CoN₃ embedded graphene, a potential catalyst for the oxygen reduction reaction from a theoretical perspective

Abstract

Non-precious metal catalysts have attracted particular interest in recent years due to their promising ORR (oxygen reduction reaction) activity in fuel cells. In this work, the structural stability and ORR mechanism of CoN₃ embedded graphene have been studied theoretically in acid media. The results indicate that CoN₃ embedded graphene is stable thermodynamically. The kinetically most favorable reaction pathway for the ORR is a four-electron process. The process of OOH hydrogenation to generate O + H₂O is the most favorable pathway. In the rate determining step, the energy barrier is 0.38 eV, much smaller than the theoretical value of ∼0.80 eV for pure Pt. The predicted working potential is 0.4 V for the most favorite pathway. Besides the lower energy barrier, the smaller Tafel slope compared with pure Pt in both low and high overpotential regions also suggests that CoN₃ embedded graphene is a promising electrocatalyst for the ORR.