Enhanced dual atomic Fe-Ni sites in N-doped carbon for bifunctional oxygen electrocatalysis

Abstract

Atomically dispersed catalysts with high electrocatalytic performance are emerging as promising elec-trocatalysts for energy conversion and storage devices. Nevertheless, achieving superior bifunctional catalytic activity with single-atom catalysts toward reactions involving multi-intermediates is still facing great challenges. Herein, dual-atomic Fe-Ni pairs dispersed in hierarchical porous nitrogen-doped carbon (FeNi-HPNC) catalysts were successfully synthesized using a facile mechanochemical strategy. By virtue of the engineered electronic structure of Fe coordinated with Ni, the as-synthesized FeNi-HPNC with atomically dispersed dual-metal active sites and pore-rich structure exhibits remarkable bifunctional activities. A high half-wave potential of 0.868 V for oxygen reduction reaction and a low potential of 1.59 V at 10 mA/cm2 for oxygen evolution reaction have been obtained for FeNi-HPNC, which are superior to the single-atom catalysts of Fe-HPNC and Ni-HPNC, respectively, and are even greater than the precious metal catalysts. Combined experimental and theoretical results have revealed that the enhanced bifunctional catalytic activity of FeNi-HPNC is ascribed to the electronic interaction of Fe-Ni sites, which decreases the adsorption energy of oxygen intermediates during oxygen reduction reac-tion/oxygen evolution reaction. Furthermore, the practical application of FeNi-HPNC catalysts in Zn-air batteries has been demonstrated; a high peak power density and long-term durability are delivered.