Overcoming the Conductance versus Crossover Trade-off in State-of-the-Art Proton Exchange Fuel-Cell Membranes by Incorporating Atomically Thin Chemical Vapor Deposition Graphene

Nicole K Moehring; Abdul Bashith Mansoor Basha; Pavan Chaturvedi; Thomas Knight; Xiaozong Fan; Peter N Pintauro; Michael S H Boutilier; Kunal Karan; Piran R Kidambi

doi:10.1021/acs.nanolett.4c05725

Overcoming the Conductance versus Crossover Trade-off in State-of-the-Art Proton Exchange Fuel-Cell Membranes by Incorporating Atomically Thin Chemical Vapor Deposition Graphene

Nano Lett. 2025 Jan 22;25(3):1165-1176. doi: 10.1021/acs.nanolett.4c05725. Epub 2025 Jan 13.

Authors

Nicole K Moehring^{1

2

3}, Abdul Bashith Mansoor Basha⁴, Pavan Chaturvedi^{2

3}, Thomas Knight⁵, Xiaozong Fan², Peter N Pintauro², Michael S H Boutilier⁶, Kunal Karan⁴, Piran R Kidambi^{1

2

3

7

8}

Affiliations

¹ Interdisciplinary Graduate Program in Materials Science, Vanderbilt University, Nashville, Tennessee 37235, United States.
² Chemical and Biomolecular Engineering Department, Vanderbilt University, Nashville, Tennessee 37212, United States.
³ Vanderbilt Institute of Nanoscale Science and Engineering, Nashville, Tennessee 37212, United States.
⁴ Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada.
⁵ Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States.
⁶ Department of Chemical and Biochemical Engineering, Western University, London, Ontario N6A 5B9, Canada.
⁷ Mechanical Engineering Department, Vanderbilt University, Nashville, Tennessee 37212, United States.
⁸ Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712-1591, United States.

Abstract

Permeance-selectivity trade-offs are inherent to polymeric membranes. In fuel cells, thinner proton exchange membranes (PEMs) could enable higher proton conductance and increased power density with lower area-specific resistance (ASR), smaller ohmic losses, and lower ionomer cost. However, reducing thickness is accompanied by an increase in undesired species crossover harming performance and long-term efficiency. Here, we show that incorporating atomically thin monolayer graphene synthesized via scalable chemical vapor deposition (CVD) and tunable defect density into PEMs (Nafion, ∼5-25 μm thick) can allow for reduced H₂ crossover (∼34-78% of Nafion of a similar thickness) while maintaining adequate areal proton conductance for applications (>4 S cm^-2). In contrast to most prior work using >50 μm symmetric Nafion sandwich structures, we elucidate the interplay of graphene defect density and Nafion proton transport resistance on the performance of Nafion|graphene composite membranes and find high-quality low-defect density CVD graphene (G) supported on Nafion 211 (∼25 μm); i.e., N211|G has a high areal proton conductance (∼6.1 S cm^-2) and the lowest H₂ crossover (∼0.7 mA cm^-2). Fully functional centimeter-scale N211|G fuel-cell membranes demonstrate performance comparable to that of state-of-the-art Nafion N211 at room temperature as well as standard operating conditions (∼80 °C, ∼150-250 kPa-abs) with H₂/air (power density ∼0.57-0.63 W cm^-2) and H₂/O₂ feed (power density ∼1.4-1.62 W cm^-2) and markedly reduced H₂ crossover (∼53-57%).

Keywords: Nafion; chemical vapor deposition (CVD); conductance vs crossover trade-off; crossover reduction; fuel cell; graphene; permeance vs selectivity; proton exchange membrane (PEM).