Metal-organic gel-derived Fe-Fe2O3@nitrogen-doped-carbon nanoparticles anchored on nitrogen-doped carbon nanotubes as a highly effective catalyst for oxygen reduction reaction

A urea/carbon nanotubes (CNTs)-decorated metal-organic gel(Fe) was used as self-sacrifice precursors to prepare nano-sized Fe-Fe 2 O 3 @N-doped-C(NC) particles scattered on N-doped CNTs (NCNTs) through pyrolysis at 700   °C in N 2 . The particles with average size of ∼10   nm have core@shell structures with Fe-Fe 2 O 3 cores and NC shells, and the Fe-Fe 2 O 3 cores effectively connect with the NCNT scaffolds via the NC shells. Such a unique structure makes the material a superior oxygen reduction catalyst with an early onset potential (0.92   V), an early half-wave potential (0.72   V), a high current retention (91.7%, after 20,000   s), and good methanol tolerance in an alkaline electrolyte, enabling the catalyst the best among the developed Fe-FeO x oxygen reduction catalysts.