Ultra-High Proton Conductivity iHOF Based on Guanidinium Arylphosphonate for Proton Exchange Membrane Fuel Cells

The development of high-performance proton exchange membrane fuel cells (PEMFCs) is crucial yet challenging. Enrichment of proton transport pathways by doping ionic hydrogen-bonded organic frameworks (iHOFs) in Nafion matrix is important for further development of high-performance PEMFCs. In this work, an iHOF material (iHOF-9) based on arylphosphonate anions and guanidinium cations with the three-dimensional (3D) hydrogen-bonded network was synthesized, which exhibits an ultrahigh proton conductivity of 4.38 × 10–2 S·cm–1 at 90 °C and 98% RH. In addition, by mixing iHOF into Nafion matrix, we have fabricated the high-performance hybrid membranes, and the maximum proton conductivity value can achieve 6.61 × 10–2 S·cm–1 for 9%-iHOF-9/Nafion membrane at 90 °C and 98% RH. iHOF-9/Nafion membranes were used to fabricate the proton exchange membranes for application in H2/O2 fuel cells. The maximum power density of 9%-iHOF-9/Nafion reached 1092.07 mW·cm–2 after stabilization for 10 h at 80 °C and 100% RH, which is a 33.99% improvement compared to the recast Nafion membrane. This work doped ultrahigh conductivity iHOF into the Nafion matrix as an emerging proton exchange membrane material, injecting new possibilities for the development of new energy sources.