A team from Monash University in Australia has developed an ultrathin membrane able to operate hydrogen fuel cells at 250 °C and, most surprisingly, without the need for water. This is a wall in which technology has been crossing for a long time and the discovery has been published in the journal Science Advances. Below these lines we tell you all the details.
Why is it important. Hydrogen cells are one of the great promises to decarbonize transportation, heavy industry and sectors where batteries fall short. They only emit water and heat, they recharge quickly and offer autonomy comparable to gasoline.
The problem is that current membranes, such as those based on Nafion (a synthetic resin), they need to be permanently hydrated so that the protons can circulate. And that forces us to operate below 80-100 °C, because at higher temperatures the water evaporates and the entire system collapses.
In detail. The team, led by researchers Huanting Wang and Kaiqiang He, has built atomic-thick nanosheets made of graphene and boron nitride. Between those layers they have introduced phosphoric acid in a state that researchers call nanoconfined, where the acid is trapped in tiny spaces from which it cannot escape or evaporate, even at 250 ° C.
The result It is a membrane of just 50 micrometers, named GBP, that acts as a dry highway through which protons move at high speed without depending on a single drop of water.
How it works. Wang, professor in the Department of Chemical and Biological Engineering at Monash, account that “by combining proton-conducting nanosheets with nanoconfined phosphoric acid, we have developed a membrane that maintains rapid proton transport without water.” The trick is in a mechanism that the authors define as synergistic, in which protons directly pass through the hexagonal rings of graphene and boron nitride and, at the same time, jump along the network of hydrogen bonds that forms the acid confined between layers.
On the other hand, He adds that this combination is what gives the membrane high conductivity and stability in dry and high temperature conditions.
The figures. In laboratory tests GBP achieved a proton conductivity of 166 mS cm⁻¹ at 250 °C and a power density of 1,011 mW cm⁻² in a hydrogen-oxygen stack, well above industry reference membranes. In addition, the team kept it running for 150 hours straight at that temperature without signs of degradation.
Between the lines. Working at 250°C is a game-changer on several fronts.
- One: The water management and humidification systems are eliminated, which in current hydrogen cars are heavy, bulky and expensive.
- Two: at that temperature the platinum catalyst tolerates impurities better such as carbon monoxide, which opens the door to using less pure hydrogen and, therefore, cheaper to produce.
- Three– Cooling the system becomes much easier, allowing for smaller radiators and lighter vehicles.
Beyond the car. Although we usually focus on the hydrogen cars When we talk about this type of technology, the truth is that the potential applications go much further. GBP was also tested in direct methanol cells and performed at 502 mW cm⁻² with 16 M concentrated methanol at 250 °C. This suggests that it could be used for portable systems where hydrogen is difficult to store.
In addition, the authors point to uses in data centersplanes, trains, factories and hospitals as energy backup, and other electrochemical processes such as the separation of water molecules, the reduction of carbon dioxide or the synthesis of ammonia.
And now what. The next step is the usual one. And when a laboratory announces an advance like this, we have to wait until it ends up coming to fruition and its commercialization on an industrial scale is viable. If they succeed, the combination of cheaper batteries, less pure hydrogen and simpler systems could accelerate the arrival of this technology in sectors where electrification with batteries does not quite fit.
Cover image | CARMAN and Monash University
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