Nitrogen-Doped Carbon Nanotubes as Platinum Catalyst Supports for Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cells

Nitrogen-doped carbon nanotubes (N-CNTs) were utilized as platinum nanoparticle support materials, with the significant effect of the nitrogen precursor solution utilized N-CNT growth elucidated. N-CNTs synthesized from a nitrogen-rich ethylenediamine (ED) precursor solution (ED-CNTs) were found to have superior catalytic activity toward the oxygen reduction reaction (ORR) compared with N-CNTs grown from a precursor solution with relatively low nitrogen content pyridine (Py-CNTs). Significant increase in the nitrogen incorporation and edge plane exposure was observed for ED-CNTs. When utilized as platinum nanoparticle supports, Pt/ED-CNTs displayed significantly enhanced electrocatalytic activity toward the ORR when compared with Pt/Py-CNTs and nitrogen free Pt/CNTs, with the increase in performance being attributed to the distinct structural and electronic enhancements resulting from heterogeneous nitrogen doping. The performance of Pt/ED-CNTs as a cathodic catalyst for proton exchange membrane fuel cell operation was found to be significantly higher than that of Pt/CNT.