DFT study of oxygen reduction reaction activity and stability on Mn-Ni dual-atom electrocatalysts anchored at graphene edges

In this study, we investigate the stability and oxygen reduction reaction (ORR) activity of dual-atom catalyst MnNiN₆ active sites on graphene basal planes and graphitic edge sites, utilizing a combination of density functional theory calculations, computational hydrogen electrode approximation, and microkinetic modelling. Our results reveal that graphitic edges enhance the formation and ORR activity of MnNiN₆ active sites. The ortho MnNiN₆ configuration demonstrates thermodynamic stability primarily in high-pH environments, whereas the para MnNiN₆ configuration is stable across a broader pH range, driven by O* and OH* intermediates formation, which poisons the active site at the initial ORR cycle. Moreover, the type of graphitic edge significantly influences ORR performance. Enhanced ORR activity is observed at armchair edges for ortho configurations, while para configurations show improved performance at OH-poisoned zig-zag edge sites.