Nature of the Electrical Double Layer on Suspended Graphene Electrodes.
Shanshan YangXiao ZhaoYi-Hsien LuEdward S BarnardPeidong YangArtem BaskinJohn W LawsonDavid PrendergastMiquel B SalmeronPublished in: Journal of the American Chemical Society (2022)
The structure of interfacial water near suspended graphene electrodes in contact with aqueous solutions of Na 2 SO 4 , NH 4 Cl, and (NH 4 ) 2 SO 4 has been studied using confocal Raman spectroscopy, sum frequency vibrational spectroscopy, and Kelvin probe force microscopy. SO 4 2- anions were found to preferentially accumulate near the interface at an open circuit potential (OCP), creating an electrical field that orients water molecules below the interface, as revealed by the increased intensity of the O-H stretching peak of H-bonded water. No such increase is observed with NH 4 Cl at the OCP. The intensity of the dangling O-H bond stretching peak however remains largely unchanged. The degree of orientation of the water molecules as well as the electrical double layer strength increased further when positive voltages are applied. Negative voltages on the other hand produced only small changes in the intensity of the H-bonded water peaks but affected the intensity and frequency of dangling O-H bond peaks. The TOC figure is an oversimplified representation of the system in this work.
Keyphrases
- raman spectroscopy
- room temperature
- high intensity
- single molecule
- high resolution
- carbon nanotubes
- ionic liquid
- molecular dynamics simulations
- risk assessment
- optical coherence tomography
- gold nanoparticles
- reduced graphene oxide
- density functional theory
- high speed
- climate change
- single cell
- transition metal
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