Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee (UT) Space Institute, UT, Knoxville, TN 37388, USA.
Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
Sci Adv. 2016 Nov 18;2(11):e1600690. doi: 10.1126/sciadv.1600690. eCollection 2016 Nov.
Better understanding of true electrochemical reaction behaviors in electrochemical energy devices has long been desired. It has been assumed so far that the reactions occur across the entire catalyst layer (CL), which is designed and fabricated uniformly with catalysts, conductors of protons and electrons, and pathways for reactants and products. By introducing a state-of-the-art characterization system, a thin, highly tunable liquid/gas diffusion layer (LGDL), and an innovative design of electrochemical proton exchange membrane electrolyzer cells (PEMECs), the electrochemical reactions on both microspatial and microtemporal scales are revealed for the first time. Surprisingly, reactions occur only on the CL adjacent to good electrical conductors. On the basis of these findings, new CL fabrications on the novel LGDLs exhibit more than 50 times higher mass activity than conventional catalyst-coated membranes in PEMECs. This discovery presents an opportunity to enhance the multiphase interfacial effects, maximizing the use of the catalysts and significantly reducing the cost of these devices.
长期以来，人们一直希望更好地了解电化学能源设备中真实的电化学反应行为。到目前为止，人们一直假设反应发生在整个催化剂层（CL）中，该层是通过设计和制造均匀的催化剂、质子和电子导体以及反应物和产物的通道来实现的。通过引入先进的表征系统、薄且高度可调的液体/气体扩散层（LGDL）以及电化学质子交换膜电解槽（PEMEC）的创新设计，首次揭示了微观和微时尺度上的电化学反应。令人惊讶的是，反应仅发生在与良好电导体相邻的 CL 上。基于这些发现，新型 LGDL 上的新型 CL 制造工艺在 PEMEC 中的质量活性比传统的催化剂涂覆膜高出 50 多倍。这一发现为增强多相界面效应提供了机会，可以最大限度地利用催化剂，并显著降低这些设备的成本。
