期刊
NANO LETTERS
卷 20, 期 2, 页码 1336-1344出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.9b04823
关键词
Electrical double layer; graphene; electrolyte interface; KPFM; SEM
类别
资金
- University of Maryland [70NANB14H209]
- National Institute of Standards and Technology Center for Nanoscale Science and Technology through the University of Maryland [70NANB14H209]
- National Natural Science Foundation of China [11874105]
- Professional Research Experience Program (PREP)
- national funds through the FCT/MEC [UIDB/S0011/2020, UIDP/50011/2020]
- FEDER
The electrical double layer (EDL) governs the operation of multiple electrochemical devices, determines reaction potentials, and conditions ion transport through cellular membranes in living organisms. The few existing methods of EDL probing have low spatial resolution, usually only providing spatially averaged information. On the other hand, traditional Kelvin probe force microscopy (KPFM) is capable of mapping potential with nanoscale lateral resolution but cannot be used in electrolytes with concentrations higher than several mmol/L. Here, we resolve this experimental impediment by combining KPFM with graphenecapped electrolytic cells to quantitatively measure the potential drop across the EDL in aqueous electrolytes of decimolar and molar concentrations with a high lateral resolution. The surface potential of graphene in contact with deionized water and 0.1 mol/L solutions of CuSO4 and MgSO4 as a function of counter electrode voltage is reported. The measurements are supported by numerical modeling to reveal the role of the graphene membrane in potential screening and to determine the EDL potential drop. The proposed approach proves to be especially useful for imaging spatially inhomogeneous systems, such as nanoparticles submerged in an electrolyte solution. It could be suitable for in operando and in vivo measurements of the potential drop in the EDL on the surfaces of nanocatalysts and biological cells in equilibrium with liquid solutions.
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