Metal–organic frameworks-derived core–shell Fe₃O₄/Fe₃N@graphite carbon nanocomposites as excellent non-precious metal electrocatalyst for oxygen reduction

Abstract

Metal-organic frameworks (MOFs), as precursors for synthesizing new carbon materials, hold promise for applications in the oxygen reduction reaction (ORR) as efficient non-precious metal catalysts. Here, a facile template-assisted strategy was adopted to fabricate a core-shell structure derived from MIL-101(Fe) and polyaniline. MIL-101(Fe) nanoparticles obtained by microwave-assisted synthesis were combined with PAni in different ratios and carbonized at 900 °C under flowing N2. An optimized core-shell Fe3O4/Fe3N@graphite carbon structure was successfully prepared and exhibited attractive ORR activity, with a half-wave potential of 0.916 V vs. RHE and an electron transfer number of 4.0 at 0.4 V vs. RHE. Furthermore, the catalyst displayed excellent stability in an alkaline solution. The superior ORR performance of the catalyst is mainly attributed to its stable core-shell structure, large specific surface area and high content of electrocatalytically active N species.