A Silver Lining in the Hunt for Green Energy: Making Hydrogen Production Easier

Scientists develop a modified proton exchange membrane that improves the production of highly pure hydrogen

Microbial electrolysis cells are devices used to produce high-purity hydrogen from organic matter. Inside these cells, exchange of charged particles occurs via a polymeric membrane. However, “biological fouling” or the accumulation of organic matter on the membrane surface limit the efficiency of these cells. Recently, scientists of the Republic of Korea found a way to overcome this, by developing a high-performance membrane resistant to biofouling.

As the world is on the brink of exhausting its fossil fuel resources, researchers globally are investing tremendous efforts to look for effective “clean” sources of energy. One viable option is hydrogen (H₂), a practical, highly efficient fuel that can be produced from biomass-based substrates like wastewater. One way to generate H₂ is using microbial electrolysis cells (MECs), in which electrochemically active microorganisms catalyze the oxidation of organic compounds to produce H₂. As part of this process, charged particles called “protons” and “electrons” react with each other in the cathode chamber of an MEC, generating highly purified H₂. A proton exchange membrane (PEM) facilitating the proton-electron reaction is, thus, a central player in the functioning of the cell. But often, the proton transportation ability of PEMs is impeded due to the accumulation of organic matter on its surface―a process called “biofouling.” This, unfortunately, limits the efficiency and longevity of MECs. Therefore, to leverage the full potential of MECs, it is crucial to use find ways to mitigate biofouling-related blockage in PEMs.

To achieve this goal, a team of scientists at National Korea Maritime & Ocean University, led by Dr Kyu-Jung Chae, set out to design an anti-biofouling PEM (and a 2D nanomaterial-based PEM). Their findings are published in International Journal of Hydrogen Energy. Dr Chae says explains their aim, “A paradigm shift in the field of energy production and consumption will take us closer to sustainable energy generation, and H₂ is an attractive candidate in this regard. If high-performance 2D nanomaterial-based membranes with robust anti-biofouling properties are commercialized, H₂ production can become easier and more cost-effective.”

To develop such a membrane, the scientists focused on silver nanoparticles (AgNP), which are known for their anti-fouling properties. But, using AgNP renders the membrane a hydrophobic nature. Moreover, immobilizing AgNP onto the membrane is a complex process. To overcome these challenges, the scientists decided to use another coating agent, with anti-biofouling and hydrophilic properties, to make AgNP immobilization easier. A compound called “polydopamine” (PDA) fitted the bill perfectly, and thus a PEM using PDA and AgNPs was designed.

When the scientists tested the modified membrane, it showed significantly higher anti-biofouling property than the non-modified ones or those single-coated with either AgNP or PDA. They also observed that best result was obtained when PDA was applied before AgNP coating. Moreover, when equipped with this 2D nanomaterial-based PEM, the MEC showed high H₂ recovery performance, even after 6 months of operation. Prof Chae and his team have further elaborated the potential applications of 2D material-based membranes for H₂ purification in another study published in the same journal.

Discussing the impact of their study, Dr Chae seems enthusiastic, “By leveraging the durability of the high-performance membranes that adopt different nanomaterial-based augmentation, it is possible to develop highly efficient MECs producing H₂ from biomass. Commercializing such cost-effective MECs will help to realize the global dream of a society that thrives on sustainability.”

This study is, indeed, a big win for the environment―taking us closer to a sustainable future.

DOI: https://doi.org/10.1016/j.ijhydene.2020.04.059

*Corresponding author’s email: ckjdream@kmou.ac.kr

About the author

Dr Kyu-Jung Chae is an Associate Professor of Environmental Engineering at Korea Maritime and Ocean University (KMOU). Before joining KMOU, he completed his PhD in environmental engineering from Gwangju Institute of Science and Technology (GIST), South Korea. He has spent over 19 years working in both academia and the industry. His understanding of the real needs in both fundamental and practical environmental research stems from his balanced experience.