The exploration of highly efficient catalysts to replace noble metal platinum for the oxygen reduction reaction, on which M/N/C catalysts have shed brilliant light, is greatly significant but challenging. This… Click to show full abstract
The exploration of highly efficient catalysts to replace noble metal platinum for the oxygen reduction reaction, on which M/N/C catalysts have shed brilliant light, is greatly significant but challenging. This paper presents a strategy for synthesizing highly efficient and stabilized hollow structure Fe/N/C catalysts with iron and nitrogen doped into the carbon layer by the self-template method. The prepared Fe/N/C catalysts with NaCl protection during pyrolysis are characterized by a unique hollow structure, porous morphology and Fe–N coordination as the active sites, all of which significantly endow the materials with excellent properties towards the ORR, including high electrical conductivity, long-term durability and outstanding capacity for methanol tolerance. We employed X-ray absorption fine structure spectrometry to investigate the chemical state and coordination environment of the central iron atoms of the Fe/N/C catalysts, which also clarified the promoting effect of the NaCl protection for Fe–N coordination during pyrolysis. In particular, the Fe/N/C catalysts exhibit positive half-wave potentials (0.84 V vs. RHE) and Tafel slope comparable to 20% commercial Pt/C, possessing four-electron transfer pathway as well as excellent long-term stability and methanol tolerance in alkaline medium.
               
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