Scanning Probe Microscope

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In situ scanning probe microscopy methods, such as scanning tunneling (STM) and atomic force microscopy (AFM), are central tools for clarifying the atomic structure of electrochemical interfaces and processes occurring at these interfaces. The Magnussen group belongs to the international leading groups in this area and, in particular, established in situ high-speed scanning tunneling microscopy (Video-STM) as a unique method for quantitative studies of dynamic processes at electrode surfaces. Aim of this proposal is to construct a new microscope that allows Video-STM as well as conventional STM/AFM measurements in electrochemical environment and combines these microscopic characterization methods with a quantitative analysis of the products of electrode reactions by gas (GC) and liquid chromatography (HPLC). This novel combination will allow to correlate the reactivity and selectivity of electrochemical processes directly with the atomic-scale electrode structure, enabling the determination of structure-property relationships for electrocatalytic reactions at well-defined model catalysts. The instrument will be an essential tool for a multitude of ongoing and planned research projects of the group, such as studies of electrochemical CO2 reduction, diffusion and interaction of adsorbates at electrode surfaces, structure of functional self-assembled organic layers, and the degradation of catalysts for electrochemical oxygen evolution and reduction. The planned microscope will be a worldwide unique instrument. It will be built based on commercial available components but requires extensive in-house development, especially of the microscope head and the Video-STM module. The required specifications are i) measurements under electrochemical control, ii) high-quality atomically resolved STM images at recording rates of 20 images/s, iii) the possibility for continuous electrolyte exchange, iv) operation under controlled atmosphere (Ar, CO2), v) separate microscope head for in situ AFM studies, and vi) direct quantitative analytics of the gaseous and liquid products produced by electrode reactions in the STM/AFM cell. For the latter, a combination of online-GC, injection-GC, and HPLC will be used, with a configuration that is derived from the concrete measurement requirements of an ongoing project on electrochemical CO2 reduction. In total, the instrument will open up novel possibilities for in situ and operando studies, which in particular will provide new insights into processes in electrochemical energy technology.