Co-synthesis of atomic Fe and few-layer graphene towards superior ORR electrocatalyst

Large-scale synthesis of either single-metal atom catalyst or graphene from graphite direct exfoliation at high yield is quite challenging. Here we demonstrated a scalable electrochemical approach to synthesize few-layer graphene flakes and isolated Fe atoms at the same time. It was found that graphite could be expanded in FeCl4--based ionic liquid at a low potential of 2 V. Fe isolated onto graphene resulted from electrochemical reactions of FeCl4--based intercalates. After annealing at the presence of nitrogen source, atomic Fe isolation was kept and coordinated with nitrogen. The paintable atomic layer material exhibited superior oxygen reduction reaction performance to Pt/C. The catalytic activity could be enhanced 30 times per gram and 100 times per metal atom, if Fe-Nx/graphene was compared with Pt/C (20 wt.% Pt) on the basis of metal content.