In-situ Preparation of Pd Incorporated Ordered Mesoporous Carbon as Efficient Electrocatalyst for Oxygen Reduction Reaction

We develop a facile method for the synthesis of size-controlled nano-crystaline palladium incorporated into ordered mesoporous carbon (OMC) as oxygen reduction reaction (ORR) electrocatalyst, applied in the cathode of fuel cell and metal-air battery. The catalyst with 18 wt.% Pd in ordered mesoporous carbon, pyrolyzed at 900 °C shows excellent catalytic performance for ORR. The onset and half-wave potentials are 0.963 V and 0.872 V (vs. RHE) in 0.1 M KOH, respectively, which are comparable to those of commercial 30 wt.% Pt/C, 0.975 V and 0.854 V (vs. RHE). The catalyst with 12 wt.% Pd in ordered mesoporous carbon shows largest limiting current density when the current is normalized by the mass of noble metal. The efficient utilization of active Pd in the mesoporous carbon framework endows the catalyst an almost direct four-electron reduction pathway. The transferred electron number of 12Pd-OMC-900 is calculated to be 4.14 at 0.4 V (vs. RHE). Its excellent ORR activity should be ascribed to the optimized balance between active sites (Pd nanoparticles) density and capability for mass and charge transport. In addition, the protection for active moieties in the OMC frameworks contributes to its superior durability compared with Pt/C.