Active Sites Regulation\nand Mass Production of a Hierarchically\nPorous Fe–N–C Catalyst for Zinc–Air Batteries

Although the iron–nitrogen–carbon (Fe–N–C)\ncatalyst has great potential in zinc–air batteries (ZABs),\nthe insufficient performance and low production of the Fe–N–C\ncatalyst are still the key factors that greatly limit the commercial\napplication. In this study, first, a simple dual melt-salt template\nmethod is developed to prepare the hierarchically porous HPFe–N–C\ncatalyst with abundant highly stable Fe-pyridinic-N sites. Then, HPFe–N–C\nand Fe-phenanthroline are mixed and heated for the mass production\nof THPFe–N–C with rich highly active Fe-pyrrolic-N sites.\nUnder the synergistic effect of the different active sites, THPFe–N–C\nexhibits better activity and stability of oxygen reduction reaction\n(ORR) than Pt/C. Density functional theory is utilized to reveal the\nchanging of the free energy for the ORR process of active sites. COMSOL\nmultiphysics simulations are used to prove that the hierarchically\nporous THPFe–N–C is beneficial to the O<sub>2</sub> mass-transfer\nprocess. Therefore, THPFe–N–C shows a better discharge\nperformance and peak power density than Pt/C in the ZABs.