Green Synthesis of a Highly Efficient and Stable Single-Atom Iron Catalyst Anchored on Nitrogen-Doped Carbon Nanorods for the Oxygen Reduction Reaction

The synthesis of inexpensive and efficient electrocatalysts with an excellent stability for the electrochemical oxygen reduction reaction (ORR) in both alkaline and acid media through a facile environment-friendly strategy is extremely desirable but remains challenging. In this study, a single-atom iron electrocatalyst with exclusively Fe–N4 moieties anchored on nitrogen-doped carbon nanorods (denoted as Fe–SA/NCS) is synthesized through a one-step pyrolysis of Fe-doped zeolitic imidazole framework-8 (ZIF8) nanorods that are synthesized in an aqueous system without acid leaching assistance. Profiting from the synergistic effect of the hierarchically porous carbon support with a rodlike structure and the large number of Fe–N4 moieties, the newly prepared Fe–SA/NCS exhibits excellent ORR catalysis activities with a half-wave potential of 0.91 V vs RHE in 0.1 M KOH as well as 0.77 V vs RHE in 0.1 M HClO4. Furthermore, better stability in alkaline or acid conditions was also observed for Fe–SA/NCS compared with Pt/C. The high open-circuit voltage of 1.53 V and high power density of 141.6 mW cm–2 of a zinc–air battery (ZAB) with Fe–SA/NCS as the cathode material indicate excellent electrochemical performances. The ZAB with the Fe–SA/NCS catalysts exhibits a remarkable cycling performance for more than 300 h with a high voltaic efficiency of 78.6%. The present work could pave the way for the rational construction of highly efficient and stable single-atom electrocatalysts through green synthesis for sustainable energy technologies.