TY - JOUR
T1 - Three-Dimensional Molecular Mapping of Ionic Liquids at Electrified Interfaces
AU - Zhou, Shan
AU - Panse, Kaustubh S.
AU - Motevaselian, Mohammad Hossein
AU - Aluru, Narayana R.
AU - Zhang, Yingjie
N1 - Funding Information:
Acknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund for support of this research (S.Z., K.S.P., and Y.Z.). The experiments were performed in part in the Carl R. Woese Institute for Genomic Biology and in the Materials Research Laboratory at the University of Illinois. S.Z., K.S.P., and Y.Z. acknowledge the use of facilities and instrumentation supported by the National Science Foundation (NSF) through the University of Illinois Materials Research Science and Engineering Center (DMR-1720633). M.H.M. and N.R.A. were supported by the NSF under Grants 1545907, 1708852, 1720633, and 1921578. The computing power is provided by the Extreme Science and Engineering Discovery Environment (XSEDE) granted by the NSF with Grant No. OCI-1053575 and Blue Waters supercomputing center, awarded by the state of Illinois and the NSF, OCI-0725070, ACI-1238993.
Publisher Copyright:
©
PY - 2020/12/22
Y1 - 2020/12/22
N2 - Electric double layers (EDLs), occurring ubiquitously at solid-liquid interfaces, are critical for electrochemical energy conversion and storage processes such as capacitive charging and redox reactions. However, to date the molecular-scale structure of EDLs remains elusive. Here we report an advanced technique, electrochemical three-dimensional atomic force microscopy (EC-3D-AFM), and use it to directly image the molecular-scale EDL structure of an ionic liquid under different electrode potentials. We observe not only multiple discrete ionic layers in the EDL on a graphite electrode but also a quasi-periodic molecular density distribution within each layer. Furthermore, we find pronounced 3D reconfiguration of the EDL at different voltages, especially in the first layer. Combining the experimental results with molecular dynamics simulations, we find potential-dependent molecular redistribution and reorientation in the innermost EDL layer, both of which are critical to EDL capacitive charging. We expect this mechanistic understanding to have profound impacts on the rational design of electrode-electrolyte interfaces for energy conversion and storage.
AB - Electric double layers (EDLs), occurring ubiquitously at solid-liquid interfaces, are critical for electrochemical energy conversion and storage processes such as capacitive charging and redox reactions. However, to date the molecular-scale structure of EDLs remains elusive. Here we report an advanced technique, electrochemical three-dimensional atomic force microscopy (EC-3D-AFM), and use it to directly image the molecular-scale EDL structure of an ionic liquid under different electrode potentials. We observe not only multiple discrete ionic layers in the EDL on a graphite electrode but also a quasi-periodic molecular density distribution within each layer. Furthermore, we find pronounced 3D reconfiguration of the EDL at different voltages, especially in the first layer. Combining the experimental results with molecular dynamics simulations, we find potential-dependent molecular redistribution and reorientation in the innermost EDL layer, both of which are critical to EDL capacitive charging. We expect this mechanistic understanding to have profound impacts on the rational design of electrode-electrolyte interfaces for energy conversion and storage.
KW - 3D-AFM
KW - electric double layer
KW - electrochemical AFM
KW - electrode-electrolyte interface
KW - ionic liquid
KW - solid-liquid interface
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U2 - 10.1021/acsnano.0c07957
DO - 10.1021/acsnano.0c07957
M3 - Article
C2 - 33227191
AN - SCOPUS:85097821501
VL - 14
SP - 17515
EP - 17523
JO - ACS Nano
JF - ACS Nano
SN - 1936-0851
IS - 12
ER -