Synergistic Utilization of a CeO₂-Anchored Bifunctionalized Metal–Organic Framework in a Polymer Nanocomposite toward Achieving High Power Density and Durability of PEMFC

Abstract

The free radicals produced during the long-term operation of fuel cells can accelerate the chemical degradation of the proton exchange membrane (PEM). In the present work, the widely used free radical scavenger CeO 2 was anchored on aminofunctionalized metal−organic frameworks, and flexible alkyl sulfonic acid side chains were tethered onto the surface of inorganic nanoparticles. The prepared CeO 2 -anchored bifunctionalized metal−organic framework (CeO 2 -MNCS) was used as a promising synergistic filler to modify the Nafion matrix for addressing the detrimental effect of pristine CeO 2 on the performance and durability of PEMs, including decreased proton conductivity and the migration problem of CeO 2 . The obtained hybrid membranes exhibited a high proton conductivity up to 0.239 S cm −1 , enabling them to achieve a high power density of 591.47 mW cm −2 in a H 2 /air PEMFC single cell, almost 1.59 times higher than that of recast Nafion. After 115 h of acceleration testing, the OCV decay ratio of the hybrid membrane was decreased to 0.54 mV h −1 , which was significantly lower than that of recast Nafion (2.18 mV h −1 ). The hybrid membrane still maintained high power density, low hydrogen crossover, and unabated catalytic activity of the catalyst layer after the durability test. This study provides an effective one-stone-two-birds strategy to develop highly durable PEMs by immobilizing CeO 2 without sacrificing proton conductivity, allowing for the realization of improvement on the performance and sustained durability of PEMFC simultaneously.

Phosphate-grafted polyethyleneimine-induced multifunctional cerium oxide as an antioxidant for simultaneously enhancing the proton conductivity and durability of proton exchange membranes

“…[22] Similarly, Duan et al prepared a bifunctionalized metal-organic framework (CeO 2 -MNCS) by a two-step method in which CeO 2 was rst immobilized on an amino-functionalized metal-organic framework, and then the alkyl sulfonic acid side chains were subsequently attached on the surface of inorganic nanoparticles. [23] The Na on-based hybrid membranes produced with this ller achieved a proton conductivity of 0.239 S cm − 1 and an OCV decay rate of 0.54 mV h − 1 after 115 hours of ADT.…”

Metal–organic framework for high-performance catalyst layers in proton-exchange membrane fuel cells

“…Despite the 30% RH condition, the mof-MEA exhibited 185 mV h −1 of irreversible decay rate (DV irrev ), which is a comparable value to other long-term tests at 100% RH (Table S3, ESI †). [46][47][48][49][50][51][52][53][54][55][56][57][58] The DV irrev can be caused by membrane damage, loss of ionomer and catalyst, and structural change of CL. 59 Meanwhile, the MEA showed similar reversible voltage drop (DV rev ) during the consecutive start-up/ shut-down procedures: the DV rev values were 0.45, 0.37, and 0.49 V, for 2 nd , 3 rd , and 4 th step, respectively, exhibiting high reversibility.…”

MoS2/graphene dispersed 2‐acrylamide‐2‐methyl propane sulfonic acid grafted polyarylene ether of di‐phenylenedi‐acetal high temperature‐proton exchange membrane fuel cell application

“…Yuting Duan et al synthesized CeO 2 ‐anchored bifunctionalized MOF (CeO 2 ‐MNCS), and was utilized as an expectant synergistic filler to PEM, the CeO 2 /MOF dopped membranes showed a lower PCdue to the restricted movement of CeO 2 . The gained hybrid membranes showed a highest PC up to 2.39 × 10 −1 S/cm, allowing them to complete a highest current density of 591.47 mW cm −2 in a H 2 /O 2 PEMFC single cell, almost 1.59 times superior that of Nafion 38 …”