A team led by Dr. Zoe Schnepp at the University of Birmingham recently cooked up a recipe for a new catalyst that can be used in fuel cells. The process calls for three major ingredients: magnesium, iron, and gelatinthe protein that is used to make jelly desserts.
How Do Fuel Cells Work?
All fuel cells consist of three basic parts: an anode, a cathode, and an electrolyte. Hydrogen flows in at the anode of the fuel cell, where a catalyst breaks down the hydrogen into electrons and ions. The electrons created by the anode then travel through a wire and create electricity. Next, the ions exit through the electrolyte to the cathode, where they react with a third chemical (usually oxygen) to create the FCEV’s primary emission: water.
To recap: hydrogen and oxygen flow into the fuel cell, electricity is generated, and the only emissions are heat and water.
FCEVs can help to reduce greenhouse gas (GHG) emissions and to improve the nation’s air quality, but they pose a unique challenge to automakers: they are often costly to produce, largely because they use platinum as a catalyst. In fact, the platinum in a fuel cell typically contributes to about 40% of the total unit cost, according to Nanowerk.
Shown above is a cross section of a polymer electrolyte (PEM) fuel cell. Note that hydrogen flows in at the anode side of the fuel cell, and oxygen at the cathode side, in order to produce energy, heat, and water. Credit: NAFTC.
Gelatin, Magnesium and Iron as a Catalyst
The study led by Dr. Zoe Schnepp offers an alternative to platinum as a catalyst, which means that fuel cells could become increasingly cheaper to produce.
Instead of using platinum as a catalyst, Dr. Zoe Schnepp and her team developed an alternative option that used magnesium, iron, and gelatin.
Dr. Schnepp explained the process in an interview with Nanowerk. “We mix gelatin with iron and magnesium nitrates in water. The precursor is therefore a homogeneous solution. As the material dries, it spontaneously foams.”
After the material foams, it creates its own “intricate sponge-like structure,” according to the chemistry professor.
Next, the mixture is heated to 800 degrees Celsius, and nanoparticles of a compound called iron carbide form inside the sponge. These nanoparticles are eventually dissolved, leaving tiny holes in the walls of the sponge-like structure. The result is a structure that is high in surface area.
Having a high surface area is an important advantage in a fuel cell catalyst, since it allows the gaseous reactants to flow through it more efficiently.
The result is that the new catalyst that Dr. Zoe Schnepp and her team developed is nearly as efficient as a platinum catalyst in a fuel cell, and much less expensive to produce.
“One of the biggest challenges for materials science is to design sustainable materials. This includes materials made from cheap and abundant resources and also simple and safe manufacturing methods,” said Dr. Zoe Schnepp. “Unlike platinum, which is rare, our new material is made up of the abundant and cheap elements iron and magnesium. By combining these with gelatin, we have made an effective material which shows remarkable performance in generating electricity comparable to a commercial platinum catalyst. The key is that the gelatin material is not only cheap, but it’s extremely easy to make.”
The study was published on October 1 in the Journal of Materials Chemistry A, a weekly journal that covers all aspects of materials chemistry related to energy and sustainability. For an abstract of the paper, “Doped-carbon electrocatalysts with trimodal porosity from a homogeneous polypeptide gel,” please click here.