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Controlling ion transport for a blue energy future

May 30, 2024
Osaka University
Researchers probed the transit of cations across a nanopore membrane for the generation of osmotic energy. The team controlled the passage of cations across the membrane using a voltage applied to a gate electrode. This control allowed the cation-selective transport to be tuned from essentially zero to complete cation selectivity. The findings are expected to support the application of blue energy solutions for sustainable energy alternatives worldwide.

Researchers from Osaka University show the control of ion passage through a nanopore membrane by applying a voltage to a gate electrode, paving the way for sustainable blue energy harvesting.

Blue energy has the potential to provide a sustainable alternative to fossil fuels. In simple terms, it involves harnessing the energy produced when the ions in a salt solution move from high to low concentrations. A team including researchers from Osaka University has probed the effect of voltage on the passage of ions through a nanopore membrane to demonstrate greater control of the process.

In a study recently published in ACS Nano the researchers looked at tailoring the flow of ions through the array of nanopores that make up their membrane, and how this control could make applying the technology on a large scale a reality.

If the membranes are made from a charged material, nanopores can cause a current to flow through them by attracting solution ions with the opposite charge. The ions with the same charge can then move through the pore generating the current. This means that the pore material is very important and choosing it has been the means of controlling the flow and current to date.

However, producing the exact same pore structures in a range of different materials to understand their comparative performances is challenging. The researchers therefore decided to investigate another way of tailoring the flow of ions across nanopore membranes.

"Instead of simply using the basic surface charge of our membrane to dictate the flow, we looked at what happens when voltages are applied," explains study lead author Makusu Tsutsui. "We used a gate electrode embedded across the membrane to control the field through voltage in a similar way to how semiconductor transistors work in conventional circuits."

The researchers found that with no voltage applied there was no charge generated by the flow of cations -- positively charged ions -- because they were attracted to the negatively charged membrane surface.

However, if different voltages were applied, this performance could be tuned to allow cations to flow, even providing complete selectivity for cations. This led to a six-fold increase in the osmotic energy efficiency.

"By enhancing the charge density at the surface of the nanopores that make up the membrane, we achieved a power density of 15 W/m2," says senior author Tomoji Kawai. "This is very encouraging in terms of progressing the technology."

The study findings reveal the potential for scaling nanopore membranes for everyday application. It is hoped that nanopore osmotic power generators will provide a means of bringing blue energy to the mainstream for a more sustainable energy future.

Story Source:

Materials provided by Osaka University. Note: Content may be edited for style and length.

Journal Reference:

  1. Makusu Tsutsui, Wei-Lun Hsu, Denis Garoli, Iat Wai Leong, Kazumichi Yokota, Hirofumi Daiguji, Tomoji Kawai. Gate-All-Around Nanopore Osmotic Power Generators. ACS Nano, 2024; DOI: 10.1021/acsnano.4c01989

Cite This Page:

Osaka University. "Controlling ion transport for a blue energy future." ScienceDaily. ScienceDaily, 30 May 2024. <>.
Osaka University. (2024, May 30). Controlling ion transport for a blue energy future. ScienceDaily. Retrieved June 19, 2024 from
Osaka University. "Controlling ion transport for a blue energy future." ScienceDaily. (accessed June 19, 2024).

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