Gated proton transport in aligned mesoporous silica films

Abstract

Modulated proton transport plays significant roles in biological processes such as ATP synthesis as well as in technologically important applications including, for example, hydrogen fuel cells. The state-of-the-art proton-exchange membrane is the sulphonated tetrafluoroethylene copolymer Nafion developed by DuPont in the late 1960s, with a high proton conductivity. However, actively switchable proton conduction, a functional mimic of the ion transport within a cell membrane, has yet to be realized. Herein, we report the electrostatic gating of proton transport within aligned mesoporous silica thin film. It is observed that surface-charge-mediated transport is dominant at low proton concentrations. We have further demonstrated that the proton conduction can be actively modulated by two-fourfold with a gate voltage as low as 1 V. Such artificial gatable ion transport media could have potential applications in nanofluidic chemical processors, biomolecular separation and electrochemical energy conversion.

Robust Sandwich‐Structured Nanofluidic Diodes Modulating Ionic Transport for an Enhanced Electrochromic Performance

“…The dashed line represents the ionic conductance of the bulk solution, which is proportional to the electrolyte concentration. However, the transmembrane ionic conductance apparently deviates from the bulk value at below 0.5 m , indicating a surface‐charge dominant ionic transport was applicable to our sandwich‐structured nanofluidic diodes with charged exterior surfaces 14. Therefore, the ion rectification behavior could be achieved even in electrolytes of high concentration close to 1 m .…”

Protonic transistors from thin reflectin films

“…21 Although this ratio was certainly below values of >10 6 reported for organic transistors, 25 it compared favorably to the best values found for protonic transistors under comparable conditions and in analogous configurations (Table I). 12,13,21 These observations underscored the excellent performance of the thin reflectin film-based protonic transistors.…”

“…Within the broader ionic transistor class of devices, there have been several reports of protonic transistors, [10][11][12][13][14][15][16] including two notable examples from the Rolandi group. 13,14 For these devices, the application of a voltage to the gate modulates the current flow between the source and the drain, in analogy to conventional unipolar field effect transistors.…”

Self-assembled two-dimensional nanofluidic proton channels with high thermal stability

“…For comparison, the mobility of vermiculite is comparable to what has been seen in the commercial proton conductor Nafion 34,37 . Alternatively, as shown in literature 16 , surface charge density could also be estimated from the graph of concentration versus conductivity (for example, Fig. 3d) based on a set of simplified hypotheses ( Supplementary Fig.…”

“…This lengthscale is similar to the size of solvated ions as well as the Debye length of electrolytes at up to physiological concentrations. Many works have used similarly sized nanofluidic channels, fabricated by lithography or using a sacrificial template, to demonstrate that ions behave very differently in confined environments than they do in bulk [13][14][15][16][17] . For example, when the channel dimension becomes comparable to Debye length, ions carrying the opposite charge to the channel wall become enriched, and ions carrying the same charge as the channel wall are excluded.…”