Published February 4, 2022 | Version Published
Journal article Open

Ion-transfer electrochemistry at arrays of nanoscale interfaces between two immiscible electrolyte solutions arranged in hexagonal format

  • 1. College of Science and Engineering, James Cook University, Townsville, Queensland, 4811 Australia
  • 2. Memorial University of Newfoundland, Department of Chemistry, 283 Prince Philip Dr., St. John's, Newfoundland, Canada A1B 3X7
  • 3. John de Laeter Centre, Curtin University, GPO Box U1987, Perth, Western Australia, 6845 Australia
  • 4. The Bernal Institute and Department of Chemical Sciences, School of Natural Sciences, University of Limerick (UL), Limerick V94 T9PX, Ireland.
  • 5. School of Molecular and Life Sciences, Curtin University, GPO Box U1987, Perth, Western Australia, 6845 Australia

Description

The electrochemical behaviour of hexagonally arranged nanopore arrays was studied by simple ion transfer across the interface between two immiscible electrolyte solutions (ITIES) formed between water|1,2-dichloroethane. The hexagonal nanoITIES arrays were supported at nanopores fabricated by focused ion beam milling into 50 nm thick silicon nitride films. Six arrays with different pore centre-to-centre distance (rc) to radius (ra) ratios were prepared. Within these arrays, the diffusion-limited steady-state currents (iss) of tetrapropylammonium cation (TPrA+) ion transfer increased concomitantly with increasing rc/ra ratio, reaching a plateau at rc/ra ≥ 96, which is greater than that previously reported for square-patterned nanoITIES arrays (rc/ra ≥ 56). The diffusion regime and iss associated with simple ion transfer across a nanopore array was also examined using numerical simulations, via COMSOL Multiphysics software, incorporating a 3-dimensional geometry and employing finite element analysis. Simulated linear sweep voltammograms of TPrA+ transfer demonstrated a unique diffusional behaviour dependent on hexagonal nanopore spacing and the rc/ra ratio, analogous to the experimental voltammograms. Overlay of simulated and experimental voltammograms for each rc/ra ratios showed good agreement. These results indicate that a new design criterion is required to achieve independent diffusion at hexagonal nanointerface arrays, in order to maximize nanodevice performance in electrochemical sensor technologies.

Notes

This work was supported by the Australian Research Council (DP130102040), the Natural Science and Engineering Research Council of Canada (Discovery Grant #006074-2019), Memorial University of Newfoundland, and James Cook University. The authors acknowledge the use of equipment, scientific and technical assistance of the John de Laeter Centre, Curtin University, which has been partially funded by the University and by the State and Commonwealth Governments.

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Additional details

Funding

Designing Reactive Functionalised Soft Interfaces _ Self-healing soft materials for solar energy conversion, energy storage, and sustainable low cost hydrogen production 13/SIRG/2137
Science Foundation Ireland
SOFT-PHOTOCONVERSION – Solar Energy Conversion without Solid State Architectures: Pushing the Boundaries of Photoconversion Efficiencies at Self-healing Photosensitiser Functionalised Soft Interfaces 716792
European Commission