The Synthesis And Performance Study Of Iron Embedded N-doped Carbon Composites

The iron embedded N-dopped carbon composites have attracted extensive attention of the researchers since the excellent oxygen reduction activity and microwave absorption.This paper focuses on the design and synthesis of iron nitrogen and carbon composites.The precursors of amino phenolic formaldehyde resin scattered with iron oxide?Fe₂O₃/APF?are obtained by simple hydrothermal treatment.The iron embedded N-dopped carbon composites are obtained through the heat treatment of precursors.The relationships between the microstructure,phase composition,the specific surface area,pore size distribution and the graphitization degree of iron nitrogen and carbon composites and oxygen reduction reaction?ORR?performance or microwave absorption were studied.An easily scalable and simple method is applied to prepare the iron embedded N-dopped carbon composites?Fe/N/C?ORR catalysts with the raw materials of3-aminophenol,hexamethylenetetramine and FeCl₃·6H₂O which have the highly activity and excellent stability.The precursors of amino phenolic formaldehyde resin scattered with iron oxide are obtained by simple hydrothermal treatment.The Fe/N/C composites with Fe-N_x configurations and graphene-encapsulated Fe nanoparticles are obtained synchronously by the heat treatment of 800 ^oC under the N₂ flowing.The catalysts display a highly activity with the half-wave potential(E_1/2)of 0.8 V?vs RHE?and 19%current density decay after 56700 s in 0.1 mol/L O₂-saturated KOH solution.The iron embedded N-dopped carbon composites are in-situ obtained through the heat treatment of the amino phenolic formaldehyde resin?APF?scattered with Fe₂O₃nanoparticles under the mixed atmosphere of 5 vol%H₂ and 95 vol%Ar,which was synchronously synthesized by the hydrothermal process with different molar ratio of3-aminophenol to FeCl₃·6H₂O?Fe-C?.The Fe nanoparticles uniformly embedded in carbon?Fe-C-e?was obtained with the molar ratio of 1:0.7,which reveals outstanding microwave absorption.The minimum reflection loss is-64.6 dB at 14.88 GHz and the effective absorption bandwidth?reflection loss of less than-10 dB?is 5.8 GHz with the matching thickness of 1.85 mm.The Fe particles randomly distributed outside the carbon?Fe-C-d?was obtained with the molar ratio of 1:1.The matching thickness is 3.55 mm with the effective absorption bandwidth of 3.18 GHz and the minimum reflection loss is-49.2 dB.The microwave absorption of Fe-C-w was obtained by acid etching to remove most of iron element of Fe-C-e.The matching thickness of Fe-C-w is 2.11 mm with the effective absorption bandwidth of 5.2 GHz and the minimum microwave absorption intensity is-54.4 dB.The microwave absorption of Fe/Fe₃O₄-C-e was obtained with the molar ratio of 1:0.7 under the N₂ flowing.The minimum reflection loss is-18.6 dB and the matching thickness is 3.55 mm with the effective absorption bandwidth of 3.2 GHz and the effective absorption bandwidth is only 2.7 GHz with the matching thickness of 2.00mm.