Surface images of nanoparticles could advance energy systems

October 04 2008 / by Garry Golden
Category: Energy   Year: 2013   Rating: 2

Trying to make the case that surface area is important to the future of energy is difficult. Surface area is not a sexy concept, and nearly impossible to fit into a media sound clip.

Barack Obama and John McCain do not call for energy systems with high surface area nano-catalysts. Instead they call for cheaper solar, and more powerful batteries and fuel cells for electric vehicles. Energy researchers would say – same thing!

Saying nanoparticles is a little better and certainly ripe for a media sound bite. But what if you could take a picture of molecules on a nanoparticle surface?

Now a group of researchers led by MIT have released the first composite atomic-scale images of the catalytic surface area of platinum-cobalt nanoparticles used in fuel cells. Their efforts could accelerate the development of electric fuel cell vehicles.

Surface area and the future of energy
Energy reactions occur when molecules interact. We simply capture the released energy. The cost and performance of batteries, fuel cells and capacitors depends on how molecules react (or do not interact) on tiny pieces of elements like lithium, carbon, titanium, and platinum.

The smaller the pieces, the more surface area, the more molecule interactions, the better the reaction. It also means lower cost because you use less material(e.g. expensive platinum).

If we can see the surface area of nanoscale designed catalysts we can design better (and cheaper) catalysts used in fuel cells.

First images of nanoparticle platinum-cobalt surface
Today a group of researchers from MIT, UT-Austin and ORNL has released images of nanoscale surface by using a technique known as Scanning Transmission Electron Microscopy.

The researchers analyzed platinum and cobalt nanoparticles to understand why the performance of a combined catalyst was more reactive than simply using platinum alone.

Now the researchers can propose and test theories to why the material is so reactive. If researchers can design catalysts with less platinum, the cost of fuel cells could drop dramatically.

The same principle of surface area applies to building better batteries and capacitors. If we can apply this imaging technique across all devices, we could accelerate commercialization of highly efficient energy storage systems.

Surface area notes for:

Batteries – surface area is important for developing better performing and safer lithium ion batteries. Altair Nanotechnologies has developed a lithium ion battery using nanoscale applications of titanium dioxide particles.

Capacitors and ultra capacitors store electricity in the form of a physical charge. Their energy density and performance is proportional to the surface area of the electrodes.

Fuel cells offer a unique blend of high efficiency and control over electrochemical reactions of gas to electricity conversion. Increasing catalytic surface area improves performance and lowers cost. Put simply, the more fuel (e.g. methanol or hydrogen) that comes in contact with the catalyst, the more electricity from the device.

It is unlikely that surface area will emerge as an energy buzzword. But few things are as concrete in terms of leveraging real change in advanced energy devices.

In all three devices, nanostructured surface areas and catalyst design allow us to compress more power into smaller volumes. Seeing what that surface looks like in real life is important. And we hope the MIT, UT-Austin and ORNL teams get their applause.

Image courtesy / Electrochemical Energy Laboratory at MIT

Left image highlights two platinum-cobalt catalyst nanoparticles (inside the dashed boxes) with a ‘sandwich’ structure of platinum and cobalt atoms near the surface. At right is a cross-sectional model corresponding to the lower particle, showing platinum atoms enriched in the outermost layer, cobalt enriched in the second, and additional layers containing a mixture of the two.

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