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Atomic-scale ion transistor with ultrahigh diffusivity

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Science  30 Apr 2021:
Vol. 372, Issue 6541, pp. 501-503
DOI: 10.1126/science.abb5144

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Gated ion flow in graphene oxide membranes

Cells are adept at fast, gated ion flow through tailored channels, which is key to many biological processes. Xue et al. developed ion transistors from reduced graphene oxide membranes and observed a field-enhanced diffusivity of the ions (see the Perspective by Hinds). By applying electrical gating, the average surface potential on the graphene layer could be controlled, thus altering the energy barrier for ion intercalation into the channel and leading to very high diffusion rates. The authors observed selective ion transport two orders of magnitude faster than the ion diffusion in bulk water.

Science, this issue p. 501; see also p. 459

Abstract

Biological ion channels rapidly and selectively gate ion transport through atomic-scale filters to maintain vital life functions. We report an atomic-scale ion transistor exhibiting ultrafast and highly selective ion transport controlled by electrical gating in graphene channels around 3 angstroms in height, made from a single flake of reduced graphene oxide. The ion diffusion coefficient reaches two orders of magnitude higher than the coefficient in bulk water. Atomic-scale ion transport shows a threshold behavior due to the critical energy barrier for hydrated ion insertion. Our in situ optical measurements suggest that ultrafast ion transport likely originates from highly dense packing of ions and their concerted movement inside the graphene channels.

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