Todd Brintlinger1 Nabraj Bhattarai2 1

1, U.S. Naval Research Lab, Washington, District of Columbia, United States
2, National Research Council, Washington, District of Columbia, United States

To probe the effect of electron beam irradiation in commercial electrochemical liquid cell transmission electron microscope (LCTEM) holders,[1] we use a model system of platinum electrodes and sulfuric acid to investigate how intermediate-to-low intensity electron beams affect cyclic voltammograms (CVs), and how the CVs change with time and beam current during irradiation in a flowing electrolyte. Using the largest field-of-view and small beam currents for the ‘standard’ viewing conditions in our TEM (a JEOL JEM2200FS), we see a potential shift (~ 100mV) in the entire CV when turning the beam on and off during potential cycling. For the same electrode geometry, increased electron beam currents cause increased currents in the oxidative and reductive portions of the CV, but the static potential shift remains constant. However, a larger physical separation between the reference and working electrode does change the static potential shift. Following Jiang, [2] we understand the static potential shift to arise from positive charge on both the top and bottom silicon nitride membrane. Using the measured potential shift and electrode geometry, we estimate the presence of ~10-100 aC at the top and bottom membrane. Finally, we see that ‘beam-off’ CVs can be recovered following irradiation after a brief period without irradiation, which indicates the flow of liquid through the cell allows new electrolyte to both replace the irradiated portions of electrolyte and to dissipate static charges such that the original, beam-off CV is recovered, but there is a finite time associated with this recovery which may impact the maximum speed of LCTEM experiments. We will present these results on this canonical electrochemical system and discuss the impact on LCTEM. The authors acknowledge funding from the Office of Naval Research (Naval Research Laboratory Basic Research Program). This research was performed while N.B. held a National Research Council Research Associate Award at the U.S. Naval Research Laboratory.

[1] H. Zheng, Y. S. Meng, Y. Zhu (Guest Editors) MRS Bulletin Vol. 40, Issue 1 (Jan. 2015)
[2] Nan Jiang, Micron Vol. 83, 79-92 (April 2016)