To make a long story short, PEMFCs, or Proton Exchange Membrane Fuel Cells work this way: hydrogen is at first fed to the fuel cell’s input. There, hydrogen is split into a proton and an electron – this is the anode – the positive side of the fuel cell. The proton travels through the device and through a catalytic membrane, and the electron goes through an external circuit, creating a voltage between the poles, thus making something useful. At the negative side of the fuel cell, the protons, electrons and oxygen combine to form water, the fuel cell’s only waste product.
Well, everything looks nice and good until now, in theory. The problem with fuel cells are that the only stable and well-documented material that they make the catalyst from is platinum and platinum alloys. Other alloys have though recently been discovered, but the scientific community still insists on using platinum, because of its well-established presence in the fuel cell industry (even if it’s very expensive). Platinum resists the corrosive action of the fuel cell, and to make it efficient by increasing the usable surface, scientists make it from nanoparticles as small as two nanometers, which is in essence 10 platinum atoms across, hence very small.
Engineering assistant prof. Dane Morgan and Ph.D. student Edward (Ted) Holby, from the University of Wisconsin-Madison have discovered that making the fuel cells from platinum nanoparticles this small decreases the catalyst’s lifetime. Their explanation is simple:
“The stability of bulk versus nanoparticle materials can be understood intuitively by thinking of cheese,” says Morgan. “When you leave a large chunk of cheese out and the edges get crusty, the surface is destroyed, but you can cut that off and there is still a lot of cheese inside that is good. “But if you crumble the cheese into tiny pieces and leave it out, you destroy all of your cheese because a larger fraction of the cheese is at the surface.”
So, the researchers discovered that by making the particles 4 or 5 nanometers in size, they increase the catalyst’s lifetime dramatically, making platinum-based fuel cells cheaper, which is beneficial not only to the electric car industry, but also to the various applications that fuel cells have. Still, their research is only at its beginnings and should we see their discovery in action, we want to see it on cars first.
