M o d u L e 2 : a p p L i c a t I o n s a n d I m p L i c a t I o n s

nature of the catalyst and that of the 
electrolyte in the cell.
Currently, the electrodes in a fuel cell are made of a metal such as platinum (Pt), which is a rare, 
expensive metal, also sensitive to the CO and sulphur species that are dispersed in the atmosphere. 
These deactivate the platinum surface (a phenomenon called ‘poisoning of the catalyst’). Fuel cells 
operate at high temperatures (> 70 °C) since the poisoning agents at these temperatures tend to de-
adsorb. Nanotechnology is already actively involved in addressing some of the issues concerning fuel 
cell catalysts. Improvements in this area through nanotechnology concern (a) increasing the material 
catalytic activity; and (b) reducing the use of rare metals. Since the current generated at an electrode 
is proportional to the active surface of the catalyst, fuel cells that have higher power density can be 
formed from nanomaterials, which have a higher surface area to volume ratio. Electrocatalytic material 
properties are also proportional to particle size, so nanoparticles and nanomaterials have increased 
catalytic activity compared to bulk materials. This characteristic can lead to a reduction in the use of 
rare metals, for example by using carbon nanomaterials as a support for the dispersions of nano-sized 
platinum, thereby reducing the weight of platinum needed to produce the same surface area of active 
Pt catalyst. Carbon nanomaterials are particularly suitable since they act both as a support for the 
platinum nanomaterial and as a conductor. Suitable carbon nanomaterials are carbon foams containing 
nanopores, different types of nanotubes and single-walled nanohorns.
Proton exchange membrane fuel cell
The electrolyte conventionally used in fuel cells is aqueous KOH operating at about 70 °C (liquid alka-
line cell). It leads to corrosion of the electrodes, reducing the cell lifetime, and operates at high tem-
peratures, decreasing the thermodynamic efficiency of the cell. A solid electrolyte is preferred, there-
fore