Longest Nanowires May Lead To Better Fuel Cells
We are searching for the alternative energy which can conveniently be used for our industrial and everyday purposes. Wind, water, geothermal and many other alternative energy sources are good and clean and green. But all of them lack one thing or another and don’t seem commercially viable. Researchers all over the world are trying to find solutions for this impending and inevitable energy crisis. Scientists from University of Rochester are trying to do the same thing. They are aiming to produce longest platinum nanowires. This feat has not been achieved by anyone. These longest platinum nanowires could make an impact on the development of fuel cells for cars, trucks and other devices. The wires, 1/50,000 the width of a human hair, are thousands of times longer than any previously made, according to a report in Nano Letters.
James C. M. Li who is the professor of mechanical engineering at the University of Rochester, states, “People have been working on developing fuel cells for decades. But the technology is still not being commercialized. Platinum is expensive, and the standard approach for using it in fuel cells is far from ideal. These nanowires are a key step toward better solutions.”
These platinum nanowires are better for the longevity and efficiency of fuel cells. Till now these nanowires are utilized in the spacecrafts only. Now team of researchers at University of Rochester are of the view that platinum nanowires can be exploited as modes of transport fuel. “Our ultimate purpose is to make free-standing fuel cell catalysts from these nanowires,” says Li. This discovery would reduce the consumption of conventional fuels.
Fuel cells require catalysts that can facilitate the reaction of hydrogen and oxygen. This will split the compressed hydrogen fuel into acidic hydrogen ion and release the electrons. These electrons are diverted into an external circuit to provide energy. What happened to the hydrogen ions? Those hydrogen ions combine with electrons and oxygen to create the byproduct in the form of liquid or vaporous water.
Platinum has been the chief substance utilized as catalysts in making fuel cell because platinum has the ability to endure the harsh acidic environment inside the fuel cell. Platinum’s energy efficiency is also considerably greater than that of cheaper metals like nickel.
The efficiency of the catalysts in increased by maximizing the exposed surface area of platinum nanoparticles. The technology has already been used or nanocomputers and other nano devices. The big difference in the platinum nanowires produced by Li and his graduate student Jianglan Shui is that by a process known as electrospinning they have produced platinum nanowires that are thousands of times longer than any previous such wires.
Making such nanowires is a highly challenging task. “The reason people have not come to nanowires before is that it’s very hard to make them,” says Li. “The parameters affecting the morphology of the wires are complex. And when they are not sufficiently long, they behave the same as nanoparticles.”
The problem with previous technologies is that they heavily depend on nanoparticles in order to expose the surface area of platinum to the maximum. The more surface area there is, apparently the greater is the efficiency. But the basic problem is these particles can always merge through a process called surface diffusion, combining, and consequently reducing the total surface area and the amount of energy produced. The second problem is that nanoparticles need the carbon support structure to stop them from going haywire. Carbon is subject to oxidation, and these particles don’t go well with carbon structures. As the carbon degrades, the particles are permanently lost.
This doesn’t happen in the case of nanowires. Since platinum is uniformly arranged in a thin wire the particles comprising them do not need the carbon structures to support them.
Beads that would have formed on the platinum nanowires would have caused another problem and Li’s team has taken care of it. “With platinum being so costly, it’s quite important that none of it goes to waste when making a fuel cell,” says Li. “We studied five variables that affect bead formation and we finally got it—nanowires that are almost bead free.”