Cobalt Oxide Model Catalysis Across the Materials and Pressure Gap (COMCAT)

钴氧化物是一种新型的、高活性的多相催化剂，可用于未来能源和环境技术的关键工艺。这包括例如低温CO氧化、相关的PROX反应（过量H2中CO的优先氧化）、VOC（挥发性有机化合物）的完全氧化和烃含氧化合物的重整用于氢气生产。最重要的是，基于氧化钴的催化剂具有替代或减少对关键材料（贵金属和稀土氧化物）的需求的独特潜力。尽管有这些突出的前景，令人惊讶的钴氧化物表面化学的起源至今仍是一个谜。活性对表面结构的极端依赖性和金属（例如Pd）和氧化物（例如CeO 2）改性剂增强稳定性和活性的机制都没有得到真正的理解。该联合项目的目的是在分子水平上了解钴氧化物材料的催化活性。为了实现这一目标，项目合作伙伴汇集了互补的专业知识，以实现最先进的催化模型（表面科学）方法：（A）复杂模型催化剂上反应位点的原子水平结构表征，（B）超高真空条件下催化反应的机理和微观动力学研究，和（C）通过原位光谱学将该知识转移到实际的反应条件直至实际的环境压力条件。我们将利用一个项目合作伙伴在制备有序氧化钴薄膜方面的领先专业知识，提供对独特的体结构和表面结构库的访问。我们将探测这些表面结构上的吸附和反应，在原子尺度上表征其几何和电子性质的相关缺陷，并随后通过金属（Pd）和氧化物（CeO 2）助催化剂修改这些结构。在本计画中，我们将以低温CO氧化及PROX为主要研究方向，但对氧化及重整反应进行初步探索。同时，我们将首次跨越钴氧化物催化剂的材料差距和压力差距，并最终通过从超高真空到实际反应条件的原位光谱将所获得的知识与工业级粉末催化剂联系起来。该项目的跨学科方法将使我们能够以前所未有的细节水平确定催化过程的结构-功能关系，并将指导复杂多功能钴氧化物催化剂未来发展的合理策略。

Cobalt oxide has recently turned out to be a novel, highly active heterogeneous catalyst for key processes in future energy and environmental technology. This includes e.g. low-temperature CO oxidation, the related PROX reaction (preferential oxidation of CO in excess H2), the total oxidation of VOCs (volatile organic compounds), and the reforming of hydrocarbon oxygenates for hydrogen production. Most importantly, cobaltoxide- based catalysts hold a unique potential for replacing or reducing the demand for critical materials (noble metals and rare earth oxides). Despite these outstanding prospects, the origin of the surprising cobalt oxide surface chemistry has remained a mystery up to date. Neither the extreme dependence of activity on surface structure nor the mechanisms by which metal (e.g. Pd) and oxide (e.g. CeO2) modifiers enhance stability and activity are truly understood. The aim of this joint project is to acquire an understanding of the catalytic activity of cobalt oxide materials at the molecular level. Towards this aim the project partners bring together the complementary expertise for a state-of-the-art model catalysis (surface science) approach: (A) the atomic-level structural characterization of reactive sites on complex model catalysts, (B) mechanistic and microkinetic studies of catalytic reactions under UHV conditions, and (C) transfer of this knowledge to realistic reaction conditions by in-situ spectroscopy up to realistic ambient pressure conditions. We will take advantage of the leading expertise of one project partner in preparation of ordered cobalt oxide films, providing access to a unique library of bulk and surfaces structures. We will probe adsorption and reaction on these surface structures, characterize relevant defects at the atomic scale with respect to their geometric and electronic properties, and subsequently modify these structures by metal (Pd) and oxide (CeO2) cocatalysts. In this project, we will mainly focus on low-temperature CO-oxidation and PROX, but perform first explorative work towards oxidation and reforming reactions. Simultaneously, we will cross the materials gap and the pressure gap for cobalt oxide catalysts for the first time and, finally, link the obtained knowledge to industrial-grade powder catalysts by in-situ spectroscopy from UHV to realistic reaction conditions. The interdisciplinary approach of this project will allow us to identify structure-functionality relationships of catalytic processes at an unprecedented level of detail and will guide rational strategies towards future development of complex multifunctional cobalt oxide catalysts.