Liu Chang, Wippermann Klaus, Rasinski Marcin, Suo Yanpeng, Shviro Meital, Carmo Marcelo, Lehnert Werner
Institute of Energy and Climate Research, IEK-14: Electrochemical Process Engineering, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
Faculty of Mechanical Engineering, RWTH Aachen University, 52062 Aachen, Germany.
ACS Appl Mater Interfaces. 2021 Apr 14;13(14):16182-16196. doi: 10.1021/acsami.0c20690. Epub 2021 Apr 2.
The cell performance and durability of polymer electrolyte membrane (PEM) water electrolyzers are limited by the surface passivation of titanium-based porous transport layers (PTLs). In order to ensure stable performance profiles over time, large amounts (≥1 mg·cm) of noble metals (Au, Pt, Ir) are most widely used to coat titanium-based PTLs. However, their high cost is still a major obstacle toward commercialization and widespread application. In this paper, we assess different loadings of iridium, ranging from 0.005 to 0.05 mg·cm in titanium PTLs, that consequently affect the investment costs of PEM water electrolyzers. Concerning a reduction in the precious metal costs, we found that Ir as a protective layer with a loading of 0.025 mg·cm on the PTLs would be sufficient to achieve the same cell performance as PTLs with a higher Ir loading. This Ir loading is a 40-fold reduction over the Au or Pt loading typically used for protective layers in current commercial PEM water electrolyzers. We show that the Ir protective layer here not only decreases the Ohmic resistance significantly, which is the largest part of the gain in performance, but moreover, the oxygen evolution reaction activity of the iridium layer makes it promising as a cost-effective catalyst layer. Our work also confirms that the proper construction of a multifunctional interface between a membrane and a PTL indeed plays a crucial role in guaranteeing the superior performance and efficiency of electrochemical devices.
聚合物电解质膜（PEM）水电解槽的电池性能和耐久性受到钛基金属多孔传输层（PTL）表面钝化的限制。为了确保随着时间推移性能稳定，大量（≥1 mg·cm）的贵金属（金、铂、铱）被最广泛地用于涂覆钛基PTL。然而，它们的高成本仍然是商业化和广泛应用的主要障碍。在本文中，我们评估了钛基PTL中铱的不同负载量，范围从0.005到0.05 mg·cm，这会影响PEM水电解槽的投资成本。关于降低贵金属成本，我们发现，在PTL上负载量为0.025 mg·cm的铱作为保护层，足以实现与更高铱负载量的PTL相同的电池性能。这种铱负载量比当前商业PEM水电解槽中通常用于保护层的金或铂负载量降低了40倍。我们表明，这里的铱保护层不仅显著降低了欧姆电阻，这是性能提升的最大部分，而且铱层的析氧反应活性使其有望成为一种具有成本效益的催化剂层。我们的工作还证实，在膜和PTL之间正确构建多功能界面确实在保证电化学装置的卓越性能和效率方面起着关键作用。
