Boosting the Oxygen Reduction Performance of Fe–N–C Catalyst Using Zeolite as an Oxygen Reservoir

Abstract

AbstractNon-precious metal electrocatalysts (such as Fe–N–C materials) for the oxygen (O2) reduction reaction demand a high catalyst loading in fuel cell devices to achieve workable performance. However, the extremely low solubility of O2 in water creates severe mass transport resistance in the thick catalyst layer of Fe–N–C catalysts. Here, we introduce silicalite-1 nanocrystals with hydrophobic cavities as sustainable O2 reservoirs to overcome the mass transport issue of Fe–N–C catalysts. The extra O2 supply to the adjacent catalysts significantly alleviated the negative effects of the severe mass transport resistance. The hybrid catalyst (Fe–N–C@silicalite-1) achieved a higher limiting current density than Fe–N–C in the half-cell test. In the H2–O2 and H2–air proton exchange membrane fuel cells, Fe–N–C@silicalite-1 exhibited a 16.3% and 20.2% increase in peak power density compared with Fe–N–C, respectively. The O2-concentrating additive provides an effective approach for improving the mass transport imposed by the low solubility of O2 in water.