Cobalt nitride nanoparticle-modified nitrogen-doped graphene aerogel used as an efficient catalyst for oxygen reduction reaction in acidic medium

A promising cobalt nitride nanoparticle-modified nitrogen-doped graphene aerogel (CoN-NGA) has been prepared by chemical reduction and thermal treatment for oxygen reduction reaction (ORR). X-ray diffractometry result reveals the presence of cobalt nitride (CoN) nanoparticles on aerogel. X-ray photoelectron spectroscopy analyses reveal that nitrogen atoms have been doped into framework of graphene sheet and nitrogen-doped graphene sheets have been modified with cobalt nitride nanoparticles through CoN-C moieties. Analyses of scanning electron microscopy and Brunauer-Emmett-Teller show that CoN-NGA catalyst displays a various and interconnected pore structure. Because of a huge synergistic effect of the nitrogen-doped graphene, the three-dimensional porous structure and cobalt nitride nanoparticles, the prepared CoN-NGA catalyst displays comparable electrocatalytic activity and the similar onset potential as commercial Pt/C (20% loading). CoN-NGA catalyst exhibits superior stability and excellent methanol tolerance in acidic solution. Nitrogen-doped graphene has been provided positive potential and excellent methanol tolerance through functionalizing with cobalt nitride nanoparticles, because there are strong interactions between N-doped graphene and CoN nanoparticles through CoN-C moieties. It is found that CoN-C moieties are actual ORR active sites rather than CoN nanoparticles themselves. The possible mechanism of ORR on CoN-C moieties has been involved. This study demonstrates a feasible strategy to design non-precious metal nitride-modified heteroatom-doped graphene electrocatalyst for ORR in acidic electrolyte.