Last updated February 8, 2018 at 10:37 am
By replacing platinum in fuel cells, hydrogen powered cars could become economically viable at last.
Hydrogen fuel cells promise energy without the pollution. They are the cleanest and the most promising power source for our future cars and electronics.
The problem is, they’re expensive.
A large portion of a fuel cell’s cost comes from the platinum catalyst used to split hydrogen and turn it into electricity.
Scientists have found a way around this prohibitive material cost by creating a catalyst made of porous carbon fibres and metal nanoparticles.
It is 100 times less expensive than platinum but just as effective.
‘A battery that runs on hydrogen’
“The key to the high performance of the materials we created is the combination of the chemistry and fibre processing conditions,” said lead researcher David Kisailus from the University of California, Riverside.
Fuel cells can be thought of as a battery that runs on hydrogen. Much like a battery, fuel cells are fabricated from a positive and negative electrode with an electrolyte in between.
When hydrogen is injected into the fuel cell, a catalyst helps separate the hydrogen molecules into positive and negative particles and we use the negative particles (electrons) to do our electrical dirty work.
The current favoured materials for catalysts in hydrogen fuel cells are either platinum or palladium. The metals attract the molecules and hold them in place so they have a greater chance of interacting in the right orientation for a reaction to occur. That speeds up the reaction which would otherwise be very slow. But both metals are so expensive that some experts are worried hydrogen cars are doomed before they have even got out of the gate.
Electrospinning, draws out nano fibres
This new research focused on replacing platinum with much cheaper metals and improving their catalytic ability with nanotechnology.
Scientists used a technique called electrospinning, where electric forces were used to draw out fibres of carbon with very small nanometre diameters.
The researchers embedded the fibres with metal nanoparticles made of cobalt, iron and nickel.
When they heated the fibres, they found that the material worked just as well as the platinum-based catalysts.
The excellent catalytic action was thought to arise from a combination of the metal nanoparticles and fabric-like network of fibres which both increased the surface area dramatically.
So the same principles that make a platinum catalyst so effective apply here. And the extra area offered as a result of the electrospinning make the cheaper metals as efficient.
Structural elements could also help power cars
“The remarkable electrochemical properties were primarily attributed to the synergistic effects obtained from the engineering of the metal oxide with exposed active sites and the 3D hierarchical porous graphitic structure,” said Kisailus.
Not only did the material perform exceptionally well regarding its catalytic performance, the researchers think that the carbon material’s lightweight and strong structure could mean that it could be used as structural components of a car.
“An important challenge in making high-performance vehicles is reducing weight, both from the body of the vehicle as well as extra weight from the battery or fuel cell, without affecting safety or performance,” said Kisalius.
“The material we created may enable automakers to turn structural components, such as the hood or the chassis, into functional elements that help power cars.”
The research was published in Small.