A research team led by Kim Seong-jae, a professor in the Department of Electrical and Computer Engineering at Seoul National University's College of Engineering, said on the 5th it has developed a new energy-recovery purification system that can produce purified water and hydrogen at the same time.
Securing clean water and clean energy at the same time is among the most important challenges humanity faces today. Yet purifying water requires electricity, and producing electricity again requires water, creating a paradox. As a result, the need is growing for technology that can solve both problems together.
The team developed a platform that simultaneously produces purified water and hydrogen by leveraging ion concentration polarization. Ion concentration polarization occurs when an electric field is applied across an ion-selective membrane, causing ions to separate to either side of the membrane, making one side more concentrated and the other more dilute.
The purification technology developed can produce purified water and hydrogen energy at the same time. As current is passed through a specialized membrane, salts and contaminants are removed on one side of the membrane to create clean water, while on the other side hydrogen ions receive electrons at the electrode and are reduced to hydrogen gas. In other words, a single electrochemical reaction simultaneously produces purified water and hydrogen.
To experimentally verify this principle, the researchers first fabricated a microfluidic device, then used fluorescence imaging to simultaneously observe the purified-water region (ion depletion region) and hydrogen bubble generation. They then achieved hydrogen production of several milliliters (mL) per hour and stable production of purified water in a finger-sized device made with a 3D printer.
As a result, about 10% of the electrical energy used for purification was recovered as hydrogen energy, and the team confirmed a tendency for hydrogen production to increase linearly as current increased. The system also showed stable generation of purified water even in highly concentrated brine, demonstrating the potential to apply the technology to seawater or saline water.
The system operates with a single-membrane structure and works without a separate high-pressure pump. Thanks to this, the device is simple and lightweight, allowing it to be scaled as a portable or distributed purification unit. And because it was developed as a compact, modular device, it can be expanded into a variety of large units through module assembly. It can be applied across a range of scales, from small personal purifiers to mobile units for disaster response, and can be used effectively in places with limited infrastructure, such as military operational areas or space exploration environments.
Kim said, "The key to this research is that it shows the possibility of moving beyond the conventional approach of handling water and energy separately to solve both simultaneously in a single system," adding, "We plan to miniaturize and modularize this technology so it can evolve into a platform that allows anyone to easily secure water and energy even in extreme environments such as disaster sites or spacecraft."
The results of this research were recently published online in the international materials science journal "Communication Materials."
References
Communication Materials (2025), DOI: https://doi.org/10.1038/s43246-025-01001-z