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

Abstract

Non-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.

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