Development of in-situ transmission electron microscopy techniques for electrochemistry

Development of in-situ transmission electron microscopy techniques for electrochemistry

by Jonas Lindner
Doctoral thesis
Date of Examination:2024-12-16
Date of issue:2025-02-18
Advisor:Prof. Dr. Christian Jooß
Referee:Prof. Dr. Christian Jooß
Referee:Prof. Dr. Michael Seibt
Persistent Address: http://dx.doi.org/10.53846/goediss-11099

 

 

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Abstract

English

In this doctoral thesis, two newly developed in-situ transmission electron microscopy (TEM) methods are introduced, and their applications are demonstrated. The first one allows the insitu characterization and analysis of ionic-currents in the gas ambient under influence of the electron beam. This way, the creation of a diluted plasma state could be verified for noble gases as argon and helium. The plasma parameters were determined, and consequences for open cell water experiments of two electrode experiments discussed. The second developed method is the improvement of the phase shifting electron holography (PS-EH) reconstruction by the introduction of an advanced drift correction scheme. In contrast to the conventional reconstruction process in the Fourier-domain, no spatial resolution limiting aperture has to be used. Combined with the drift correction, this increases the possible spatial resolution of the reconstructed waves up to the information limit of the microscope. A spatial resolution of 1 Å is demonstrated on a platinum single crystal in the [110]-zone axis. The findings and the improved PS-EH reconstruction method are used to analyze the interface between water and the surface of a single crystal platinum (111)-surface in an electrified two electrode in-situ experiment in 50 µbar water vapor. The projected potential distribution of the platinum-water interface is resolved, compared with high vacuum measurements, and analyzed. From further analysis a dynamic platinum ad-atom layer with a coverage of 1/8 is found between the condensed water and the 1 nm thick specimen edge. Indications of an preferential orientation of the water molecules at 300 K in the first 5 Å–7 Å from the surface are found in the potential distribution. The influence of an applied external voltage is measured and studied. The results are compared to a holography signal prediction derived by the multi-slice processing of ab-initio molecular dynamics simulations from collaboration partners. Based on this comparison, a model of the experimental platinum-water surface is proposed and discussed.
Keywords: Electrochemistry; Transmission electron microscopy; Phase shifting electron holography; Metal water interface; Atomic scale catalysis
Schlagwörter: Electrochemistry; Transmission electron microscopy; Metal water interface; Atomic scale catalysis; Phase shifting electron holography