Scientists from Brown University have come up with a new chemical catalyst to aid the generation of hydrogen fuel. A nanoparticle alloy of platinum and cobalt that is less expensive, more efficient and longer lasting than pure platinum catalysis. Hydrogen fuel is an emerging form of clean alternative to fossil-fuel that is relatively eco-friendly while still being capable of long distance travel that would otherwise be difficult for electric vehicles to sustain.
In a hydrogen fuel cell proton exchange membranes contain hydrogen on one side and air/oxygen on the other. By running a current through the cells cathode electrons are removed from the hydrogen atom and adopted by oxygen atoms “. This process of removal and re-attachment generates chemical energy that can then be harnessed by the fuel cell to power an engine.
However, in order to generate electricity a chemical catalyst is required to hasten the reaction. Platinum is the best catalyst for the job, unfortunately being a rare earth metal, it’s really expensive and prone to impurity. So scientists figured out that alloying platinum with cobalt is cheaper and more efficient, yet another problem arises. The base metal begins to oxidize inside of the fuel cell, leeching away.
In order to solve this problem they created nano-particles with an outer layer of pure platinum and interior composed of alternating layers of platinum and cobalt
“The layered arrangement of atoms in the core helps to smooth and tighten platinum lattice in the outer shell,” says says Shouheng Sun, professor of chemistry. “That increases the reactivity of the platinum and at the same time protects the cobalt atoms from being eaten away during a reaction. That’s why these particles perform so much better than alloy particles with random arrangements of metal atoms.”
The new nano-particle composite outperforms platinum, remaining active for 30 000 voltage cycles after which platinum declines significantly. Next they had to test the catalyst inside of an actual fuel cell, so they brought it to Los Alamos national lab where it surpassed milestones set by the US Department of Energy (DOE) for initial activity and long-term durability, with an initial activity of 0.56 amps per milligram and an activity after 30,000 cycles (roughly equivalent of five-years inside a fuel cell) of 0.45 amps.
“Even after 30,000 cycles, our catalyst still exceeded the DOE target for initial activity,” says Sun. “That kind of performance in a real-world fuel cell environment is really promising.”
The new catalyst marks a significant advancement in realizing hydrogen fuel powered cars, airplanes and even spacecraft. Asteroid mining for example plans to extract water ice from asteroids for use in hydrogen fuel cells. Once the ice is mined it can be melted and split in to oxygen and hydrogen to power satellites and perhaps even colonial ships.
Brown Universities platinum cobalt-catalyst is currently subject to provisional patent application which is the first step in commercialization.
Picture Credit: Sun lab/Brown University