【摘 要】
：
Non-noble-metal-based electrocatalysts with superior oxygen reduction reaction (ORR) activity to plat-inum (Pt) are highly desirable but their fabrications are challenging and thus impeding their applications in metal-air batteries and fuel cells.Here,we
【机 构】
：
Taishan Scholar Advantage and Characteristic Discipline Team of Eco Chemical Process and Technology,
论文部分内容阅读
Non-noble-metal-based electrocatalysts with superior oxygen reduction reaction (ORR) activity to plat-inum (Pt) are highly desirable but their fabrications are challenging and thus impeding their applications in metal-air batteries and fuel cells.Here,we report a facile molten salt assisted two-step pyrolysis strat-egy to construct carbon nanosheets matrix with uniformly dispersed Fe3N/Fe nanoparticles and abundant nitrogen-coordinated Fe single atom moieties (Fe@FeSA-N-C).Thermal exfoliation and etching effect of molten salt contribute to the formation of carbon nanosheets with high porosity,large surface area and abundant uniformly immobilized active sites.Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image,X-ray absorption fine spectroscopy,and X-ray photoelectron spectroscopy indicate the generation of Fe (mainly Fe3N/Fe) and FeSA-N-C moi-eties,which account for the catalytic activity for ORR.Further study on modulating the crystal structure and composition of Fe3N/Fe nanoparticles reveals that proper chemical environment of Fe in Fe3N/Fe notably optimizes the ORR activity.Consequently,the presence of abundant FeSA-N-C moieties,and potential synergies of Fe3N/Fe nanoparticles and carbon shells,markedly promote the reaction kinetics.The as-developed Fe@FeSA-N-C-900 electrocatalyst displays superior ORR performance with a half-wave potential (E1/2) of 0.83 V versus reversible hydrogen electrode (RHE) and a diffusion limited current den-sity of 5.6 mA cm-2.In addition,a rechargeable Zn-air battery device assembled by the Fe@FeSA-N-C-900 possesses remarkably stable performance with a small voltage gap without obvious voltage loss after 500 h of operation.The facile synthesis strategy for the high-performance composites represents another viable avenue to stable and low-cost electrocatalysts for ORR catalysis.
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