Catalysis is crucial for efficient chemical and energy transformations. Understanding catalysis at a molecular or even an atomic scale is the key step for designing a catalyst with high activity and selectivity. In situ/operando studies of a catalyst under a reaction condition and during catalysis allow for establishing a correlation between observed catalytic performance and its corresponding authentic surface of the catalyst during catalysis. Advances in tracking surface of catalysts with electron-based surface analytical techniques under a working condition or a semi-working condition was made. Ambient pressure X-ray photoelectron spectroscopy allows for tracking surface of a catalyst at high temperature in a gas phase with certain pressure and even a liquid phase. It has been used in examining surface of thermal catalysis and electrocatalysis in the last decade. I will describe instrumentation of lab-based AP-XPS and application of AP-XPS to study catalyst surfaces in gas phase of one reactant or mixture of all reactants of a catalytic reaction. Instrumentation of reaction cell design for simulating the fixed-bed flow reactor will be described. Data analysis and interpretation in terms of the difference between vacuum XPS and AP-XPS will be discussed. The applications of AP-XPS to catalysis can be categorized into in situ/operando of model catalysts, metal nanoparticle catalysts, and oxide nanoparticle catalysts. I will exemplify the applications of lab-based AP-XPS to studies of different types of catalysts under reaction conditions and during catalysis. In addition, I will discuss the existing challenges in applying this near-ambient pressure surface analytical technique to studies of catalysts under working conditions.

Application of ambient pressure x-ray photoelectron spectroscopy to studies of catalytic materials

254th National Meeting (2017)

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