encapsulated with N-doped graphene nanoplatelets (Co@N/GNP) was synthesized by plasma engineering. In this design, the active Co nanoparticle acted as the ORR active site and the core-shell structure of dominant pyridinic-N graphene led to outstanding catalytic performance (E1/2 = 0.87 V, Eonset = 0.98 V) in an alkaline electrolyte. Furthermore, when applied as a cathode catalyst in practical Al–air batteries, Co@N/GNP showed excellent performance with a peak power density of 143 mW cm-2.