resumo
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.
palavras-chave
FIELD-EFFECT TRANSISTORS; ELECTRIC DOUBLE-LAYERS; FORCE MICROSCOPY; IONIC LIQUIDS; PHOTOELECTRON-SPECTROSCOPY; RADIOLYSIS
categoria
Chemistry; Science & Technology - Other Topics; Materials Science; Physics
autores
Strelcov, E; Arble, C; Guo, HX; Hoskins, BD; Yulaev, A; Vlassiouk, IV; Zhitenev, NB; Tselev, A; Kolmakov, A
nossos autores
Alexander Tselev
Investigador Principalagradecimentos
E.S. and H.G. 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. H.G. acknowledges support under the National Natural Science Foundation of China (Grant 11874105). A.Y. acknowledges support under the Professional Research Experience Program (PREP), administered through the Department of Chemistry and Biochemistry UMD. In part (A.T.), this work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/S0011/2020 and UIDP/50011/2020, financed by national funds through the FCT/MEC and, when appropriate, cofinanced by FEDER under the PT2020 Partnership Agreement. E.S. would like to thank Dr. Jabez McClelland for providing access to the AFM/SEM instrument, useful discussions, and a thorough reading of the manuscript.