Shape matters: Enhanced osmotic energy harvesting in bullet-shaped nanochannels

• Published in: Nano energy Vol. 71; p. 104612
• Main Authors: Laucirica, Gregorio, Albesa, Alberto G., Toimil-Molares, María Eugenia, Trautmann, Christina, Marmisollé, Waldemar A., Azzaroni, Omar
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2020
• Subjects: Blue energy; Concentration polarization; Ion transport; Nanofluidics; Osmotic power generation; Ion transport; Nanofluidics; Blue energy; Concentration polarization; Osmotic power generation
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2020.104612

Nanofluidic reverse electrodialysis systems based on track-etched nanochannels are promising devices for new eco-friendly ways of sustainable energy generation. In recent years, several works have been focused on the influence of parameters such as pH, ionic strength, and chemical nature of the electrolyte on the device performance. However, despite the relevance of the geometry on the channel properties, the influence of the nanochannel shape on the performance of energy conversion remains almost unexplored. In this work, we present an experimental study – complemented with Poisson–Nernst–Planck simulations – that describes how the shape of the nanochannels strongly affects the energy conversion performance of single bullet-shaped nanochannels created on PET foils by the ion-track-etching method. To test optimal parameters for energy conversion and selectivity, the performance was investigated by varying the channel effective diameter as well as the pH and the electrolyte gradient. With a maximum output power of 80 pW, this system reveals the best value reported for a bare single track-etched nanochannel. Therefore, this work experimentally demonstrates that it is possible to obtain high power output by means of a careful choice of channel geometry and etching conditions, in addition to other experimental parameters such as pH and electrolyte gradient. We believe that these results offer a promising framework to explore new design concepts in nanofluidic osmotic power generators. [Display omitted] •Shape strongly affects the energy conversion performance of single nanochannels created by the ion-track-etching method.•Bullet-shaped nanochannels reach a maximum output power of 80 pW, the best value reported for bare track-etched nanochannels.•The power obtained in bullet-shaped nanochannels exceeds several values reported previously for other materials.•PNP simulations indicate that the superior performance of bullet-shaped nanochannels relies on the larger channel volumes.