Nanosized Pd-loaded the Fe3C encapsulated by N-doped carbon nanotube as an electrocatalyst for oxygen reduction and ethanol oxidation reactions

Abstract

Iron carbide-encapsulated nitrogen-doped carbon nanotubes (Fe3C@NCNTs) and Pd that is loaded onto Fe3C@NCNTs (Pd/Fe3C@NCNTs) electrocatalysts were synthesized. The valence state of Pd that was loaded onto the Pd/Fe3C@NCNTs surface is in the Pd0 and Pd2+ forms and Pd0 is the main form. The electrochemical measurement results imply that the Fe3C@NCNT catalyst exhibits an electrocatalytic property in the oxygen reduction reaction (ORR). The Pd/Fe3C@NCNT electrocatalyst has a good catalytic property toward ORR and ethanol oxidation reaction (EOR) in an alkaline solution. The half-wave potential (E1/2) on the Pd/Fe3C@NCNT electrocatalyst toward the ORR can reach 0.904 V, which is higher than that on commercial 20 wt% Pt/C (0.856 V). The forward oxidation peak current density (jf) on the Pd/Fe3C@NCNT electrocatalyst for ethanol oxidation is 1.655 A mg−1, which is larger than that on commercial 10 wt% Pd/C (0.430 A mg−1). The excellent electrocatalytic property of the Pd/Fe3C@NCNT electrocatalyst is contributed to the many active sites and synergistic effects between Pd and Fe3C@NCNTs. The density functional theory (DFT) calculation result implies that the electron mobility increases in the recombination area for Pd and Fe3C@NCNTs.