Fast in situ - spectroscopy of electrocatalytic fuel cell reactions - Methodic development and mechanistic studies

在这个项目中，我们建议开发新的方法，在连续的反应和连续的电解质流动条件下，这是特别相关的电催化燃料电池反应在现实的反应条件下的调查原位红外光谱研究。这些方法应允许i）在微结构模型系统上以约50 µs的（系统）时间分辨率对吸附物质进行极快的原位测量，以及ii）在燃料电池相关条件下对负载型催化剂进行组合原位IR、原位质谱和电化学测量（见上文）。前者涉及设计和建立一个特殊的微流动池，微电极和步进扫描红外检测通过红外显微镜，将允许时间分辨原位光谱研究与前所未有的时间分辨率。这是特别有价值的非固定条件下的研究，产生的反应过程的初始阶段的机械信息。后者基于衰减反射（ATR）几何结构中的FTIR测量，并且需要开发在导电、电化学惰性和足够IR透明的基底上具有负载催化剂薄膜的新型电极，这将使我们能够同时获得关于吸附和挥发性的电化学数据和原位光谱信息，在反应条件下解吸实际负载型催化剂上的物质。由于它们的时间分辨率和材料要求不同，这些方法彼此具有很强的互补性。这些技术对于在低温聚合物电解质燃料电池（PEFC）中的有机分子的电氧化的原位研究是特别有趣的，其中由于复杂的反应方案，机械理解关键地取决于在反应条件下挥发性解吸物种和吸附物种的知识，并且其中，出于相同的原因，非稳态测量可以显著地增加机械理解。因此，作为概念的证明，我们将证明这些技术的可行性和贡献的理解电催化燃料电池反应的动力学和机械研究的有机分子，特别是低醇的电氧化。

In this project we propose to develop new methods for in-situ IR spectroscopic studies under continuous reaction and continuous electrolyte flow conditions, which are of particular relevance for the investigation of electrocatalytic fuel cell reactions under realistic reaction conditions. These methods shall allow i) extremely fast in-situ measurements of adsorbed species with a (system) time resolution of about 50 µs on microstructured model systems, and ii) combined insitu IR, in-situ mass spectrometric and electrochemical measurements on supported catalysts under fuel cell relevant conditions (see above). The former, which involves the design and build-up of a special micro-flow cell with a microelectrode and step-scan IR detection via an IR microscope, will allow time-resolved in-situ spectroscopic studies with an unprecedented time resolution. This is particularly valuable for studies under non-stationary conditions, which yield mechanistic information on the initial stages of the reaction process. The latter, which is based on FTIR measurements in an Attenuated Reflection (ATR) geometry and which requires the development of novel electrodes with a thin film of supported catalyst on a conducting, electrochemically inert, and sufficiently IR transparent substrate, will enable us to simultaneously acquire electrochemical data and in-situ spectroscopic information on the adsorbed and volatile, desorbing species on realistic supported catalysts under reaction conditions. Because of their different time resolution and material requirements these methods are highly complementary to each other. These techniques are particularly interesting for in-situ studies on the electrooxidation of organic molecules in low temperature polymer electrolyte fuel cells (PEFCs), where because of the complex reaction scheme a mechanistic understanding depends crucially on the knowledge of both volatile desorbing species and adsorbed species under reaction conditions, and where, from the same reason, instationary measurements can add significantly to the mechanistic understanding. As a proof of concept we will therefore demonstrate the feasibility and contribution of these techniques for the understanding of electrocatalytic fuel cell reactions in kinetic and mechanistic studies on the electrooxidation of organic molecules, in particular low alcohols.