Researchers from Russia and Australia demonstrated that Nafion separator membrane partially releases some of its constituent fibers
Hydrogen fuel cells are an efficient source of continuous energy for remote applications. Nafion membrane is used to separate the anode and cathode within a fuel cell. However, fuel cell efficiency decreases as the size of Nafion increases when it interacts with water. Now, a team of researchers from Bauman Moscow State Technical University and Prokhorov General Physics Institute of the Russian Academy of Sciences found that Nafion separator membrane partially releases some of its constituent fibers that shuttle away from the surface into the bulk water phase.
The team examined a proposed hypothesis, which states that a new state of water leads to swelling of the Nafion membrane. The team described the growth of polymer fibers, which protrude from the membrane surface as it interacts with water. The increase in number of fibers was found to be directly proportional to deuterium concentration of the water. Nafion is the highest-performance commercially available hydrogen-oxide proton exchange membrane used in fuel cells. The membrane’s porous nature allows significant concentration of the electrolyte solution and separates the anode from the cathode. This in turn allows the flow of electrons to generate energy in the fuel cell.
The team found that the membrane is highly reactive to the deuterium content in the ambient water. The polymer fibers protrude from the membrane into the water. The effect is most significant in water with concentration of deuterium between 100 and 1,000 parts per million. To characterize the polymer fibers along the membrane-water interface, the team developed a specialized laser instrumentation called photoluminescent UV spectroscopy. Although the individual fibers were not visible directly due to the spatial limitation of photoluminescent UV spectroscopy, the team was successful in detecting their outgrowth into the water. The research was supported by grants from the Russian Federation for Basic Research, the President of the Russian Federation for Young Scientists, and the MEphI Academic Excellence Project and published in The Journal of Chemical Physics on October 23, 2018.