| AVS 65th International Symposium & Exhibition | |
| In-situ Microscopy, Spectroscopy, and Microfluidics Focus Topic | Monday Sessions |
| Session MM+AS+NS+PC+SS-MoA |
| Session: | X-ray and Electron Spectromicroscopy in Liquids and Gases & Flash Networking Session |
| Presenter: | Daan Hein Alsem, Hummingbird Scientific |
| Authors: | D.H. Alsem, Hummingbird Scientific K. Karki, Hummingbird Scientific J.T. Mefford, Stanford University W.C. Chueh, Stanford University N.J. Salmon, Hummingbird Scientific |
| Correspondent: | Click to Email |
Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and synchrotron X-ray microscopy (XRM) are powerful characterization tools and are routinely used to study a wide range of material-systems at the nanoscale. This has generated strong interests in acquiring more reliable quantitative in-situ and operando measurements in realistic reaction environments, as is possible with liquid environmental cells. This approach has already started to produce new insights on the dynamics and structural changes during electrochemical processes as lithium ion insertion/extraction, dendrite formation, metal nucleation and corrosion. However, practical aspects of replicating representative electrochemical data reminiscent of bulk behavior are still a challenge in these systems.
Here, we will discuss practical aspects of conducting operando liquid cell microscopy experiments relating to the typical geometry of these liquid-cell microscopy systems as well as artifacts coming from the microscope during operando experiments. We will also present a TEM/SEM/XRM microscopy platform that enables true electroanalytical measurements mimicking bulk behavior of the material system.
The example study shown here is performed using electrochemical cells, which consist of two microfabricated chips sandwiched with transparent SiNx membranes for encapsulating liquid and viewing in the microscope. A newly developed hardware system and specially optimized electrochemistry chips with a custom configuration for working electrode (WE), counter electrode (CE) and reference electrode (RE) allows quantitative measurements of electrochemical processes with details resembling the complete cycle of the bulk. As illustrations, we present cyclic voltammetry (CV) studies of some model compounds such as 01.M CuSO4 and 20 mM K3Fe(CN)6/20 mM K4Fe(CN)6 in 0.1M KCl solutions. In the former case, the copper deposition and stripping occurs at the working electrode at distinct redox peaks in liquid cell and the result mimics the bulk electrochemical cells with large electrode areas and larger volume of electrolyte solution. This work highlights the fact that with suitable hardware systems and with knowledge and correction of microscope-induced artifacts, bulk behavior of the electrochemical processes can be both observed and measured quantitatively.