Abstract
Reasonable design and scalable preparation of low-cost, effective and durable electro-catalysts as substitutes to expensive Pt-derived catalysts for oxygen reduction reaction (ORR) is highly desired toward the progress of future sustainable energy storage devices. In this work, we scalably prepare a highly active ORR electrocatalyst which consists of both Fe3N nanoparticles and Fe-N-C active sites in N-doped carbon frameworks (named as Fe3N/Fe-N-C) and derives from walnut shells as precursors followed by iron ion incorporation and a pyrolysis process in NH3 atmosphere. The X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopic (XPS) measurements strongly evidence the coexistence of Fe3N nanoparticles and iron-nitrogen-carbon active sites. Benefiting from the synergistic mechanism between Fe3N nanoparticles and Fe-N-C sites in N-doped carbon frameworks, the resultant catalyst presents desirable ORR performance with impressive E-onset, E-1/2, higher long-term stability, and satisfactory resistance to methanol interference, overtopping commercial Pt/C catalyst. The present research not only proposes a cost-effective and available ORR electro-catalyst to substitute Pt-based catalysts, but also provides a reliable and versatile technology to realize large-scale preparation for practical applications. (C) 2020 Published by Elsevier Inc.