Spöri Camillo, Falling Lorenz J, Kroschel Matthias, Brand Cornelius, Bonakdarpour Arman, Kühl Stefanie, Berger Dirk, Gliech Manuel, Jones Travis E, Wilkinson David P, Strasser Peter
Department of Chemistry, The Electrochemical Catalysis, Energy and Materials Science Laboratory, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany.
Fritz-Haber-Institut der Max-Planck Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
ACS Appl Mater Interfaces. 2021 Jan 27;13(3):3748-3761. doi: 10.1021/acsami.0c12609. Epub 2021 Jan 14.
Adoption of proton exchange membrane (PEM) water electrolysis technology on a global level will demand a significant reduction of today's iridium loadings in the anode catalyst layers of PEM electrolyzers. However, new catalyst and electrode designs with reduced Ir content have been suffering from limited stability caused by (electro)chemical degradation. This has remained a serious impediment to a wider commercialization of larger-scale PEM electrolysis technology. In this combined DFT computational and experimental study, we investigate a novel family of iridium-niobium mixed metal oxide thin-film catalysts for the oxygen evolution reaction (OER), some of which exhibit greatly enhanced stability, such as minimized voltage degradation and reduced Ir dissolution with respect to the industry benchmark IrO catalyst. More specifically, we report an unusually durable IrNbO electrocatalyst with improved catalytic performance compared to an IrO benchmark catalyst prepared in-house and a commercial benchmark catalyst (Umicore Elyst Ir75 0480) at significantly reduced Ir catalyst cost. Catalyst stability was assessed by conventional and newly developed accelerated degradation tests, and the mechanistic origins were analyzed and are discussed. To achieve this, the IrNbO mixed metal oxide catalyst and its water splitting kinetics were investigated by a host of techniques such as synchrotron-based NEXAFS analysis and XPS, electrochemistry, and DFT calculations as well as STEM-EDX cross-sectional analysis. These analyses highlight a number of important structural differences to other recently reported bimetallic OER catalysts in the literature. On the methodological side, we introduce, validate, and utilize a new, nondestructive XRF-based catalyst stability monitoring technique that will benefit future catalyst development. Furthermore, the present study identifies new specific catalysts and experimental strategies for stepwise reducing the Ir demand of PEM water electrolyzers on their long way toward adoption at a larger scale.
在全球范围内采用质子交换膜（PEM）水电解技术将需要大幅降低当今PEM电解槽阳极催化剂层中的铱负载量。然而，铱含量降低的新型催化剂和电极设计一直受到（电）化学降解导致的稳定性有限的困扰。这仍然是大规模PEM电解技术更广泛商业化的严重障碍。在这项结合密度泛函理论（DFT）计算和实验的研究中，我们研究了用于析氧反应（OER）的新型铱-铌混合金属氧化物薄膜催化剂家族，其中一些表现出大大增强的稳定性，例如相对于行业基准IrO催化剂，电压降解最小化且铱溶解减少。更具体地说，我们报告了一种异常耐用的IrNbO电催化剂，与内部制备的IrO基准催化剂和商业基准催化剂（Umicore Elyst Ir75 0480）相比，其催化性能有所提高，同时铱催化剂成本显著降低。通过传统和新开发的加速降解测试评估催化剂稳定性，并分析和讨论其机理根源。为了实现这一点，通过一系列技术研究了IrNbO混合金属氧化物催化剂及其水分解动力学，如基于同步加速器的近边X射线吸收精细结构（NEXAFS）分析和X射线光电子能谱（XPS）、电化学、DFT计算以及扫描透射电子显微镜-能量色散X射线光谱（STEM-EDX）截面分析。这些分析突出了与文献中最近报道的其他双金属OER催化剂的一些重要结构差异。在方法学方面，我们引入、验证并利用了一种基于X射线荧光（XRF）的新型非破坏性催化剂稳定性监测技术，这将有利于未来的催化剂开发。此外，本研究确定了新的特定催化剂和实验策略，以便在PEM水电解槽大规模应用的漫长道路上逐步降低其对铱的需求。
