Komma Miriam, Freiberg Anna T S, Abbas Dunia, Arslan Funda, Milosevic Maja, Cherevko Serhiy, Thiele Simon, Böhm Thomas
Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Cauerstr.1, 91058 Erlangen, Germany.
Department of Chemical and Biological Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr.1, 91058 Erlangen, Germany.
ACS Appl Mater Interfaces. 2024 Apr 27;16(18):23220-32. doi: 10.1021/acsami.4c01254.
Gas crossover is critical in proton exchange membrane (PEM)-based electrochemical systems. Recently, single-layer graphene (SLG) has gained great research interest due to its outstanding properties as a barrier layer for small molecules like hydrogen. However, the applicability of SLG as a gas-blocking interlayer in PEMs has yet to be fully understood. In this work, two different approaches for transferring SLG from a copper or a polymeric substrate onto PEMs are compared regarding their application in low-temperature PEM fuel cells. The SLG is sandwiched between two Nafion XL membranes to form a stable composite membrane. The successful transfer is confirmed by Raman spectroscopy and in ex situ hydrogen permeation experiments in the dry state, where a reduction of 50% upon SLG incorporation is achieved. The SLG composite membranes are characterized by their performance and hydrogen-blocking ability in a fuel cell setup at typical operating conditions of 80 °C and with fully humidified gases. The performance of the fuel cell incorporating an SLG composite membrane is equal to that of the reference cell when avoiding the direct etching process from a copper substrate, as remnants from copper etching deteriorate the performance of the fuel cell. For both transfer processes, the hydrogen crossover reduction of SLG composite membranes is only 15-19% (1.5 bar) in the operating fuel cell. Further, hydrogen pumping experiments suggest that the barrier function of SLG impairs the water transport through the membrane, which may affect water management in electrochemical applications. In summary, this work shows the successful transfer of SLG into a PEM and confirms the effective hydrogen-blocking capability of the SLG interlayer. However, the hydrogen-blocking ability is significantly reduced when running the cell at the typical humidified operating conditions of PEM fuel cells, which follows from a combination of reversible interlayer alteration upon humidification and irreversible defect formation upon PEM fuel cell operation.
在基于质子交换膜（PEM）的电化学系统中，气体渗透是至关重要的。近来，单层石墨烯（SLG）因其作为氢气等小分子阻挡层的卓越性能而备受研究关注。然而，SLG作为PEMs中气体阻隔中间层的适用性尚未得到充分理解。在这项工作中，比较了将SLG从铜或聚合物基底转移到PEMs上的两种不同方法在低温PEM燃料电池中的应用。SLG夹在两个Nafion XL膜之间形成稳定的复合膜。通过拉曼光谱和干燥状态下的非原位氢渗透实验证实了成功转移，在掺入SLG后氢渗透率降低了50%。SLG复合膜在80°C典型操作条件和气体完全加湿的燃料电池装置中，通过其性能和氢阻隔能力进行表征。当避免铜基底的直接蚀刻过程时，包含SLG复合膜的燃料电池性能与参比电池相当，因为铜蚀刻的残余物会降低燃料电池的性能。对于这两种转移过程，在运行的燃料电池中，SLG复合膜的氢渗透降低仅为15 - 19%（1.5巴）。此外，氢泵浦实验表明，SLG的阻隔功能会损害水通过膜的传输，这可能会影响电化学应用中的水管理。总之，这项工作展示了SLG成功转移到PEM中，并证实了SLG中间层有效的氢阻隔能力。然而，在PEM燃料电池典型的加湿操作条件下运行电池时，氢阻隔能力会显著降低，这是由于加湿时中间层的可逆变化和PEM燃料电池运行时不可逆缺陷形成共同作用的结果。
