A Manganese-Doped\nCerium-Based Metal–Organic\nFramework as a Radical Scavenger for Proton Exchange Membrane Fuel\nCells with Superior Stability

Reducing gas permeation through proton exchange membranes\nand eliminating\nfree radicals are crucial for mitigating the degradation of proton\nexchange membranes. Here, a series of Mn-doped Ce metal–organic\nframework (MOF) materials are designed and prepared. Prepared Ce<sub>2</sub>Mn-NH<sub>2</sub>BDC can catalyze the decomposition of hydrogen\noxidation and alleviate the damage caused by free radicals. Ce<sub>2</sub>Mn-NH<sub>2</sub>BDC has a special pore structure, a high\nspecific surface area, and abundant functional groups, as well as\nthe ability to be fixed in proton exchange membranes. The fabricated\nCe<sub>2</sub>Mn-NH<sub>2</sub>BDC@PFSA membranes have excellent gas\nbarrier properties and structural stability as well as an excellent\nproton conductivity, a high fuel cell performance, and low ohmic impedance.\nThe proton conductivity can reach up to 137 mS cm<sup>–1</sup>, and the cell performance can reach 0.664 V at 2.0 A cm<sup>–2</sup>. In addition, the prepared composite membrane exhibits low weight\nloss and high water stability in the ex situ durability test, and\nit has excellent stability in the open circuit voltage (OCV) holding\ntest; its decay rate is only 33.3 μ V h<sup>–1</sup>,\nwhich is lower than those of Ce-NH<sub>2</sub>BDC@PFSA and the Nafion\n211 membrane. This work provides a promising reference value for the\npreparation of highly stable proton exchange membranes.