Highly Dispersed Nonprecious Metal Catalyst for Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cells

This study reports a high-performing nonprecious metal catalyst for the oxygen reduction reaction that is composed of highly dispersed Fe centered active sites on bamboolike carbon nanotubes. NH₂-MIL-88B is used as the iron source and ZIF-8 as the carbon source. The precursors are uniformly mixed by ball milling, which destroys their crystal structures. A bamboolike carbon nanotube network results from the pyrolysis of the mixed precursors. The morphology is controlled by the proportion of the precursors and the pyrolysis temperature. The catalyst shows excellent oxygen reduction activity in both half-cell and full-cell tests. The onset potential and half-wave potential are 0.96 and 0.78 V vs RHE, respectively. In the fuel cell test, the current density reaches 0.85 A cm^-2 at 0.7 V and 1.24 A cm^-2 at 0.6 V (iR-corrected). The novel synthesis approach of the highly dispersed catalyst provides new strategy in the design of high effective nonprecious metal catalysts for fuel cell.