A manganese doping deficient cerium base metal organic framework as radical scavenger for highly-durable proton exchange membrane water electrolysis

Abstract

Eliminating hydrogen peroxide and free radicals from electrochemical reactions is crucial for mitigating chemical degradation and improving the durability of proton exchange membranes (PEMs). Herein, we prepare a metal–organic framework containing manganese and cerium ions that possesses oxygen vacancy defects and amino functional groups. The prepared Ce4MnBDC-NH2 acts as a catalyst for H2O2 decomposition and as a free radical scavenger, and it is incorporated into a perfluorosulfonic acid (PFSA) ionomer matrix. Featuring large pore volume, high porosity, and abundant amino groups, the Ce4MnBDC-NH2 is locked in a PEM. The obtained Ce4Mn-NH2BDC@PFSA composite membrane exhibits high dimensional stability, excellent proton conductivity and low high-frequency impedance, yielding a proton conductivity of up to 137 mS cm–1 and superior water electrolysis performance of up to 1.83 V at 3.0 A cm–2. Moreover, the obtained Ce4Mn-NH2BDC@PFSA membrane experiences lower weight loss during the Fenton reaction, a low fluoride-ion release rate, and excellent stability in high current density durability testing: its decay rate is only 5.2 μV h–1, which is lower than that of CeO2@PFSA and Nafion 117 membranes. This work provides a promising method to prepare efficient free radical scavengers for steady-state PEM water electrolysis.