Carbon nanotubes may lower cost of fuel cells.(CARBON NANOTUBES)

The high cost of manufacturing fuel cells makes their large-scale production for power generation next to impossible, but researchers at Arizona State University are now studying proton exchange membrane fuel cells (PEMFC), which employ carbon nanotube-based catalysts and electrodes, so that cars, electricity and much more can run on the environmentally friendly technology.

Fuels cells cleanly and quietly generate electric power by passing fuels like hydrogen over one electrode while passing air over a second electrode. However, fuel cell development has been dogged by costs of the technology, due to its need for platinum-based catalysts, as well as safety concerns, says Engineering Technology Professor, Arunachalanadar Madakannan (Kannan), who has been studying PEMFCs for more than eight years and led the project.

"Platinum is the most effective electro-catalyst and a good conductor of electricity in fuel cells, but the cost is so prohibitive that we have not yet been able to use fuel cells widely", says Kannan.

PEMFC fuel cells have layers of electrode and electrolyte components. The cell in a PEMFC is made up of a hydrogen-based positive (anode) terminal and oxygen-based negative (cathode) terminal, with carbon-particle supported platinum acting as a catalyst (electrode) to produce power. While fuel cells produce electrical energy, the only waste generated is water, so it is considered a clean energy conversion system.

Kannan is working to create lower cost PEMFCs by directly growing carbon nanotubes on carbon paper substrates, otherwise known as the gas diffusion layer, rather than spherical carbon-particles, and then deposit platinum nanoparticles onto the surface of the nanotubes. This innovative approach allows for the use of less platinum without impacting energy efficiency.

"This modified process saves about 10-15% of the cost compared with what exists today, without sacrificing any power output", notes Kannan.

During his research, Kannan was evaluating the performance of several different materials, measuring power output and efficiency along the way.

"The carbon nanotube-based electrode is more efficient because it has a greater surface area, which means less platinum is needed. In addition, the electrodes perform extremely well under lower relative humidity, which will ultimately reduce the fuel cell system complexity."

The researchers say that the next step will be to make the development of the gas diffusion layer continuous, rather than a batch process, so that it can be commercially viable. They also believe that PEM fuel cells will become commercially viable in a decade or so, which will promote a movement towards a hydrogen-based economy.

For further information, contact: Arunachalanadar Madakannan, Engineering Technology Professor, Department of Electronic Systems, Arizona State University at the Polytechnic campus, 7001 E Williams Field Road, Tech 156, Mesa, AZ 85212, USA; tel: 480-727-1102; E-mail: amkannan@asu.edu; http://www.asu.edu

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