Boosting oxygen reduction catalysis by introducing Fe bridging atoms between Pt nanoparticles and N-doped graphene

Introducing heterometals into Pt/C catalyst to construct multi-metal catalyst for improving the intrinsic activity is a rational strategy which can optimize the over-strong *O adsorption of Pt nanoparticles for oxygen reduction reaction (ORR). However, the practical activity and stability of such carbon supported Pt-based bimetallic catalysts are simultaneously limited by the conductivity degradation and deactivation caused by the weaker interaction between Pt and carbon support. Herein, by taking advantage of the precise control and self-limiting reaction of atomic layer deposition, we construct a novel Pt-Fe-NG structure in which Fe atoms play the bridging role between Pt nanoparticles and the N-doped graphene by multistep deposition. Impressively, the obtained catalyst exhibits an outstanding ORR half-wave potential of 0.948 V, a total four-electron pathway and superior durability over 10,000 cycles. The mass activity of the catalyst at 0.9 V is 15 times higher than that of commercial Pt/C. Moreover, when used as the cathode catalyst of Zn-air battery, the Pt-Fe-NG performs a maximum density power of 230 mW cm-2 and excellent stability after 180 discharge-charge cycles. The experimental results and theoretical calculations indicate that Fe bridging atoms play the role of elevating the d-band center of Pt nanoparticles and enhancing the interaction between Pt nanoparticles and carbon support, which paves a pathway for constructing novel multi-metal catalysts.