Enhancing Oxygen Transport in Proton Exchange Membrane Fuel Cell Through Nanoconfined Triple Phase Interface Engineering

Abstract In proton exchange membrane fuel cells (PEMFCs), ionomer aggregation on Pt/C catalysts leads to increased oxygen transport resistance of conventional catalyst layers. This behavior significantly influences oxygen transport in the microenvironment at the triple‐phase interface of Pt/C catalysts. To address this challenge, triazine‐based covalent organic frameworks (COFs) were incorporated into the cathode catalyst layer, so that their well‐defined pore structure and proton eligible triazine sites interact with terminal sulfonate groups of the Nafion ionomer. This interaction regulates the triple‐phase microenvironment, enhances Pt utilization, and establishes directed oxygen‐enriched transport channels. Under low‐platinum loading conditions (−0.05 mg Pt cm −2 ) in a H 2 ─O 2 PEMFC, the COF‐modified system achieved a peak power density of 1.55 W cm −2 , 1.3 times of conventional PEMFCs, with a 38% reduction in local oxygen transport resistance. This work presents a new design principle for high‐performance low‐platinum PEMFCs, as a new approach to further advance their commercialization.