| AVS 64th International Symposium & Exhibition | |
| Scanning Probe Microscopy Focus Topic | Monday Sessions |
| Session SP+AS+NS+SS-MoM |
| Session: | New Imaging and Spectroscopy Methodologies |
| Presenter: | Evgheni Strelcov, NIST Center for Nanoscale Science and Technology / University of Maryland |
| Authors: | E. Strelcov, NIST Center for Nanoscale Science and Technology / University of Maryland A. Tselev, University of Aveiro, Portugal H.X. Guo, NIST Center for Nanoscale Science and Technology / University of Maryland A. Yulaev, NIST Center for Nanoscale Science and Technology / University of Maryland I. Vlassiouk, Oak Ridge National Laboratory N.B. Zhitenev, NIST Center for Nanoscale Science and Technology W. McGehee, NIST Center for Nanoscale Science and Technology B. Hoskins, NIST Center for Nanoscale Science and Technology J.J. McClelland, NIST Center for Nanoscale Science and Technology A. Kolmakov, NIST Center for Nanoscale Science and Technology |
| Correspondent: | Click to Email |
Solid-liquid interfaces play an instrumental role in a broad range of natural phenomena in biological, hydrological, chemical and electrochemical systems. The latter include energy conversion and storage applications, such as fuel cells, supercapacitors, electrochromic devices, and batteries, whose performance strongly depends on the state of the solid-liquid interface. Key elements of this interfacial behavior are the formation of the electrical double layer (EDL), ionic transport through it, ionic adsorption, and Faradaic processes. Thus, understanding the structure and properties of the EDL is of critical importance. Despite more than a century of research on the EDL, its molecular structure and electrode potential dependence remain the subject of frontier research. Only a handful of experimental techniques, including surface force and spectral methods, are currently available for direct probing of the EDL, but even they do not offer adequate spatial resolution.
Here, we report on direct measurement of the EDL potential in a copper (II) sulfate electrolyte with Kelvin Probe Force microscopy (KPFM). The aqueous electrolyte is placed in a multichannel array, consisting of high aspect ratio, 2 μm diameter channels, sealed at the bottom and capped with bilayer graphene at the top. The system can be imaged in vacuo with high resolution scanning electron microscopy and KPFM, correlatively. The graphene membrane acts as both an electrode and a seal that prevents the electrolyte from evaporating into the vacuum. The KPFM probe scans over the subnanometer graphene membrane of individual channels and records potential of the EDL formed at the electrified graphene-electrolyte interface. Both graphene and bottom platinum electrode can be biased to modulate the response of the system to polarization. The collected data are compared to numerical simulation of EDL formation.
ES, HG, and AY acknowledge support under the Cooperative Research Agreement between the University of Maryland and the National Institute of Standards and Technology Center for Nanoscale Science and Technology, Award 70NANB14H209, through the University of Maryland. WM and BH acknowledge support of the National Research Council Research Associateship Program.