University of Manchester (UM) researchers have found that a graphene membrane, which is impermeable to all gases and liquids, can easily allow protons to pass through it.

The discovery could revolutionize fuel cells and other hydrogen-based technologies because they require a barrier that only allow protons – hydrogen atoms stripped off their electrons – to pass through.

Protons Passing Through a Membrane in an Artists Rendering.  Image Credit: The University of Manchester.  Click image for the largest view.

Protons Passing Through a Membrane in an Artists Rendering. Image Credit: The University of Manchester. Click image for the largest view.

In something of a reach they team notes graphene membranes could be used to sieve hydrogen gas out of the atmosphere, where it is present in minute quantities, creating the possibility of electric generators fueled by an atmosphere component that would otherwise most likely fly off into space.

The team’s paper has been published in the journal Nature.

On background, the one atom thick graphene material, renown for its barrier properties, has a number of uses in applications such as corrosion-proof coatings and impermeable packaging, was first isolated and explored in 2004 by a team at UM.

The graphene membrane is good stuff. For example, it been suggested that it takes the lifetime of the universe for hydrogen, the smallest of all atoms, to pierce a graphene monolayer. We’ll see someday.

But for now a group led by Sir Andre Geim tested whether protons are also repelled by graphene. The team fully expected that protons would be blocked, as existing theory predicted as little proton permeation as it would be for hydrogen.

Its a good thing they team checked. In spite of the pessimistic prognosis, the researchers found that protons pass through the ultra-thin crystals surprisingly easily, especially at elevated temperatures and if the films were covered with catalytic nanoparticles such as platinum.

The discovery makes monolayers of graphene, and its sister material boron nitride, attractive for possible uses as proton-conducting membranes, which are at the heart of modern fuel cell technology.

Fuel cells use oxygen and hydrogen as a fuel and convert the input chemical energy directly into electricity. Without membranes that allow an exclusive flow of protons but prevent other species to pass through, this technology would not exist.

Despite being well-established, fuel-cell technology requires much more improvement in upfront coast and replacement to make it more widely used. One of the major problems is a fuel crossover through the existing proton membranes, which reduces their efficiency and durability.

The UM research suggests that the use of graphene or monolayer boron nitride can allow the existing membranes to become thinner and more efficient, with less fuel crossover and poisoning. This can boost competitiveness of fuel cells.

The UM team also demonstrated that their one atom thick membranes can be used to extract hydrogen from a humid atmosphere. They hypothesize that such harvesting can be combined together with fuel cells to create a mobile electric generator that is fuelled simply by the hydrogen present in air.

Marcelo Lozada-Hidalgo, a PhD student and corresponding author of this paper, said: “When you know how it should work, it is a very simple setup. You put a hydrogen-containing gas on one side, apply small electric current and collect pure hydrogen on the other side. This hydrogen can then be burned in a fuel cell. We worked with small membranes, and the achieved flow of hydrogen is of course tiny so far. But this is the initial stage of discovery, and the paper is to make experts aware of the existing prospects. To build up and test hydrogen harvesters will require much further effort.”

Dr Sheng Hu, a postdoctoral researcher and the first author in this work, added: “It looks extremely simple and equally promising. Because graphene can be produced these days in square meter sheets, we hope that it will find its way to commercial fuel cells sooner rather than later.”

Its pretty impressive news right of the start. The paper abstract includes study of hexagonal boron nitride that passes the protons quite well at room temperature. As temperatures climb the graphene monolayer takes over the lead. Both benefit from catalysts added to there surfaces.

That leaves the question of all the possible catalysts. Some folks are gong to be really busy because this technology offers a lot of potential.


1 Comment so far

  1. Kunkiw Lee on May 9, 2017 3:00 PM

    I am glad much. I will learn more by your kindness. Thank you.

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