A Manganese-Doped Cerium-Based Metal–Organic Framework as a Radical Scavenger for Proton Exchange Membrane Fuel Cells with Superior Stability

Reducing gas permeation through proton exchange membranes and eliminating free radicals are crucial for mitigating the degradation of proton exchange membranes. Here, a series of Mn-doped Ce metal–organic framework (MOF) materials are designed and prepared. Prepared Ce2Mn-NH2BDC can catalyze the decomposition of hydrogen oxidation and alleviate the damage caused by free radicals. Ce2Mn-NH2BDC has a special pore structure, a high specific surface area, and abundant functional groups, as well as the ability to be fixed in proton exchange membranes. The fabricated Ce2Mn-NH2BDC@PFSA membranes have excellent gas barrier properties and structural stability as well as an excellent proton conductivity, a high fuel cell performance, and low ohmic impedance. The proton conductivity can reach up to 137 mS cm–1, and the cell performance can reach 0.664 V at 2.0 A cm–2. In addition, the prepared composite membrane exhibits low weight loss and high water stability in the ex situ durability test, and it has excellent stability in the open circuit voltage (OCV) holding test; its decay rate is only 33.3 μ V h–1, which is lower than those of Ce-NH2BDC@PFSA and the Nafion 211 membrane. This work provides a promising reference value for the preparation of highly stable proton exchange membranes.