Fig. 6
Zinc-air battery and hydrogen-air fuel cell performances. a The open circuit voltage curves of Zn-air batteries by applying single iron atomic sites supported on a nitrogen, phosphorus and sulfur co-doped hollow carbon polyhedron (Fe-SAs/NPS-HC) and 20 wt% Pt/C as the air cathode catalyst, respectively. b Discharging polarization curves and the corresponding power density plots of Fe-SAs/NPS-HC-based and 20 wt% Pt/C-based Zn-air batteries. c Charge−discharge cycling performance of Fe-SAs/NPS-HC-based and 20 wt% Pt/C-based Zn-air batteries. d H2-air fuel cell polarization curves and power density plots of membrane electrode assemblies (MEAs) using Fe-SAs/NPS-HC (loading of 0.8 mg cm−2) and 20 wt% Pt/C (loading of 0.8 mg cm−2) as cathode catalysts, respectively. Membrane Nafion 211, cell 60 °C, electrode area 5 cm2
